Ruby 社区的某些方面一直给我留下深刻印象。两个例子是对测试的承诺和强调入门的容易程度。最好的例子是 Ruby Koans，您可以通过修复测试来学习 Ruby。
有了我们为 Python 准备的出色工具，我们应该能够做得更好。我们可以。使用 Jupyter Notebook、PyHamcrest 和一点点类似胶带的代码，我们可以制作一个教程，其中包含教学、可工作的代码和需要修复的代码。
首先，是一些胶带代码。通常，您使用一些不错的命令行测试运行器（如 pytest 或 virtue）进行测试。通常，您甚至不直接运行它。您使用像 tox 或 nox 这样的工具来运行它。但是，对于 Jupyter，您需要编写一个小型的工具，可以直接在单元格中运行测试。
幸运的是，这个工具很短，即使不简单：
import unittest
def run_test(klass):
suite = unittest.TestLoader().loadTestsFromTestCase(klass)
unittest.TextTestRunner(verbosity=2).run(suite)
return klass现在工具完成了，是时候进行第一个练习了。
在教学中，从小处着手，进行一个简单的练习来建立信心总是一个好主意。
那么为什么不修复一个非常简单的测试呢？
@run_test
class TestNumbers(unittest.TestCase):
def test_equality(self):
expected_value = 3 # Only change this line
self.assertEqual(1+1, expected_value) test_equality (__main__.TestNumbers) ... FAIL
======================================================================
FAIL: test_equality (__main__.TestNumbers)
----------------------------------------------------------------------
Traceback (most recent call last):
File "<ipython-input-7-5ebe25bc00f3>", line 6, in test_equality
self.assertEqual(1+1, expected_value)
AssertionError: 2 != 3
----------------------------------------------------------------------
Ran 1 test in 0.002s
FAILED (failures=1)仅更改此行 是对学生有用的标记。它准确地显示了需要更改的内容。否则，学生可以通过将第一行更改为 return 来修复测试。
在这种情况下，修复很容易：
@run_test
class TestNumbers(unittest.TestCase):
def test_equality(self):
expected_value = 2 # Fixed this line
self.assertEqual(1+1, expected_value) test_equality (__main__.TestNumbers) ... ok
----------------------------------------------------------------------
Ran 1 test in 0.002s
OK但是，很快，unittest 库的原生断言将被证明不足。在 pytest 中，这通过重写 assert 中的字节码以使其具有神奇的属性和各种启发式方法来解决。这在 Jupyter notebook 中不容易实现。是时候挖掘出一个好的断言库了：PyHamcrest
from hamcrest import *@run_test
class TestList(unittest.TestCase):
def test_equality(self):
things = [1,
5, # Only change this line
3]
assert_that(things, has_items(1, 2, 3)) test_equality (__main__.TestList) ... FAIL
======================================================================
FAIL: test_equality (__main__.TestList)
----------------------------------------------------------------------
Traceback (most recent call last):
File "<ipython-input-11-96c91225ee7d>", line 8, in test_equality
assert_that(things, has_items(1, 2, 3))
AssertionError:
Expected: (a sequence containing <1> and a sequence containing <2> and a sequence containing <3>)
but: a sequence containing <2> was <[1, 5, 3]>
----------------------------------------------------------------------
Ran 1 test in 0.004s
FAILED (failures=1)PyHamcrest 不仅擅长灵活的断言；它还擅长清晰的错误消息。因此，问题显而易见：[1, 5, 3] 不包含 2，而且看起来也很难看
@run_test
class TestList(unittest.TestCase):
def test_equality(self):
things = [1,
2, # Fixed this line
3]
assert_that(things, has_items(1, 2, 3)) test_equality (__main__.TestList) ... ok
----------------------------------------------------------------------
Ran 1 test in 0.001s
OK借助 Jupyter、PyHamcrest 和一点胶带式的测试工具，您可以教授任何适用于单元测试的 Python 主题。
例如，以下内容可以帮助显示 Python 从字符串中剥离空格的不同方法之间的差异
source_string = " hello world "
@run_test
class TestList(unittest.TestCase):
# This one is a freebie: it already works!
def test_complete_strip(self):
result = source_string.strip()
assert_that(result,
all_of(starts_with("hello"), ends_with("world")))
def test_start_strip(self):
result = source_string # Only change this line
assert_that(result,
all_of(starts_with("hello"), ends_with("world ")))
def test_end_strip(self):
result = source_string # Only change this line
assert_that(result,
all_of(starts_with(" hello"), ends_with("world"))) test_complete_strip (__main__.TestList) ... ok
test_end_strip (__main__.TestList) ... FAIL
test_start_strip (__main__.TestList) ... FAIL
======================================================================
FAIL: test_end_strip (__main__.TestList)
----------------------------------------------------------------------
Traceback (most recent call last):
File "<ipython-input-16-3db7465bd5bf>", line 19, in test_end_strip
assert_that(result,
AssertionError:
Expected: (a string starting with ' hello' and a string ending with 'world')
but: a string ending with 'world' was ' hello world '
======================================================================
FAIL: test_start_strip (__main__.TestList)
----------------------------------------------------------------------
Traceback (most recent call last):
File "<ipython-input-16-3db7465bd5bf>", line 14, in test_start_strip
assert_that(result,
AssertionError:
Expected: (a string starting with 'hello' and a string ending with 'world ')
but: a string starting with 'hello' was ' hello world '
----------------------------------------------------------------------
Ran 3 tests in 0.006s
FAILED (failures=2)理想情况下，学生会意识到 .lstrip() 和 .rstrip() 方法可以满足他们的需求。但是，如果他们不这样做，而是尝试在所有地方都使用 .strip()
source_string = " hello world "
@run_test
class TestList(unittest.TestCase):
# This one is a freebie: it already works!
def test_complete_strip(self):
result = source_string.strip()
assert_that(result,
all_of(starts_with("hello"), ends_with("world")))
def test_start_strip(self):
result = source_string.strip() # Changed this line
assert_that(result,
all_of(starts_with("hello"), ends_with("world ")))
def test_end_strip(self):
result = source_string.strip() # Changed this line
assert_that(result,
all_of(starts_with(" hello"), ends_with("world"))) test_complete_strip (__main__.TestList) ... ok
test_end_strip (__main__.TestList) ... FAIL
test_start_strip (__main__.TestList) ... FAIL
======================================================================
FAIL: test_end_strip (__main__.TestList)
----------------------------------------------------------------------
Traceback (most recent call last):
File "<ipython-input-17-6f9cfa1a997f>", line 19, in test_end_strip
assert_that(result,
AssertionError:
Expected: (a string starting with ' hello' and a string ending with 'world')
but: a string starting with ' hello' was 'hello world'
======================================================================
FAIL: test_start_strip (__main__.TestList)
----------------------------------------------------------------------
Traceback (most recent call last):
File "<ipython-input-17-6f9cfa1a997f>", line 14, in test_start_strip
assert_that(result,
AssertionError:
Expected: (a string starting with 'hello' and a string ending with 'world ')
but: a string ending with 'world ' was 'hello world'
----------------------------------------------------------------------
Ran 3 tests in 0.007s
FAILED (failures=2)他们会收到不同的错误消息，表明剥离了太多空格
source_string = " hello world "
@run_test
class TestList(unittest.TestCase):
# This one is a freebie: it already works!
def test_complete_strip(self):
result = source_string.strip()
assert_that(result,
all_of(starts_with("hello"), ends_with("world")))
def test_start_strip(self):
result = source_string.lstrip() # Fixed this line
assert_that(result,
all_of(starts_with("hello"), ends_with("world ")))
def test_end_strip(self):
result = source_string.rstrip() # Fixed this line
assert_that(result,
all_of(starts_with(" hello"), ends_with("world"))) test_complete_strip (__main__.TestList) ... ok
test_end_strip (__main__.TestList) ... ok
test_start_strip (__main__.TestList) ... ok
----------------------------------------------------------------------
Ran 3 tests in 0.005s
OK在一个更真实的教程中，会有更多的示例和更多的解释。这种使用带有工作示例和一些需要修复的示例的 notebook 的技术可以用于实时教学、基于视频的课程，甚至，如果加上更多的文字，学生可以自行完成的教程。
现在走出去分享你的知识吧！
评论已关闭。