Differences between revisions 1 and 13 (spanning 12 versions)

Python Unittest

unittest is a module for unit testing code. It is by design a basic and minimal tool; it was designed for use within Python and requiring no external libraries or tools.

Contents

Python Unittest

Module

Usage

import unittest

class Test1(unittest.TestCase):
    """This is a class docstring."""

    def test_1(self):
        #This will print "test_1 (__main__.Test1) ... ok"
        return

    def test_2(self):
        #This will print "test_1 (__main__.Test1) ... FAIL"
        self.fail()

    def test_3(self):
        #This will print "test_3 (__main__.Test1) ... ERROR"
        raise AttributeError

    @u.skip('foo bar')
    def test_4(self):
        #This will print "test_3 (__main__.Test1) ... skipped 'foo bar'"
        return

if __name__ == '__main__':
    unittest.main()

Any methods with a docstring print both the method's name and the docstring.

All failures or errors print tracebacks, the only difference being the label ('FAIL' or 'ERROR').

Setup and Teardown

The most common reason for grouping a set of tests into a test case is shared objects. These can be generated using the TestCase.setUp() method. (A tearDown() method is also available if needed.)

class TestWidget(unittest.TestCase):

    def setUp(self):
        self.widget = Widget('The widget')\

    def tearDown(self):
        self.widget.dispose()

Subtests

Sometimes a test needs to be run iteratively, as to test multiple possible inputs. Rather than requiring redundant coding, the subtests context will provide this functionality.

class TestEven(unittest.TestCase):

    def test_1(self):
        for i in range(0, 6):
            with self.subTest(i=i):
                self.assertEqual(i % 2, 0)

The i=i may seem redundant, but it will cause the subtest's value of i to print on execution.

Conditional Testing

Tests can be skipped conditionally. This can be used to prevent trivial test failures.

class TestVersion(unittest.TestCase):

    @unittest.skipIf(mylib.__version__ < (1, 3))
    def test_1(self):
        return

Test Methods

Method	Equivalent to...	Usage
`assertEqual`	`a == b`	`self.assertEqual(a,b,msg=m)`
`assertNotEqual`	`a != b`	`self.assertNotEqual(a,b,msg=m)`
`assertGreater`	`a > b`	`self.assertGreater(a,b,msg=m)`
`assertGreaterEqual`	`a >= b`	`self.assertGreaterEqual(a,b,msg=m)`
`assertLesser`	`a < b`	`self.assertLesser(a,b,msg=m)`
`assertLesserEqual`	`a <= b`	`self.assertLesserEqual(a,b,msg=m)`
`assertTrue`	`bool(a) == True`	`self.assertTrue(a,msg=m)`
`assertFalse`	`bool(a) == False`	`self.assertFalse(a,msg=m)`
`assertIs`	`a is b`	`self.assertIs(a,b,msg=m)`
`assertIsNot`	`a is not`	`self.assertIsNot(a,b,msg=m)`
`assertIsNone`	`a is None`	`self.assertIsNone(a,b,msg=m)`
`assertIsNotNone`	`a is not None`	`self.assertIsNotNone(a,b,msg=m)`
`assertIn`	`a in b`	`self.assertIn(a,b,msg=m)`
`assertNotIn`	`a not in b`	`self.assertNotIn(a,b,msg=m)`
`assertRegex`	`re.search(b,a)`	`self.assertRegex(a,b)`
`assertNotRegex`	`not re.search(b,a)`	`self.assertNotRegex(a,b)`
`assertIsInstance`	`isinstance(a,b)`	`self.assertIsInstance(a,b,msg=m)`
`assertIsNotInstance`	`not isinstance(a,b)`	`self.assertIsNotInstance(a,b,msg=m)`
`assertRaises`		`with self.assertRaises(e,msg=m): ...`

CLI Execution

Verbosity is set with --quiet (-q) and --verbose (-v) flags.

The discover subcommand searches for files names matching the pattern test*.py. A search directory can be optionally supplied using --start-directory (-s). An alternate pattern can be optionally supplied using --pattern (-p).

$ python -m unittest discover -s tests/ -v

Writing Unit Tests

Bad File Inputs

To create a file with a bad encoding, try:

def write_bad_file(fn):
    with open(fn, 'w') as f:
        f.write('fooß'.encode('utf-8'))
        f.write('barß'.encode('cp1252'))

-  ⇤ ← Revision 1 as of 2020-05-14 18:26:27 → 
  Size: 3542
  Editor: DominicRicottone
  Comment:
+   ← Revision 13 as of 2023-06-15 18:41:57 → ⇥
  Size: 5054
  Editor: DominicRicottone
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-= Python UnitTest =
+= Python Unittest =
 Line 3:
-Python has a built-in test suite library. It is rudimentary, but requires no external libraries or tools.
+'''`unittest`''' is a module for unit testing code. It is ''by design'' a basic and minimal tool; it was designed for use within Python and requiring no external libraries or tools.
 Line 11:
-== Test Cases ==
+== Module ==

=== Usage ===
-Line 14:
+Line 16:
+import unittest
-Line 15:
+Line 18:
+class Test1(unittest.TestCase):
    """This is a class docstring."""

    def test_1(self):
        #This will print "test_1 (__main__.Test1) ... ok"
        return

    def test_2(self):
        #This will print "test_1 (__main__.Test1) ... FAIL"
        self.fail()

    def test_3(self):
        #This will print "test_3 (__main__.Test1) ... ERROR"
        raise AttributeError

    @u.skip('foo bar')
    def test_4(self):
        #This will print "test_3 (__main__.Test1) ... skipped 'foo bar'"
        return

if __name__ == '__main__':
    unittest.main()
-Line 17:
+Line 42:
+Any methods with a docstring print both the method's name and the docstring.
-Line 18:
+Line 44:
-=== Setup and Teardown ===
+All failures or errors print tracebacks, the only difference being the label ('FAIL' or 'ERROR').



==== Setup and Teardown ====
-Line 34:
+Line 64:
-=== Subtests ===
+==== Subtests ====
-Line 51:
+Line 81:
-=== Conditional Testing ===
+==== Conditional Testing ====
-Line 67:
+Line 97:
-== Test Methods ==
+=== Test Methods ===
-Line 88:
+Line 118:
-||`assertRaises`        ||                       ||`with self.assertRaises(e,msg=m):`    ||
+||`assertRaises`        ||                       ||`with self.assertRaises(e,msg=m): ...`||
-Line 94:
+Line 124:
-== CLI Execution ==
+=== CLI Execution ===
-Line 96:
+Line 126:
-Verbosity is set with `-q` and `-v` flags.
+Verbosity is set with `--quiet` (`-q`) and `--verbose` (`-v`) flags.
-Line 98:
+Line 128:
-The `discover` subcommand searches for files names as `test_*.py`. A search directory can be supplied additionally.
+The `discover` subcommand searches for files names matching the pattern `test*.py`. A search directory can be optionally supplied using `--start-directory` (`-s`). An alternate pattern can be optionally supplied using `--pattern` (`-p`).
-Line 101:
+Line 131:
-$ python -m unittest discover -s tests/
+$ python -m unittest discover -s tests/ -v
-Line 103:
+Line 133:
+----



== Writing Unit Tests ==

=== Bad File Inputs ===

To create a file with a bad encoding, try:

{{{
def write_bad_file(fn):
    with open(fn, 'w') as f:
        f.write('fooß'.encode('utf-8'))
        f.write('barß'.encode('cp1252'))
}}}

----



== See also ==

[[https://docs.python.org/3/library/unittest.html|Python unittest module documentation]]

[[https://pymotw.com/3/unittest/|Python Module of the Day article for unittest]]

Diff for "Python/Unittest"