moves pytest from scipy

Author: jiffyclub

05-pytest.md

@@ -1,16 +1,16 @@
 ---
 layout: page
 title: Testing
-subtitle: Running Tests with Nose
+subtitle: Running Tests with pytest
 minutes: 10
 ---
 > ## Learning Objectives {.objectives}
-> 
-> -   Understand how to run a test suite using the nose framework
-> -   Understand how to read the output of a nose test suite
+>
+> -   Understand how to run a test suite using the pytest framework
+> -   Understand how to read the output of a pytest test suite
 
 
-We created a suite of tests for our mean function, but it was annoying to run 
+We created a suite of tests for our mean function, but it was annoying to run
 them one at a time. It would be a lot better if there were some way to run them
 all at once, just reporting which tests fail and which succeed.
 
@@ -54,71 +54,73 @@ def test_complex():
 ~~~
 
 Once these tests are written in a file called `test_mean.py`, the command
-"nosetests" can be called from the directory containing the tests:
+`py.test` can be called from the directory containing the tests:
 
 ~~~ {.bash}
-$ nosetests
+$ py.test
 ~~~
 ~~~ {.output}
-....F
-======================================================================
-FAIL: test_mean.test_complex
-----------------------------------------------------------------------
-Traceback (most recent call last):
-  File "/Users/khuff/anaconda/envs/py3k/lib/python3.3/site-packages/nose/case.py", line 198, in runTest
-    self.test(*self.arg)
-  File "/Users/khuff/repos/2015-06-04-berkeley/testing/test_mean.py", line 34, in test_complex
-    assert obs == exp
-AssertionError
+collected 5 items
+
+test_mean.py ....F
+
+================================== FAILURES ===================================
+________________________________ test_complex _________________________________
 
-----------------------------------------------------------------------
-Ran 5 tests in 3.746s
+    def test_complex():
+        # given that complex numbers are an unordered field
+        # the arithmetic mean of complex numbers is meaningless
+        num_list = [2 + 3j, 3 + 4j, -32 - 2j]
+        obs = mean(num_list)
+        exp = NotImplemented
+>       assert obs == exp
+E       assert (-9+1.6666666666666667j) == NotImplemented
 
-FAILED (failures=1)
+test_mean.py:34: AssertionError
+===================== 1 failed, 4 passed in 2.71 seconds ======================
 ~~~
 
-In the above case, the python nose package 'sniffed-out' the tests in the
+In the above case, the pytest package 'sniffed-out' the tests in the
 directory and ran them together to produce a report of the sum of the files and
 functions matching the regular expression `[Tt]est[-_]*`.
 
 
 The major boon a testing framework provides is exactly that, a utility to find and run the
-tests automatically. With `nose`, this is the command-line tool called
-_nosetests_.  When _nosetests_ is run, it will search all the directories whose names start or
-end with the word _test_, find all of the Python modules in these directories
-whose names
-start or end with _test_, import them, and run all of the functions and classes
-whose names start or end with _test_. In fact, `nose` looks for any names
-that match the regular expression `'(?:^|[\\b_\\.-])[Tt]est'`.
+tests automatically. With pytest, this is the command-line tool called
+`py.test`.  When `py.test` is run, it will search all directories below where it was called,
+find all of the Python files in these directories whose names
+start or end with `test`, import them, and run all of the functions and classes
+whose names start with `test` or `Test`.
 This automatic registration of test code saves tons of human time and allows us to
 focus on what is important: writing more tests.
 
-When you run _nosetests_, it will print a dot (`.`) on the screen for every test
+When you run `py.test`, it will print a dot (`.`) on the screen for every test
 that passes,
-an `F` for every test that fails, and an `E` for every test were there was an
-unexpected error. In rarer situations you may also see an `S` indicating a
-skipped tests (because the test is not applicable on your system) or a `K` for a known
-failure (because the developers could not fix it promptly). After the dots, _nosetests_
-will print summary information. 
+an `F` for every test that fails or where there was an unexpected error.
+In rarer situations you may also see an `s` indicating a
+skipped tests (because the test is not applicable on your system) or a `x` for a known
+failure (because the developers could not fix it promptly). After the dots, pytest
+will print summary information.
 
 
 > ## Fix The Failing Code {.challenge}
 >
-> Without changing the tests, alter the mean.py file from the previous section until it passes. 
-> When it passes, _nosetests_ will produce results like the following:
+> Without changing the tests, alter the mean.py file from the previous section until it passes.
+> When it passes, `py.test` will produce results like the following:
 >
 > ~~~ {.bash}
-> $ nosetests
+> $ py.test
 > ~~~
 > ~~~ {.output}
-> .....
-> 
-> Ran 5 tests in 3.746s
+> collected 5 items
 >
-> OK
-> ~~~
+> test_mean.py .....
+>
+> ========================== 5 passed in 2.68 seconds ===========================
 
-As we write more code, we would write more tests, and _nosetests_ would produce
+As we write more code, we would write more tests, and pytest would produce
 more dots.  Each passing test is a small, satisfying reward for having written
 quality scientific software. Now that you know how to write tests, let's go
 into what can go wrong.
+
+