add context manager for failed tests

fastcore/_nbdev.py

@@ -17,6 +17,7 @@
          "TEST_IMAGE": "00_test.ipynb",
          "TEST_IMAGE_BW": "00_test.ipynb",
          "test_fig_exists": "00_test.ipynb",
+         "TestFail": "00_test.ipynb",
          "defaults": "01_foundation.ipynb",
          "copy_func": "01_foundation.ipynb",
          "patch_to": "01_foundation.ipynb",

fastcore/test.py

@@ -1,10 +1,11 @@
 # AUTOGENERATED! DO NOT EDIT! File to edit: nbs/00_test.ipynb (unless otherwise specified).
 
 __all__ = ['test_fail', 'test', 'nequals', 'test_eq', 'test_eq_type', 'test_ne', 'is_close', 'test_close', 'test_is',
-           'test_shuffled', 'test_stdout', 'test_warns', 'TEST_IMAGE', 'TEST_IMAGE_BW', 'test_fig_exists']
+           'test_shuffled', 'test_stdout', 'test_warns', 'TEST_IMAGE', 'TEST_IMAGE_BW', 'test_fig_exists', 'TestFail']
 
 # Cell
 from .imports import *
+from .utils import *
 from collections import Counter
 from contextlib import redirect_stdout
 
@@ -95,4 +96,16 @@ def test_warns(f, show=False):
 # Cell
 def test_fig_exists(ax):
     "Test there is a figure displayed in `ax`"
-    assert ax and len(ax.figure.canvas.tostring_argb())
+    assert ax and len(ax.figure.canvas.tostring_argb())
+
+# Cell
+class TestFail:
+    "A context manager to allow you to test if an exception (ex) is raised. Optionally, search the exception's error message with a regex."
+    def __init__(self, ex:Exception, regex:str=None):store_attr()
+    def __enter__(self): pass
+    def __exit__(self, type, value, traceback):
+        if isinstance(value, self.ex):
+            if self.regex:
+                assert re.search(self.regex, ' '.join(value.args)) is not None, f"Did not find regex:{self.regex} in Exception message."
+            return True
+        else: raise TypeError(f"An error of {self.ex} was not raised.")

nbs/02_utils.ipynb

@@ -296,7 +296,7 @@
     {
      "data": {
       "text/plain": [
-       "<__main__._t at 0x7f945b39e070>"
+       "<__main__._t at 0x7fbd57805430>"
       ]
      },
      "execution_count": null,
@@ -2171,7 +2171,7 @@
     {
      "data": {
       "text/plain": [
-       "['h', 'g', 'f', 'b', 'd', 'e', 'a', 'c']"
+       "['h', 'c', 'g', 'd', 'a', 'e', 'b', 'f']"
       ]
      },
      "execution_count": null,
@@ -2964,7 +2964,7 @@
     {
      "data": {
       "text/plain": [
-       "(Path('../fastcore/all.py'), Path('00_test.ipynb'))"
+       "(Path('../fastcore/__init__.py'), Path('00_test.ipynb'))"
       ]
      },
      "execution_count": null,
@@ -3513,7 +3513,7 @@
     {
      "data": {
       "text/plain": [
-       "8"
+       "4"
       ]
      },
      "execution_count": null,
@@ -3645,6 +3645,47 @@
     "    return functools.update_wrapper(_f, f)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "`typed` validates argument types at **runtime**.  This is in contrast to [MyPy](http://mypy-lang.org/) which only offers static type checking.\n",
+    "\n",
+    "For example, a `TypeError` will be raised if we try to pass an integer into the first argument of the below function: "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "@typed\n",
+    "def discount(price:int, pct:float): \n",
+    "    return (1-pct) * price\n",
+    "\n",
+    "with TestFail(TypeError): discount(100.0, .1)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We can also optionally allow multiple types by enumarating the types in a tuple as illustrated below:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def discount(price:(int,float), pct:float): \n",
+    "    return (1-pct) * price\n",
+    "\n",
+    "assert 90.0 == discount(100.0, .1)"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -3654,11 +3695,12 @@
     "@typed\n",
     "def foo(a:int, b:str='a'): return a\n",
     "test_eq(foo(1, '2'), 1)\n",
-    "test_fail(partial(foo, 1, 2))\n",
+    "\n",
+    "with TestFail(TypeError): foo(1,2)\n",
     "\n",
     "@typed\n",
     "def foo()->str: return 1\n",
-    "test_fail(partial(foo))\n",
+    "with TestFail(TypeError): foo()\n",
     "\n",
     "@typed\n",
     "def foo()->str: return '1'\n",
@@ -3791,7 +3833,7 @@
       "text/markdown": [
        "<h4 id=\"ProcessPoolExecutor\" class=\"doc_header\"><code>class</code> <code>ProcessPoolExecutor</code><a href=\"\" class=\"source_link\" style=\"float:right\">[source]</a></h4>\n",
        "\n",
-       "> <code>ProcessPoolExecutor</code>(**`max_workers`**=*`64`*, **`on_exc`**=*`print`*, **`pause`**=*`0`*, **\\*\\*`kwargs`**) :: [`ProcessPoolExecutor`](/utils.html#ProcessPoolExecutor)\n",
+       "> <code>ProcessPoolExecutor</code>(**`max_workers`**=*`4`*, **`on_exc`**=*`print`*, **`pause`**=*`0`*, **\\*\\*`kwargs`**) :: [`ProcessPoolExecutor`](/utils.html#ProcessPoolExecutor)\n",
        "\n",
        "Same as Python's ProcessPoolExecutor, except can pass `max_workers==0` for serial execution"
       ],
@@ -3922,11 +3964,11 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "0 2020-10-08 18:38:18.973557\n",
-      "1 2020-10-08 18:38:19.223553\n",
-      "2 2020-10-08 18:38:19.475253\n",
-      "3 2020-10-08 18:38:19.725614\n",
-      "4 2020-10-08 18:38:19.976216\n"
+      "1 2020-10-12 21:15:11.361062\n",
+      "0 2020-10-12 21:15:11.612469\n",
+      "2 2020-10-12 21:15:11.863159\n",
+      "3 2020-10-12 21:15:12.113859\n",
+      "4 2020-10-12 21:15:12.366331\n"
      ]
     }
    ],