Differences

This shows you the differences between two versions of the page.

--- pytest_notes [2023/02/01 15:06] – [test a script that prints to stdout] raju
+++ pytest_notes [2023/12/22 18:50] – [run pytest on the current file from the current file] raju
@@ Line 1: / Line 1: @@
+==== tasks ====
+  * [[check if two lists are equal]]
+==== test a function that writes output to a file ====
+<code>
+$ cat write_file.py
+def write_to_file(fname):
+    with open(fname, 'w') as FileObj:
+        FileObj.write('Hello\n')
+def test_write_to_file(tmpdir):
+    file = tmpdir.join('output.txt')
+    write_to_file(file)
+    contents_got = file.read()
+    contents_expected = 'Hello\n'
+    assert contents_got == contents_expected
+</code>
+<code>
+$ python -m pytest write_file.py
+</code>
+Ref:
+  * https://docs.pytest.org/en/7.1.x/how-to/tmp_path.html
+  * https://docs.pytest.org/en/6.2.x/tmpdir.html
+  * https://stackoverflow.com/questions/20531072/writing-a-pytest-function-to-check-outputting-to-a-file-in-python
 ==== test a script that prints to stdout ====
-tags | test case for print
+tags | python test case for print
 snippet 1:
@@ Line 16: / Line 44: @@
 </code>
+Ref:-
   * See https://docs.pytest.org/en/stable/capture.html#accessing-captured-output-from-a-test-function for help on how capsys works in pytest.
-  * https://stackoverflow.com/a/56300627/6305733 - contains a simple example; I first came across capsys here.
+  * https://stackoverflow.com/a/56300627/6305733 - contains a simple example; shows how to use capsys with pytest as well as with unittest; I first came across capsys here.
   * my usages:
     * https://github.com/KamarajuKusumanchi/rutils/blob/master/python3/tests/lib/test_DataFrameUtils.py - tests dataframe printed to stdout
@@ Line 28: / Line 57: @@
 tags | run pytest from main function, pytest run parameterized test
+==== assert actual expected template ====
+template 1
+<code>
+assert Actual == Expected,\
+    'Expected = {}, Actual = {}'.format(Expected, Actual)
+</code>
+template 2
+<code>
+from pandas.util.testing import assert_frame_equal
+assert_frame_equal(df_actual, df_expected)
+</code>
+template 3
+<code>
+import pytest
+@pytest.mark.parametrize('input, expected_output', [
+    ('foo', bar),
+    ('foo2', bar2),
+])
+def test_fancy_func(input, expected_output):
+    got = fancy_func(input)
+    assert got == expected_output, 'Expected = {}, got = {}'.format(expected_output, got)
+</code>
+==== useful links ====
+  * https://docs.pytest.org/en/latest/getting-started.html - Get started on pytest
+  * Source code - https://github.com/pytest-dev/pytest
+  * Official documentation - https://docs.pytest.org
+  * http://pythontesting.net - Brian Okken's website on pytest and code testing in general
+  * To get it from PyPI - https://pypi.python.org/pypi/pytest
+  * T. Ben Thompson's python testing set up - http://tbenthompson.com/post/how_i_test/
+  * https://docs.pytest.org/en/latest/how-to/assert.html#assertions-about-expected-exceptions - shows how to check whether the code is throwing exceptions or not.
+Links related to parameterization:
+  * Parametrizing fixtures and test functions - https://docs.pytest.org/en/latest/parametrize.html#parametrize-basics
+  * Parametrizing tests - https://docs.pytest.org/en/latest/example/parametrize.html
+  * parametrizing tests where functions have default arguments - https://stackoverflow.com/questions/35844791/how-to-write-a-test-for-a-function-with-optional-arguments
+==== books on pytest ====
+  * pytest Quick Start Guide by Bruno Oliveira, published by Packt - https://github.com/PacktPublishing/pytest-Quick-Start-Guide
+  * Python Testing with pytest: Simple, Rapid, Effective, and Scalable 1st Edition by Brian Okken - https://www.amazon.com/Python-Testing-pytest-Effective-Scalable/dp/1680502409/
+==== who wrote pytest ====
+  * https://github.com/pytest-dev/pytest/blob/master/AUTHORS