From fc6208f9a610ad56e23bd1d136e7797fc66916cc Mon Sep 17 00:00:00 2001
From: Marc Neudert <marc.neudert@gmail.com>
Date: Mon, 22 May 2017 20:46:16 +0200
Subject: [PATCH] [refs #7] short-circuits lookups of empty user agents

---
 CHANGELOG.md                      |  7 +++++++
 lib/ua_inspector/pool.ex          | 11 +++++++++++
 test/ua_inspector/parser_test.exs | 17 +++++++++++++----
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3ac7f9c..4afcf225 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,9 +3,16 @@
 ## v0.14.0-dev
 
 - Enhancements
+    - Empty user agents (`""` or `nil`) now return a result without performing
+      an actual lookup. By definition an empty user agent is never detected
+      as a bot
     - System environment configuration can set an optional default value
       to be used if the environment variable is unset
 
+- Bug fixes
+    - Properly handles `nil` values passed to the lookup functions
+      ([#7](https://github.com/elixytics/ua_inspector/issues/7))
+
 ## v0.13.0 (2016-09-08)
 
 - Enhancements
diff --git a/lib/ua_inspector/pool.ex b/lib/ua_inspector/pool.ex
index 777d3117..92d59d1b 100644
--- a/lib/ua_inspector/pool.ex
+++ b/lib/ua_inspector/pool.ex
@@ -3,6 +3,9 @@ defmodule UAInspector.Pool do
   Connects the plain UAInspector interface with the underlying pool.
   """
 
+  alias UAInspector.Result
+
+
   @pool_name    :ua_inspector_pool
   @pool_options [
     name:          { :local, @pool_name },
@@ -28,6 +31,8 @@ defmodule UAInspector.Pool do
   Sends a bot check request to a pool worker.
   """
   @spec bot?(String.t) :: boolean
+  def bot?(nil), do: false
+  def bot?(""),  do: false
   def bot?(ua) do
     :poolboy.transaction(
       @pool_name,
@@ -39,6 +44,8 @@ defmodule UAInspector.Pool do
   Sends a HbbTV check request to a pool worker..
   """
   @spec hbbtv?(String.t) :: false | String.t
+  def hbbtv?(nil), do: false
+  def hbbtv?(""),  do: false
   def hbbtv?(ua) do
     :poolboy.transaction(
       @pool_name,
@@ -50,6 +57,8 @@ defmodule UAInspector.Pool do
   Sends a parse request to a pool worker.
   """
   @spec parse(String.t) :: map
+  def parse(nil), do: %Result{ user_agent: nil }
+  def parse(""),  do: %Result{ user_agent: "" }
   def parse(ua) do
     :poolboy.transaction(
       @pool_name,
@@ -61,6 +70,8 @@ defmodule UAInspector.Pool do
   Sends a client parse request to a pool worker.
   """
   @spec parse_client(String.t) :: map
+  def parse_client(nil), do: %Result{ user_agent: nil }
+  def parse_client(""),  do: %Result{ user_agent: "" }
   def parse_client(ua) do
     :poolboy.transaction(
       @pool_name,
diff --git a/test/ua_inspector/parser_test.exs b/test/ua_inspector/parser_test.exs
index 725bafd7..dd9604c1 100644
--- a/test/ua_inspector/parser_test.exs
+++ b/test/ua_inspector/parser_test.exs
@@ -14,10 +14,8 @@ defmodule UAInspector.ParserTest do
   end
 
   test "parse empty" do
-    agent  = ""
-    parsed = %Result{ user_agent: agent }
-
-    assert parsed == UAInspector.parse(agent)
+    assert UAInspector.parse(nil) == %Result{ user_agent: nil }
+    assert UAInspector.parse("")  == %Result{ user_agent: "" }
   end
 
   test "parse unknown" do
@@ -29,11 +27,17 @@ defmodule UAInspector.ParserTest do
 
 
   test "bot?" do
+    refute UAInspector.bot?(nil)
+    refute UAInspector.bot?("")
+
     assert UAInspector.bot?("generic crawler agent")
     refute UAInspector.bot?("regular user agent")
   end
 
   test "hbbtv?" do
+    refute UAInspector.hbbtv?(nil)
+    refute UAInspector.hbbtv?(nil)
+
     assert "1.1.1" == UAInspector.hbbtv?("agent containing HbbTV/1.1.1 (; ;) information")
     refute UAInspector.hbbtv?("generic user agent")
   end
@@ -56,4 +60,9 @@ defmodule UAInspector.ParserTest do
 
     assert parsed == UAInspector.parse_client(agent)
   end
+
+  test "parse_client empty" do
+    assert UAInspector.parse_client(nil) == %Result{ user_agent: nil }
+    assert UAInspector.parse_client("")  == %Result{ user_agent: "" }
+  end
 end