diff --git a/.travis.yml b/.travis.yml
index 1d9e00f..1680e7d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,16 +1,19 @@
 language: php
 php:
   - 5.6
-  - 5.3
 
 services:
   - redis-server
 
 before_script:
+  - echo yes | pecl install apcu-4.0.11
+  - echo "apc.enabled = 1" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
+  - echo "apc.enable_cli = 1" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - echo "extension = redis.so" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
   - composer self-update
   - composer install --no-interaction --prefer-source --dev
   - phpenv rehash
+  - php -i
 
 script:
   - vendor/bin/phpunit --verbose --colors
diff --git a/README.md b/README.md
index 53e9bff..d5e1ff0 100644
--- a/README.md
+++ b/README.md
@@ -4,20 +4,15 @@
 [![Code Climate](https://codeclimate.com/github/Jimdo/prometheus_client_php.png)](https://codeclimate.com/github/Jimdo/prometheus_client_php)
 
 
-This library uses Redis to do the client side aggregation.
-We recommend to run a local Redis instance next to your PHP workers.
+This library uses Redis or APCu to do the client side aggregation.
+If using Redis, we recommend to run a local Redis instance next to your PHP workers.
 
-## Why Redis?
+## How does it work?
 
 Usually PHP worker processes don't share any state.
-
-We decided to use Redis because:
- * It is easy to deploy as a sidecar to the PHP worker processes (see [docker-compose.yml](docker-compose.yml)).
- * It provides us with easy to use concurrency mechanisms we need for the metric aggregation (e.g. `incrByFloat`).
-
-We think this could be implemented with APCu as well and we might do so in the future.
-Of course we would also appreciate a pull-request.
-
+You can pick from two adapters.
+One uses Redis the other APC.
+While the former needs a separate binary running, the latter just needs the [APC](https://pecl.php.net/package/APCU) extension to be installed.
 
 ## Usage
 
@@ -73,8 +68,9 @@ Also look at the [examples](examples).
 
 ### Dependencies
 
-* PHP 5.3/5.6 (at least these versions are tested at the moment)
+* PHP 5.6
 * PHP Redis extension
+* PHP APCu extension
 * [Composer](https://getcomposer.org/doc/00-intro.md#installation-linux-unix-osx)
 * Redis
 
@@ -98,5 +94,10 @@ Just start the nginx, fpm & Redis setup with docker-compose:
 ```
 composer require guzzlehttp/guzzle=~6.0
 docker-compose up
-vendor/bin/phpunit tests/Test/BlackBoxTest.php
+```
+Pick the adapter you want to test.
+
+```
+ADAPTER=redis vendor/bin/phpunit tests/Test/BlackBoxTest.php
+ADAPTER=apc vendor/bin/phpunit tests/Test/BlackBoxTest.php
 ```
diff --git a/composer.json b/composer.json
index 27f2a60..121d587 100644
--- a/composer.json
+++ b/composer.json
@@ -4,17 +4,22 @@
         {
             "name": "Joscha",
             "email": "joscha@schnipseljagd.org"
+        },
+        {
+            "name": "Jan Brauer",
+            "email": "jan.brauer@jimdo.com"
         }
     ],
     "require": {
-        "php": ">=5.3.3",
-        "ext-redis": "*"
+        "php": ">=5.6.3"
     },
     "require-dev": {
         "phpunit/phpunit": "4.1.0"
     },
     "suggest": {
-        "guzzlehttp/guzzle": "~6.0 for running the blackbox tests."
+        "guzzlehttp/guzzle": "~6.0 for running the blackbox tests.",
+        "ext-redis": "Required if using Redis.",
+        "ext-apc": "Required if using APCu."
     },
     "autoload": {
         "psr-0": {
diff --git a/examples/flush_adapter.php b/examples/flush_adapter.php
new file mode 100644
index 0000000..5c58091
--- /dev/null
+++ b/examples/flush_adapter.php
@@ -0,0 +1,16 @@
+<?php
+require __DIR__ . '/../vendor/autoload.php';
+
+$adapter = $_GET['adapter'];
+
+if ($adapter == 'redis') {
+    define('REDIS_HOST', isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1');
+
+    $redisAdapter = new Prometheus\Storage\Redis(array('host' => REDIS_HOST));
+    $redisAdapter->flushRedis();
+}
+
+if ($adapter == 'apc') {
+    $apcAdapter = new Prometheus\Storage\APC();
+    $apcAdapter->flushAPC();
+}
diff --git a/examples/flush_redis.php b/examples/flush_redis.php
deleted file mode 100644
index f33dde4..0000000
--- a/examples/flush_redis.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-require __DIR__ . '/../vendor/autoload.php';
-
-define('REDIS_HOST', isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1');
-
-$redisAdapter = new Prometheus\Storage\Redis(array('host' => REDIS_HOST));
-$redisAdapter->flushRedis();
diff --git a/examples/metrics.php b/examples/metrics.php
index 7ed5fc9..79c0f92 100644
--- a/examples/metrics.php
+++ b/examples/metrics.php
@@ -6,8 +6,16 @@
 use Prometheus\RenderTextFormat;
 use Prometheus\Storage\Redis;
 
-Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
-$registry = CollectorRegistry::getDefault();
+$adapter = $_GET['adapter'];
+
+if ($adapter == 'redis') {
+    Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
+    $adapter = new Prometheus\Storage\Redis();
+}
+if ($adapter == 'apc') {
+    $adapter = new Prometheus\Storage\APC();
+}
+$registry = new CollectorRegistry($adapter);
 $renderer = new RenderTextFormat();
 $result = $renderer->render($registry->getMetricFamilySamples());
 
diff --git a/examples/some_counter.php b/examples/some_counter.php
index 5851449..738ff22 100644
--- a/examples/some_counter.php
+++ b/examples/some_counter.php
@@ -7,8 +7,16 @@
 
 error_log('c='. $_GET['c']);
 
-Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
-$registry = CollectorRegistry::getDefault();
+$adapter = $_GET['adapter'];
+
+if ($adapter == 'redis') {
+    Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
+    $adapter = new Prometheus\Storage\Redis();
+}
+if ($adapter == 'apc') {
+    $adapter = new Prometheus\Storage\APC();
+}
+$registry = new CollectorRegistry($adapter);
 
 $counter = $registry->registerCounter('test', 'some_counter', 'it increases', ['type']);
 $counter->incBy($_GET['c'], ['blue']);
diff --git a/examples/some_gauge.php b/examples/some_gauge.php
index 14f1553..65aecc6 100644
--- a/examples/some_gauge.php
+++ b/examples/some_gauge.php
@@ -8,8 +8,16 @@
 
 error_log('c='. $_GET['c']);
 
-Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
-$registry = CollectorRegistry::getDefault();
+$adapter = $_GET['adapter'];
+
+if ($adapter == 'redis') {
+    Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
+    $adapter = new Prometheus\Storage\Redis();
+}
+if ($adapter == 'apc') {
+    $adapter = new Prometheus\Storage\APC();
+}
+$registry = new CollectorRegistry($adapter);
 
 $gauge = $registry->registerGauge('test', 'some_gauge', 'it sets', ['type']);
 $gauge->set($_GET['c'], ['blue']);
diff --git a/examples/some_histogram.php b/examples/some_histogram.php
index ff2a60a..684f9f1 100644
--- a/examples/some_histogram.php
+++ b/examples/some_histogram.php
@@ -7,8 +7,16 @@
 
 error_log('c='. $_GET['c']);
 
-Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
-$registry = CollectorRegistry::getDefault();
+$adapter = $_GET['adapter'];
+
+if ($adapter == 'redis') {
+    Redis::setDefaultOptions(array('host' => isset($_SERVER['REDIS_HOST']) ? $_SERVER['REDIS_HOST'] : '127.0.0.1'));
+    $adapter = new Prometheus\Storage\Redis();
+}
+if ($adapter == 'apc') {
+    $adapter = new Prometheus\Storage\APC();
+}
+$registry = new CollectorRegistry($adapter);
 
 $histogram = $registry->registerHistogram('test', 'some_histogram', 'it observes', ['type'], [0.1, 1, 2, 3.5, 4, 5, 6, 7, 8, 9]);
 $histogram->observe($_GET['c'], ['blue']);
diff --git a/php-fpm/Dockerfile b/php-fpm/Dockerfile
index 71fe82c..0fbe56c 100644
--- a/php-fpm/Dockerfile
+++ b/php-fpm/Dockerfile
@@ -1,5 +1,6 @@
 FROM php:5.6-fpm
 
 RUN pecl install redis-2.2.8 && docker-php-ext-enable redis
+RUN pecl install apcu-4.0.11 && docker-php-ext-enable apcu
 
 COPY www.conf /usr/local/etc/php-fpm.d/
diff --git a/src/Prometheus/Storage/APC.php b/src/Prometheus/Storage/APC.php
new file mode 100644
index 0000000..b5a9c4b
--- /dev/null
+++ b/src/Prometheus/Storage/APC.php
@@ -0,0 +1,292 @@
+<?php
+
+
+namespace Prometheus\Storage;
+
+
+use Prometheus\MetricFamilySamples;
+
+class APC implements Adapter
+{
+    const PROMETHEUS_PREFIX = 'prom';
+
+    /**
+     * @return MetricFamilySamples[]
+     */
+    public function collect()
+    {
+        $metrics = $this->collectHistograms();
+        $metrics = array_merge($metrics, $this->collectGauges());
+        $metrics = array_merge($metrics, $this->collectCounters());
+        return $metrics;
+    }
+
+    public function updateHistogram(array $data)
+    {
+        // Initialize the sum
+        $sumKey = $this->histogramBucketValueKey($data, 'sum');
+        $new = apc_add($sumKey, $this->toInteger(0));
+
+        // If sum does not exist, assume a new histogram and store the metadata
+        if ($new) {
+            apc_store($this->metaKey($data), json_encode($this->metaData($data)));
+        }
+
+        // Atomically increment the sum
+        // Taken from https://github.com/prometheus/client_golang/blob/66058aac3a83021948e5fb12f1f408ff556b9037/prometheus/value.go#L91
+        $done = false;
+        while (!$done) {
+            $old = apc_fetch($sumKey);
+            $done = apc_cas($sumKey, $old, $this->toInteger($this->fromInteger($old) + $data['value']));
+        }
+
+        // Figure out in which bucket the observation belongs
+        $bucketToIncrease = '+Inf';
+        foreach ($data['buckets'] as $bucket) {
+            if ($data['value'] <= $bucket) {
+                $bucketToIncrease = $bucket;
+                break;
+            }
+        }
+
+        // Initialize and increment the bucket
+        apc_add($this->histogramBucketValueKey($data, $bucketToIncrease), 0);
+        apc_inc($this->histogramBucketValueKey($data, $bucketToIncrease));
+    }
+
+    public function updateGauge(array $data)
+    {
+        $valueKey = $this->valueKey($data);
+        if ($data['command'] == Adapter::COMMAND_SET) {
+            apc_store($valueKey, $this->toInteger($data['value']));
+            apc_store($this->metaKey($data), json_encode($this->metaData($data)));
+        } else {
+            $new = apc_add($valueKey, $this->toInteger(0));
+            if ($new) {
+                apc_store($this->metaKey($data), json_encode($this->metaData($data)));
+            }
+            // Taken from https://github.com/prometheus/client_golang/blob/66058aac3a83021948e5fb12f1f408ff556b9037/prometheus/value.go#L91
+            $done = false;
+            while (!$done) {
+                $old = apc_fetch($valueKey);
+                $done = apc_cas($valueKey, $old, $this->toInteger($this->fromInteger($old) + $data['value']));
+            }
+        }
+    }
+
+    public function updateCounter(array $data)
+    {
+        $new = apc_add($this->valueKey($data), 0);
+        if ($new) {
+            apc_store($this->metaKey($data), json_encode($this->metaData($data)));
+        }
+        apc_inc($this->valueKey($data), $data['value']);
+    }
+
+    public function flushAPC()
+    {
+       apc_clear_cache('user');
+    }
+
+    /**
+     * @param array $data
+     * @return string
+     */
+    private function metaKey(array $data)
+    {
+        return implode(':', array(self::PROMETHEUS_PREFIX, $data['type'], $data['name'], 'meta'));
+    }
+
+    /**
+     * @param array $data
+     * @return string
+     */
+    private function valueKey(array $data)
+    {
+        return implode(':', array(self::PROMETHEUS_PREFIX, $data['type'], $data['name'], json_encode($data['labelValues']), 'value'));
+    }
+
+    /**
+     * @param array $data
+     * @return string
+     */
+    private function histogramBucketValueKey(array $data, $bucket)
+    {
+        return implode(':', array(self::PROMETHEUS_PREFIX, $data['type'], $data['name'], json_encode($data['labelValues']), $bucket, 'value'));
+    }
+
+    /**
+     * @param array $data
+     * @return array
+     */
+    private function metaData(array $data)
+    {
+        $metricsMetaData = $data;
+        unset($metricsMetaData['value']);
+        unset($metricsMetaData['command']);
+        unset($metricsMetaData['labelValues']);
+        return $metricsMetaData;
+    }
+
+    /**
+     * @return array
+     */
+    private function collectCounters()
+    {
+        $counters = array();
+        foreach (new \APCIterator('user', '/^prom:counter:.*:meta/') as $counter) {
+            $metaData = json_decode($counter['value'], true);
+            $data = array(
+                'name' => $metaData['name'],
+                'help' => $metaData['help'],
+                'type' => $metaData['type'],
+                'labelNames' => $metaData['labelNames'],
+            );
+            foreach (new \APCIterator('user', '/^prom:counter:' . $metaData['name'] . ':.*:value/') as $value) {
+                $parts = explode(':', $value['key']);
+                $labelValues = $parts[3];
+                $data['samples'][] = array(
+                    'name' => $metaData['name'],
+                    'labelNames' => array(),
+                    'labelValues' => json_decode($labelValues),
+                    'value' => $value['value']
+                );
+            }
+            $this->sortSamples($data['samples']);
+            $counters[] = new MetricFamilySamples($data);
+        }
+        return $counters;
+    }
+
+    /**
+ * @return array
+ */
+    private function collectGauges()
+    {
+        $gauges = array();
+        foreach (new \APCIterator('user', '/^prom:gauge:.*:meta/') as $gauge) {
+            $metaData = json_decode($gauge['value'], true);
+            $data = array(
+                'name' => $metaData['name'],
+                'help' => $metaData['help'],
+                'type' => $metaData['type'],
+                'labelNames' => $metaData['labelNames'],
+            );
+            foreach (new \APCIterator('user', '/^prom:gauge:' . $metaData['name'] . ':.*:value/') as $value) {
+                $parts = explode(':', $value['key']);
+                $labelValues = $parts[3];
+                $data['samples'][] = array(
+                    'name' => $metaData['name'],
+                    'labelNames' => array(),
+                    'labelValues' => json_decode($labelValues),
+                    'value' => $this->fromInteger($value['value'])
+                );
+            }
+
+            $this->sortSamples($data['samples']);
+            $gauges[] = new MetricFamilySamples($data);
+        }
+        return $gauges;
+    }
+
+    /**
+     * @return array
+     */
+    private function collectHistograms()
+    {
+        $histograms = array();
+        foreach (new \APCIterator('user', '/^prom:histogram:.*:meta/') as $histogram) {
+            $metaData = json_decode($histogram['value'], true);
+            $data = array(
+                'name' => $metaData['name'],
+                'help' => $metaData['help'],
+                'type' => $metaData['type'],
+                'labelNames' => $metaData['labelNames'],
+                'buckets' => $metaData['buckets']
+            );
+
+            // Add the Inf bucket so we can compute it later on
+            $data['buckets'][] = '+Inf';
+
+            $histogramBuckets = array();
+            foreach (new \APCIterator('user', '/^prom:histogram:' . $metaData['name'] . ':.*:value/') as $value) {
+                $parts = explode(':', $value['key']);
+                $labelValues = $parts[3];
+                $bucket = $parts[4];
+                // Key by labelValues
+                $histogramBuckets[$labelValues][$bucket] = $value['value'];
+            }
+
+            // Compute all buckets
+            $labels = array_keys($histogramBuckets);
+            sort($labels);
+            foreach ($labels as $labelValues) {
+                $acc = 0;
+                $decodedLabelValues = json_decode($labelValues);
+                foreach ($data['buckets'] as $bucket) {
+                    $bucket = (string) $bucket;
+                    if (!isset($histogramBuckets[$labelValues][$bucket])) {
+                        $data['samples'][] = array(
+                            'name' => $metaData['name'] . '_bucket',
+                            'labelNames' => array('le'),
+                            'labelValues' => array_merge($decodedLabelValues, array($bucket)),
+                            'value' => $acc
+                        );
+                    } else {
+                        $acc += $histogramBuckets[$labelValues][$bucket];
+                        $data['samples'][] = array(
+                            'name' => $metaData['name'] . '_' . 'bucket',
+                            'labelNames' => array('le'),
+                            'labelValues' => array_merge($decodedLabelValues, array($bucket)),
+                            'value' => $acc
+                        );
+                    }
+                }
+
+                // Add the count
+                $data['samples'][] = array(
+                    'name' => $metaData['name'] . '_count',
+                    'labelNames' => array(),
+                    'labelValues' => $decodedLabelValues,
+                    'value' => $acc
+                );
+
+                // Add the sum
+                $data['samples'][] = array(
+                    'name' => $metaData['name'] . '_sum',
+                    'labelNames' => array(),
+                    'labelValues' => $decodedLabelValues,
+                    'value' => $this->fromInteger($histogramBuckets[$labelValues]['sum'])
+                );
+
+            }
+            $histograms[] = new MetricFamilySamples($data);
+        }
+        return $histograms;
+    }
+
+    /**
+     * @param mixed $val
+     * @return int
+     */
+    private function toInteger($val)
+    {
+        return unpack('Q', pack('d', $val))[1];
+    }
+
+    /**
+     * @param mixed $val
+     * @return int
+     */
+    private function fromInteger($val)
+    {
+        return unpack('d', pack('Q', $val))[1];
+    }
+
+    private function sortSamples(array &$samples)
+    {
+        usort($samples, function($a, $b){
+            return strcmp(implode("", $a['labelValues']), implode("", $b['labelValues']));
+        });
+    }
+}
diff --git a/tests/Test/BlackBoxTest.php b/tests/Test/BlackBoxTest.php
index d6da60f..daff9dd 100644
--- a/tests/Test/BlackBoxTest.php
+++ b/tests/Test/BlackBoxTest.php
@@ -12,10 +12,16 @@ class BlackBoxTest extends PHPUnit_Framework_TestCase
      */
     private $client;
 
+    /**
+     * @var string
+     */
+    private $adapter;
+
     public function setUp()
     {
-        $this->client = new Client(['base_uri' => 'http://localhost:8080/']);
-        $this->client->get('/examples/flush_redis.php');
+        $this->adapter = getenv('ADAPTER');
+        $this->client = new Client(['base_uri' => 'http://192.168.59.100:8080/']);
+        $this->client->get('/examples/flush_adapter.php?adapter=' . $this->adapter);
     }
 
     /**
@@ -25,9 +31,9 @@ public function gaugesShouldBeOverwritten()
     {
         $start = microtime(true);
         $promises = [
-            $this->client->getAsync('/examples/some_gauge.php?c=0'),
-            $this->client->getAsync('/examples/some_gauge.php?c=1'),
-            $this->client->getAsync('/examples/some_gauge.php?c=2'),
+            $this->client->getAsync('/examples/some_gauge.php?c=0&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_gauge.php?c=1&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_gauge.php?c=2&adapter=' . $this->adapter),
 
         ];
 
@@ -35,7 +41,7 @@ public function gaugesShouldBeOverwritten()
         $end = microtime(true);
         echo "\ntime: " . ($end - $start) . "\n";
 
-        $metricsResult = $this->client->get('/examples/metrics.php');
+        $metricsResult = $this->client->get('/examples/metrics.php?adapter=' . $this->adapter);
         $body = (string)$metricsResult->getBody();
         echo "\nbody: " . $body . "\n";
         $this->assertThat(
@@ -57,7 +63,7 @@ public function countersShouldIncrementAtomically()
         $promises = [];
         $sum = 0;
         for ($i = 0; $i < 1100; $i++) {
-            $promises[] =  $this->client->getAsync('/examples/some_counter.php?c=' . $i);
+            $promises[] =  $this->client->getAsync('/examples/some_counter.php?c=' . $i . '&adapter=' . $this->adapter);
             $sum += $i;
         }
 
@@ -65,7 +71,7 @@ public function countersShouldIncrementAtomically()
         $end = microtime(true);
         echo "\ntime: " . ($end - $start) . "\n";
 
-        $metricsResult = $this->client->get('/examples/metrics.php');
+        $metricsResult = $this->client->get('/examples/metrics.php?adapter=' . $this->adapter);
         $body = (string)$metricsResult->getBody();
 
         $this->assertThat($body, $this->stringContains('test_some_counter{type="blue"} ' . $sum));
@@ -78,23 +84,23 @@ public function histogramsShouldIncrementAtomically()
     {
         $start = microtime(true);
         $promises = [
-            $this->client->getAsync('/examples/some_histogram.php?c=0'),
-            $this->client->getAsync('/examples/some_histogram.php?c=1'),
-            $this->client->getAsync('/examples/some_histogram.php?c=2'),
-            $this->client->getAsync('/examples/some_histogram.php?c=3'),
-            $this->client->getAsync('/examples/some_histogram.php?c=4'),
-            $this->client->getAsync('/examples/some_histogram.php?c=5'),
-            $this->client->getAsync('/examples/some_histogram.php?c=6'),
-            $this->client->getAsync('/examples/some_histogram.php?c=7'),
-            $this->client->getAsync('/examples/some_histogram.php?c=8'),
-            $this->client->getAsync('/examples/some_histogram.php?c=9'),
+            $this->client->getAsync('/examples/some_histogram.php?c=0&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=1&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=2&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=3&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=4&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=5&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=6&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=7&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=8&adapter=' . $this->adapter),
+            $this->client->getAsync('/examples/some_histogram.php?c=9&adapter=' . $this->adapter),
         ];
 
         Promise\settle($promises)->wait();
         $end = microtime(true);
         echo "\ntime: " . ($end - $start) . "\n";
 
-        $metricsResult = $this->client->get('/examples/metrics.php');
+        $metricsResult = $this->client->get('/examples/metrics.php?adapter=' . $this->adapter);
         $body = (string)$metricsResult->getBody();
 
         $this->assertThat($body, $this->stringContains(<<<EOF
diff --git a/tests/Test/Prometheus/APC/CollectorRegistryTest.php b/tests/Test/Prometheus/APC/CollectorRegistryTest.php
new file mode 100644
index 0000000..c1dfc4b
--- /dev/null
+++ b/tests/Test/Prometheus/APC/CollectorRegistryTest.php
@@ -0,0 +1,16 @@
+<?php
+
+
+namespace Test\Prometheus\APC;
+
+use Prometheus\Storage\APC;
+use Test\Prometheus\AbstractCollectorRegistryTest;
+
+class CollectorRegistryTest extends AbstractCollectorRegistryTest
+{
+    public function configureAdapter()
+    {
+        $this->adapter = new APC();
+        $this->adapter->flushAPC();
+    }
+}
diff --git a/tests/Test/Prometheus/APC/CounterTest.php b/tests/Test/Prometheus/APC/CounterTest.php
new file mode 100644
index 0000000..b8b5c94
--- /dev/null
+++ b/tests/Test/Prometheus/APC/CounterTest.php
@@ -0,0 +1,20 @@
+<?php
+
+
+namespace Test\Prometheus\APC;
+
+use Prometheus\Storage\APC;
+use Test\Prometheus\AbstractCounterTest;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+class CounterTest extends AbstractCounterTest
+{
+
+    public function configureAdapter()
+    {
+        $this->adapter = new APC();
+        $this->adapter->flushAPC();
+    }
+}
diff --git a/tests/Test/Prometheus/APC/GaugeTest.php b/tests/Test/Prometheus/APC/GaugeTest.php
new file mode 100644
index 0000000..18a9dd9
--- /dev/null
+++ b/tests/Test/Prometheus/APC/GaugeTest.php
@@ -0,0 +1,20 @@
+<?php
+
+
+namespace Test\Prometheus\APC;
+
+use Prometheus\Storage\APC;
+use Test\Prometheus\AbstractGaugeTest;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+class GaugeTest extends AbstractGaugeTest
+{
+
+    public function configureAdapter()
+    {
+        $this->adapter = new APC();
+        $this->adapter->flushAPC();
+    }
+}
diff --git a/tests/Test/Prometheus/APC/HistogramTest.php b/tests/Test/Prometheus/APC/HistogramTest.php
new file mode 100644
index 0000000..71651f7
--- /dev/null
+++ b/tests/Test/Prometheus/APC/HistogramTest.php
@@ -0,0 +1,21 @@
+<?php
+
+
+namespace Test\Prometheus\APC;
+
+use Prometheus\Storage\APC;
+use Test\Prometheus\AbstractHistogramTest;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+class HistogramTest extends AbstractHistogramTest
+{
+
+    public function configureAdapter()
+    {
+        $this->adapter = new APC();
+        $this->adapter->flushAPC();
+    }
+}
+
diff --git a/tests/Test/Prometheus/CollectorRegistryTest.php b/tests/Test/Prometheus/AbstractCollectorRegistryTest.php
similarity index 82%
rename from tests/Test/Prometheus/CollectorRegistryTest.php
rename to tests/Test/Prometheus/AbstractCollectorRegistryTest.php
index ba25704..5cfdf82 100644
--- a/tests/Test/Prometheus/CollectorRegistryTest.php
+++ b/tests/Test/Prometheus/AbstractCollectorRegistryTest.php
@@ -9,11 +9,16 @@
 use Prometheus\Exception\MetricsRegistrationException;
 use Prometheus\Histogram;
 use Prometheus\RenderTextFormat;
+use Prometheus\Storage\Adapter;
 use Prometheus\Storage\Redis;
 
-class CollectorRegistryTest extends PHPUnit_Framework_TestCase
+abstract class AbstractCollectorRegistryTest extends PHPUnit_Framework_TestCase
 {
-    private $redisAdapter;
+    /**
+     * @var Adapter
+     */
+    public $adapter;
+
     /**
      * @var RenderTextFormat
      */
@@ -21,31 +26,34 @@ class CollectorRegistryTest extends PHPUnit_Framework_TestCase
 
     public function setUp()
     {
-        $this->redisAdapter = $this->newRedisAdapter();
-        $this->redisAdapter->flushRedis();
+        $this->configureAdapter();
         $this->renderer = new RenderTextFormat();
     }
 
     /**
      * @test
      */
-    public function itShouldSaveGaugesInRedis()
+    public function itShouldSaveGauges()
     {
-        $registry = new CollectorRegistry($this->redisAdapter);
+        $registry = new CollectorRegistry($this->adapter);
 
         $g = $registry->registerGauge('test', 'some_metric', 'this is for testing', array('foo'));
-        $g->set(32, array('lalal'));
-        $g->set(35, array('lalab'));
+        $g->set(35, array('bbb'));
+        $g->set(35, array('ddd'));
+        $g->set(35, array('aaa'));
+        $g->set(35, array('ccc'));
 
 
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry($this->adapter);
         $this->assertThat(
             $this->renderer->render($registry->getMetricFamilySamples()),
             $this->equalTo(<<<EOF
 # HELP test_some_metric this is for testing
 # TYPE test_some_metric gauge
-test_some_metric{foo="lalab"} 35
-test_some_metric{foo="lalal"} 32
+test_some_metric{foo="aaa"} 35
+test_some_metric{foo="bbb"} 35
+test_some_metric{foo="ccc"} 35
+test_some_metric{foo="ddd"} 35
 
 EOF
             )
@@ -55,15 +63,15 @@ public function itShouldSaveGaugesInRedis()
     /**
      * @test
      */
-    public function itShouldSaveCountersInRedis()
+    public function itShouldSaveCounters()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry($this->adapter);
         $metric = $registry->registerCounter('test', 'some_metric', 'this is for testing', array('foo', 'bar'));
         $metric->incBy(2, array('lalal', 'lululu'));
         $registry->getCounter('test', 'some_metric', array('foo', 'bar'))->inc(array('lalal', 'lululu'));
         $registry->getCounter('test', 'some_metric', array('foo', 'bar'))->inc(array('lalal', 'lvlvlv'));
 
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry($this->adapter);
         $this->assertThat(
             $this->renderer->render($registry->getMetricFamilySamples()),
             $this->equalTo(<<<EOF
@@ -80,9 +88,9 @@ public function itShouldSaveCountersInRedis()
     /**
      * @test
      */
-    public function itShouldSaveHistogramsInRedis()
+    public function itShouldSaveHistograms()
     {
-        $registry = new CollectorRegistry($this->redisAdapter);
+        $registry = new CollectorRegistry($this->adapter);
         $metric = $registry->registerHistogram('test', 'some_metric', 'this is for testing', array('foo', 'bar'), array(0.1, 1, 5, 10));
         $metric->observe(2, array('lalal', 'lululu'));
         $registry->getHistogram('test', 'some_metric', array('foo', 'bar'))->observe(7.1, array('lalal', 'lvlvlv'));
@@ -90,7 +98,7 @@ public function itShouldSaveHistogramsInRedis()
         $registry->getHistogram('test', 'some_metric', array('foo', 'bar'))->observe(7.1, array('lalal', 'lululu'));
         $registry->getHistogram('test', 'some_metric', array('foo', 'bar'))->observe(7.1, array('gnaaha', 'hihihi'));
 
-        $registry = new CollectorRegistry($this->redisAdapter);
+        $registry = new CollectorRegistry($this->adapter);
         $this->assertThat(
             $this->renderer->render($registry->getMetricFamilySamples()),
             $this->equalTo(<<<EOF
@@ -128,13 +136,13 @@ public function itShouldSaveHistogramsInRedis()
      */
     public function itShouldSaveHistogramsWithoutLabels()
     {
-        $registry = new CollectorRegistry($this->redisAdapter);
+        $registry = new CollectorRegistry($this->adapter);
         $metric = $registry->registerHistogram('test', 'some_metric', 'this is for testing');
         $metric->observe(2);
         $registry->getHistogram('test', 'some_metric')->observe(13);
         $registry->getHistogram('test', 'some_metric')->observe(7.1);
 
-        $registry = new CollectorRegistry($this->redisAdapter);
+        $registry = new CollectorRegistry($this->adapter);
         $this->assertThat(
             $this->renderer->render($registry->getMetricFamilySamples()),
             $this->equalTo(<<<EOF
@@ -168,7 +176,7 @@ public function itShouldSaveHistogramsWithoutLabels()
      */
     public function itShouldIncreaseACounterWithoutNamespace()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry
             ->registerCounter('', 'some_quick_counter', 'just a quick measurement')
             ->inc();
@@ -191,7 +199,7 @@ public function itShouldIncreaseACounterWithoutNamespace()
      */
     public function itShouldForbidRegisteringTheSameCounterTwice()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->registerCounter('foo', 'metric', 'help');
         $registry->registerCounter('foo', 'metric', 'help');
     }
@@ -202,7 +210,7 @@ public function itShouldForbidRegisteringTheSameCounterTwice()
      */
     public function itShouldForbidRegisteringTheSameCounterWithDifferentLabels()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->registerCounter('foo', 'metric', 'help', array("foo", "bar"));
         $registry->registerCounter('foo', 'metric', 'help', array("spam", "eggs"));
     }
@@ -213,7 +221,7 @@ public function itShouldForbidRegisteringTheSameCounterWithDifferentLabels()
      */
     public function itShouldForbidRegisteringTheSameHistogramTwice()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->registerHistogram('foo', 'metric', 'help');
         $registry->registerHistogram('foo', 'metric', 'help');
     }
@@ -224,7 +232,7 @@ public function itShouldForbidRegisteringTheSameHistogramTwice()
      */
     public function itShouldForbidRegisteringTheSameHistogramWithDifferentLabels()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->registerCounter('foo', 'metric', 'help', array("foo", "bar"));
         $registry->registerCounter('foo', 'metric', 'help', array("spam", "eggs"));
     }
@@ -235,7 +243,7 @@ public function itShouldForbidRegisteringTheSameHistogramWithDifferentLabels()
      */
     public function itShouldForbidRegisteringTheSameGaugeTwice()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->registerGauge('foo', 'metric', 'help');
         $registry->registerGauge('foo', 'metric', 'help');
     }
@@ -246,7 +254,7 @@ public function itShouldForbidRegisteringTheSameGaugeTwice()
      */
     public function itShouldForbidRegisteringTheSameGaugeWithDifferentLabels()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->registerGauge('foo', 'metric', 'help', array("foo", "bar"));
         $registry->registerGauge('foo', 'metric', 'help', array("spam", "eggs"));
     }
@@ -257,12 +265,9 @@ public function itShouldForbidRegisteringTheSameGaugeWithDifferentLabels()
      */
     public function itShouldThrowAnExceptionWhenGettingANonExistentMetric()
     {
-        $registry = new CollectorRegistry($this->newRedisAdapter());
+        $registry = new CollectorRegistry( $this->adapter);
         $registry->getGauge("not_here", "go_away");
     }
 
-    private function newRedisAdapter()
-    {
-        return new Redis(array('host' => REDIS_HOST));
-    }
+    public abstract function configureAdapter();
 }
diff --git a/tests/Test/Prometheus/CounterTest.php b/tests/Test/Prometheus/AbstractCounterTest.php
similarity index 84%
rename from tests/Test/Prometheus/CounterTest.php
rename to tests/Test/Prometheus/AbstractCounterTest.php
index 2273077..92501f5 100644
--- a/tests/Test/Prometheus/CounterTest.php
+++ b/tests/Test/Prometheus/AbstractCounterTest.php
@@ -6,24 +6,20 @@
 use PHPUnit_Framework_TestCase;
 use Prometheus\Counter;
 use Prometheus\MetricFamilySamples;
-use Prometheus\Sample;
-use Prometheus\Storage\InMemory;
-use Prometheus\Storage\Redis;
 
 /**
  * See https://prometheus.io/docs/instrumenting/exposition_formats/
  */
-class CounterTest extends PHPUnit_Framework_TestCase
+abstract class AbstractCounterTest extends PHPUnit_Framework_TestCase
 {
     /**
-     * @var Redis
+     * @var Adapter
      */
-    private $storage;
+    public $adapter;
 
     public function setUp()
     {
-        $this->storage = new Redis(array('host' => REDIS_HOST));
-        $this->storage->flushRedis();
+        $this->configureAdapter();
     }
 
     /**
@@ -31,12 +27,12 @@ public function setUp()
      */
     public function itShouldIncreaseWithLabels()
     {
-        $gauge = new Counter($this->storage, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge = new Counter($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
         $gauge->inc(array('lalal', 'lululu'));
         $gauge->inc(array('lalal', 'lululu'));
         $gauge->inc(array('lalal', 'lululu'));
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -65,10 +61,10 @@ public function itShouldIncreaseWithLabels()
      */
     public function itShouldIncreaseWithoutLabelWhenNoLabelsAreDefined()
     {
-        $gauge = new Counter($this->storage, 'test', 'some_metric', 'this is for testing');
+        $gauge = new Counter($this->adapter, 'test', 'some_metric', 'this is for testing');
         $gauge->inc();
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -97,11 +93,11 @@ public function itShouldIncreaseWithoutLabelWhenNoLabelsAreDefined()
      */
     public function itShouldIncreaseTheCounterByAnArbitraryInteger()
     {
-        $gauge = new Counter($this->storage, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge = new Counter($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
         $gauge->inc(array('lalal', 'lululu'));
         $gauge->incBy(123, array('lalal', 'lululu'));
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -131,7 +127,7 @@ public function itShouldIncreaseTheCounterByAnArbitraryInteger()
      */
     public function itShouldRejectInvalidMetricsNames()
     {
-        new Counter($this->storage, 'test', 'some metric invalid metric', 'help');
+        new Counter($this->adapter, 'test', 'some metric invalid metric', 'help');
     }
 
     /**
@@ -140,6 +136,8 @@ public function itShouldRejectInvalidMetricsNames()
      */
     public function itShouldRejectInvalidLabelNames()
     {
-        new Counter($this->storage, 'test', 'some_metric', 'help', array('invalid label'));
+        new Counter($this->adapter, 'test', 'some_metric', 'help', array('invalid label'));
     }
+
+    public abstract function configureAdapter();
 }
diff --git a/tests/Test/Prometheus/AbstractGaugeTest.php b/tests/Test/Prometheus/AbstractGaugeTest.php
new file mode 100644
index 0000000..175f0b5
--- /dev/null
+++ b/tests/Test/Prometheus/AbstractGaugeTest.php
@@ -0,0 +1,312 @@
+<?php
+
+
+namespace Test\Prometheus;
+
+use PHPUnit_Framework_TestCase;
+use Prometheus\Gauge;
+use Prometheus\MetricFamilySamples;
+use Prometheus\Storage\Adapter;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+abstract class AbstractGaugeTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @var Adapter
+     */
+    public $adapter;
+
+    public function setUp()
+    {
+        $this->configureAdapter();
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldAllowSetWithLabels()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge->set(123, array('lalal', 'lululu'));
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array('foo', 'bar'),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array('lalal', 'lululu'),
+                                    'value' => 123,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+        $this->assertThat($gauge->getHelp(), $this->equalTo('this is for testing'));
+        $this->assertThat($gauge->getType(), $this->equalTo(Gauge::TYPE));
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldAllowSetWithoutLabelWhenNoLabelsAreDefined()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing');
+        $gauge->set(123);
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array(),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array(),
+                                    'value' => 123,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+        $this->assertThat($gauge->getHelp(), $this->equalTo('this is for testing'));
+        $this->assertThat($gauge->getType(), $this->equalTo(Gauge::TYPE));
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldAllowSetWithAFloatValue()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing');
+        $gauge->set(123.5);
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array(),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array(),
+                                    'value' => 123.5,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+        $this->assertThat($gauge->getHelp(), $this->equalTo('this is for testing'));
+        $this->assertThat($gauge->getType(), $this->equalTo(Gauge::TYPE));
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldIncrementAValue()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge->inc(array('lalal', 'lululu'));
+        $gauge->incBy(123, array('lalal', 'lululu'));
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array('foo', 'bar'),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array('lalal', 'lululu'),
+                                    'value' => 124,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldIncrementWithFloatValue()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge->inc(array('lalal', 'lululu'));
+        $gauge->incBy(123.5, array('lalal', 'lululu'));
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array('foo', 'bar'),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array('lalal', 'lululu'),
+                                    'value' => 124.5,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldDecrementAValue()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge->dec(array('lalal', 'lululu'));
+        $gauge->decBy(123, array('lalal', 'lululu'));
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array('foo', 'bar'),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array('lalal', 'lululu'),
+                                    'value' => -124,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldDecrementWithFloatValue()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge->dec(array('lalal', 'lululu'));
+        $gauge->decBy(123, array('lalal', 'lululu'));
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array('foo', 'bar'),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array('lalal', 'lululu'),
+                                    'value' => -124,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function itShouldOverwriteWhenSettingTwice()
+    {
+        $gauge = new Gauge($this->adapter, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
+        $gauge->set(123, array('lalal', 'lululu'));
+        $gauge->set(321, array('lalal', 'lululu'));
+        $this->assertThat(
+            $this->adapter->collect(),
+            $this->equalTo(
+                array(
+                    new MetricFamilySamples(
+                        array(
+                            'name' => 'test_some_metric',
+                            'help' => 'this is for testing',
+                            'type' => Gauge::TYPE,
+                            'labelNames' => array('foo', 'bar'),
+                            'samples' => array(
+                                array(
+                                    'name' => 'test_some_metric',
+                                    'labelNames' => array(),
+                                    'labelValues' => array('lalal', 'lululu'),
+                                    'value' => 321,
+                                )
+                            )
+                        )
+                    )
+                )
+            )
+        );
+    }
+
+    /**
+     * @test
+     * @expectedException \InvalidArgumentException
+     */
+    public function itShouldRejectInvalidMetricsNames()
+    {
+        new Gauge($this->adapter, 'test', 'some metric invalid metric', 'help');
+    }
+
+    /**
+     * @test
+     * @expectedException \InvalidArgumentException
+     */
+    public function itShouldRejectInvalidLabelNames()
+    {
+        new Gauge($this->adapter, 'test', 'some_metric', 'help', array('invalid label'));
+    }
+
+    public abstract function configureAdapter();
+}
diff --git a/tests/Test/Prometheus/HistogramTest.php b/tests/Test/Prometheus/AbstractHistogramTest.php
similarity index 95%
rename from tests/Test/Prometheus/HistogramTest.php
rename to tests/Test/Prometheus/AbstractHistogramTest.php
index 7c3f998..e83ff39 100644
--- a/tests/Test/Prometheus/HistogramTest.php
+++ b/tests/Test/Prometheus/AbstractHistogramTest.php
@@ -6,23 +6,22 @@
 use PHPUnit_Framework_TestCase;
 use Prometheus\Histogram;
 use Prometheus\MetricFamilySamples;
-use Prometheus\Storage\InMemory;
-use Prometheus\Storage\Redis;
+use Prometheus\Storage\Adapter;
+
 
 /**
  * See https://prometheus.io/docs/instrumenting/exposition_formats/
  */
-class HistogramTest extends PHPUnit_Framework_TestCase
+abstract class AbstractHistogramTest extends PHPUnit_Framework_TestCase
 {
     /**
-     * @var Redis
+     * @var Adapter
      */
-    private $storage;
+    public $adapter;
 
     public function setUp()
     {
-        $this->storage = new Redis(array('host' => REDIS_HOST));
-        $this->storage->flushRedis();
+        $this->configureAdapter();
     }
 
     /**
@@ -31,7 +30,7 @@ public function setUp()
     public function itShouldObserveWithLabels()
     {
         $histogram = new Histogram(
-            $this->storage,
+            $this->adapter,
             'test',
             'some_metric',
             'this is for testing',
@@ -41,7 +40,7 @@ public function itShouldObserveWithLabels()
         $histogram->observe(123, array('lalal', 'lululu'));
         $histogram->observe(245, array('lalal', 'lululu'));
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -101,7 +100,7 @@ public function itShouldObserveWithLabels()
     public function itShouldObserveWithoutLabelWhenNoLabelsAreDefined()
     {
         $histogram = new Histogram(
-            $this->storage,
+            $this->adapter,
             'test',
             'some_metric',
             'this is for testing',
@@ -110,7 +109,7 @@ public function itShouldObserveWithoutLabelWhenNoLabelsAreDefined()
         );
         $histogram->observe(245);
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -170,7 +169,7 @@ public function itShouldObserveWithoutLabelWhenNoLabelsAreDefined()
     public function itShouldObserveValuesOfTypeDouble()
     {
         $histogram = new Histogram(
-            $this->storage,
+            $this->adapter,
             'test',
             'some_metric',
             'this is for testing',
@@ -180,7 +179,7 @@ public function itShouldObserveValuesOfTypeDouble()
         $histogram->observe(0.11);
         $histogram->observe(0.3);
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -242,7 +241,7 @@ public function itShouldProvideDefaultBuckets()
         // .005, .01, .025, .05, .075, .1, .25, .5, .75, 1.0, 2.5, 5.0, 7.5, 10.0
 
         $histogram = new Histogram(
-            $this->storage,
+            $this->adapter,
             'test',
             'some_metric',
             'this is for testing',
@@ -252,7 +251,7 @@ public function itShouldProvideDefaultBuckets()
         $histogram->observe(0.11);
         $histogram->observe(0.03);
         $this->assertThat(
-            $this->storage->collect(),
+            $this->adapter->collect(),
             $this->equalTo(
                 array(
                     new MetricFamilySamples(
@@ -378,7 +377,7 @@ public function itShouldProvideDefaultBuckets()
      */
     public function itShouldThrowAnExceptionWhenTheBucketSizesAreNotIncreasing()
     {
-        new Histogram($this->storage, 'test', 'some_metric', 'this is for testing', array(), array(1, 1));
+        new Histogram($this->adapter, 'test', 'some_metric', 'this is for testing', array(), array(1, 1));
     }
 
     /**
@@ -387,7 +386,7 @@ public function itShouldThrowAnExceptionWhenTheBucketSizesAreNotIncreasing()
      */
     public function itShouldThrowAnExceptionWhenThereIsLessThanOneBucket()
     {
-        new Histogram($this->storage, 'test', 'some_metric', 'this is for testing', array(), array());
+        new Histogram($this->adapter, 'test', 'some_metric', 'this is for testing', array(), array());
     }
 
     /**
@@ -396,7 +395,7 @@ public function itShouldThrowAnExceptionWhenThereIsLessThanOneBucket()
      */
     public function itShouldThrowAnExceptionWhenThereIsALabelNamedLe()
     {
-        new Histogram($this->storage, 'test', 'some_metric', 'this is for testing', array('le'), array());
+        new Histogram($this->adapter, 'test', 'some_metric', 'this is for testing', array('le'), array());
     }
 
     /**
@@ -405,7 +404,7 @@ public function itShouldThrowAnExceptionWhenThereIsALabelNamedLe()
      */
     public function itShouldRejectInvalidMetricsNames()
     {
-        new Histogram($this->storage, 'test', 'some invalid metric', 'help', array(), array(1));
+        new Histogram($this->adapter, 'test', 'some invalid metric', 'help', array(), array(1));
     }
 
     /**
@@ -414,6 +413,8 @@ public function itShouldRejectInvalidMetricsNames()
      */
     public function itShouldRejectInvalidLabelNames()
     {
-        new Histogram($this->storage, 'test', 'some_metric', 'help', array('invalid label'), array(1));
+        new Histogram($this->adapter, 'test', 'some_metric', 'help', array('invalid label'), array(1));
     }
+
+    public abstract function configureAdapter();
 }
diff --git a/tests/Test/Prometheus/GaugeTest.php b/tests/Test/Prometheus/GaugeTest.php
deleted file mode 100644
index bbe4cc1..0000000
--- a/tests/Test/Prometheus/GaugeTest.php
+++ /dev/null
@@ -1,180 +0,0 @@
-<?php
-
-
-namespace Test\Prometheus;
-
-use PHPUnit_Framework_TestCase;
-use Prometheus\Gauge;
-use Prometheus\MetricFamilySamples;
-use Prometheus\Sample;
-use Prometheus\Storage\InMemory;
-use Prometheus\Storage\Redis;
-
-/**
- * See https://prometheus.io/docs/instrumenting/exposition_formats/
- */
-class GaugeTest extends PHPUnit_Framework_TestCase
-{
-    /**
-     * @var Redis
-     */
-    private $storage;
-
-    public function setUp()
-    {
-        $this->storage = new Redis(array('host' => REDIS_HOST));
-        $this->storage->flushRedis();
-    }
-
-    /**
-     * @test
-     */
-    public function itShouldAllowSetWithLabels()
-    {
-        $gauge = new Gauge($this->storage, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
-        $gauge->set(123, array('lalal', 'lululu'));
-        $this->assertThat(
-            $this->storage->collect(),
-            $this->equalTo(
-                array(
-                    new MetricFamilySamples(
-                        array(
-                            'name' => 'test_some_metric',
-                            'help' => 'this is for testing',
-                            'type' => Gauge::TYPE,
-                            'labelNames' => array('foo', 'bar'),
-                            'samples' => array(
-                                array(
-                                    'name' => 'test_some_metric',
-                                    'labelNames' => array(),
-                                    'labelValues' => array('lalal', 'lululu'),
-                                    'value' => 123,
-                                )
-                            )
-                        )
-                    )
-                )
-            )
-        );
-        $this->assertThat($gauge->getHelp(), $this->equalTo('this is for testing'));
-        $this->assertThat($gauge->getType(), $this->equalTo(Gauge::TYPE));
-    }
-
-    /**
-     * @test
-     */
-    public function itShouldAllowSetWithoutLabelWhenNoLabelsAreDefined()
-    {
-        $gauge = new Gauge($this->storage, 'test', 'some_metric', 'this is for testing');
-        $gauge->set(123);
-        $this->assertThat(
-            $this->storage->collect(),
-            $this->equalTo(
-                array(
-                    new MetricFamilySamples(
-                        array(
-                            'name' => 'test_some_metric',
-                            'help' => 'this is for testing',
-                            'type' => Gauge::TYPE,
-                            'labelNames' => array(),
-                            'samples' => array(
-                                array(
-                                    'name' => 'test_some_metric',
-                                    'labelNames' => array(),
-                                    'labelValues' => array(),
-                                    'value' => 123,
-                                )
-                            )
-                        )
-                    )
-                )
-            )
-        );
-        $this->assertThat($gauge->getHelp(), $this->equalTo('this is for testing'));
-        $this->assertThat($gauge->getType(), $this->equalTo(Gauge::TYPE));
-    }
-
-    /**
-     * @test
-     */
-    public function itShouldIncrementAValue()
-    {
-        $gauge = new Gauge($this->storage, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
-        $gauge->inc(array('lalal', 'lululu'));
-        $gauge->incBy(123, array('lalal', 'lululu'));
-        $this->assertThat(
-            $this->storage->collect(),
-            $this->equalTo(
-                array(
-                    new MetricFamilySamples(
-                        array(
-                            'name' => 'test_some_metric',
-                            'help' => 'this is for testing',
-                            'type' => Gauge::TYPE,
-                            'labelNames' => array('foo', 'bar'),
-                            'samples' => array(
-                                array(
-                                    'name' => 'test_some_metric',
-                                    'labelNames' => array(),
-                                    'labelValues' => array('lalal', 'lululu'),
-                                    'value' => 124,
-                                )
-                            )
-                        )
-                    )
-                )
-            )
-        );
-    }
-
-    /**
-     * @test
-     */
-    public function itShouldDecrementAValue()
-    {
-        $gauge = new Gauge($this->storage, 'test', 'some_metric', 'this is for testing', array('foo', 'bar'));
-        $gauge->dec(array('lalal', 'lululu'));
-        $gauge->decBy(123, array('lalal', 'lululu'));
-        $this->assertThat(
-            $this->storage->collect(),
-            $this->equalTo(
-                array(
-                    new MetricFamilySamples(
-                        array(
-                            'name' => 'test_some_metric',
-                            'help' => 'this is for testing',
-                            'type' => Gauge::TYPE,
-                            'labelNames' => array('foo', 'bar'),
-                            'samples' => array(
-                                array(
-                                    'name' => 'test_some_metric',
-                                    'labelNames' => array(),
-                                    'labelValues' => array('lalal', 'lululu'),
-                                    'value' => -124,
-                                )
-                            )
-                        )
-                    )
-                )
-            )
-        );
-    }
-
-    /**
-     * @test
-     * @expectedException \InvalidArgumentException
-     */
-    public function itShouldRejectInvalidMetricsNames()
-    {
-        new Gauge($this->storage, 'test', 'some metric invalid metric', 'help');
-    }
-
-    /**
-     * @test
-     * @expectedException \InvalidArgumentException
-     */
-    public function itShouldRejectInvalidLabelNames()
-    {
-        new Gauge($this->storage, 'test', 'some_metric', 'help', array('invalid label'));
-    }
-}
diff --git a/tests/Test/Prometheus/Redis/CollectorRegistryTest.php b/tests/Test/Prometheus/Redis/CollectorRegistryTest.php
new file mode 100644
index 0000000..ed2ad2b
--- /dev/null
+++ b/tests/Test/Prometheus/Redis/CollectorRegistryTest.php
@@ -0,0 +1,16 @@
+<?php
+
+
+namespace Test\Prometheus\Redis;
+
+use Prometheus\Storage\Redis;
+use Test\Prometheus\AbstractCollectorRegistryTest;
+
+class CollectorRegistryTest extends AbstractCollectorRegistryTest
+{
+    public function configureAdapter()
+    {
+        $this->adapter = new Redis(array('host' => REDIS_HOST));
+        $this->adapter->flushRedis();
+    }
+}
diff --git a/tests/Test/Prometheus/Redis/CounterTest.php b/tests/Test/Prometheus/Redis/CounterTest.php
new file mode 100644
index 0000000..0d78272
--- /dev/null
+++ b/tests/Test/Prometheus/Redis/CounterTest.php
@@ -0,0 +1,20 @@
+<?php
+
+
+namespace Test\Prometheus\Redis;
+
+use Prometheus\Storage\Redis;
+use Test\Prometheus\AbstractCounterTest;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+class CounterTest extends AbstractCounterTest
+{
+
+    public function configureAdapter()
+    {
+        $this->adapter = new Redis(array('host' => REDIS_HOST));
+        $this->adapter->flushRedis();
+    }
+}
diff --git a/tests/Test/Prometheus/Redis/GaugeTest.php b/tests/Test/Prometheus/Redis/GaugeTest.php
new file mode 100644
index 0000000..17d0c44
--- /dev/null
+++ b/tests/Test/Prometheus/Redis/GaugeTest.php
@@ -0,0 +1,20 @@
+<?php
+
+
+namespace Test\Prometheus\Redis;
+
+use Prometheus\Storage\Redis;
+use Test\Prometheus\AbstractGaugeTest;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+class GaugeTest extends AbstractGaugeTest
+{
+
+    public function configureAdapter()
+    {
+        $this->adapter = new Redis(array('host' => REDIS_HOST));
+        $this->adapter->flushRedis();
+    }
+}
diff --git a/tests/Test/Prometheus/Redis/HistogramTest.php b/tests/Test/Prometheus/Redis/HistogramTest.php
new file mode 100644
index 0000000..57f73f6
--- /dev/null
+++ b/tests/Test/Prometheus/Redis/HistogramTest.php
@@ -0,0 +1,20 @@
+<?php
+
+
+namespace Test\Prometheus\Redis;
+
+use Prometheus\Storage\Redis;
+use Test\Prometheus\AbstractHistogramTest;
+
+/**
+ * See https://prometheus.io/docs/instrumenting/exposition_formats/
+ */
+class HistogramTest extends AbstractHistogramTest
+{
+
+    public function configureAdapter()
+    {
+        $this->adapter = new Redis(array('host' => REDIS_HOST));
+        $this->adapter->flushRedis();
+    }
+}