[1.7.x] Fixed #22102 -- Made SimpleTestCase tests run before unittest.TestCase ones

Thanks aptiko for the report and Tim Graham for the review.
Backport of 3e3a7372f5 from master.

2 files changed, 61 insertions, 1 deletions

diff --git a/tests/test_discovery_sample/doctests.py b/tests/test_discovery_sample/doctests.py
new file mode 100644
index 0000000000..3d228c6efb
--- /dev/null
+++ b/tests/test_discovery_sample/doctests.py
@@ -0,0 +1,45 @@
+"""
+Doctest example from the official Python documentation.
+https://docs.python.org/3/library/doctest.html
+"""
+
+def factorial(n):
+    """Return the factorial of n, an exact integer >= 0.
+
+    >>> [factorial(n) for n in range(6)]
+    [1, 1, 2, 6, 24, 120]
+    >>> factorial(30)
+    265252859812191058636308480000000
+    >>> factorial(-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: n must be >= 0
+
+    Factorials of floats are OK, but the float must be an exact integer:
+    >>> factorial(30.1)
+    Traceback (most recent call last):
+        ...
+    ValueError: n must be exact integer
+    >>> factorial(30.0)
+    265252859812191058636308480000000
+
+    It must also not be ridiculously large:
+    >>> factorial(1e100)
+    Traceback (most recent call last):
+        ...
+    OverflowError: n too large
+    """
+
+    import math
+    if not n >= 0:
+        raise ValueError("n must be >= 0")
+    if math.floor(n) != n:
+        raise ValueError("n must be exact integer")
+    if n+1 == n:  # catch a value like 1e300
+        raise OverflowError("n too large")
+    result = 1
+    factor = 2
+    while factor <= n:
+        result *= factor
+        factor += 1
+    return result
diff --git a/tests/test_discovery_sample/tests_sample.py b/tests/test_discovery_sample/tests_sample.py
index d538771b0f..eb977e44fb 100644
--- a/tests/test_discovery_sample/tests_sample.py
+++ b/tests/test_discovery_sample/tests_sample.py
@@ -1,6 +1,9 @@
+import doctest
 from unittest import TestCase
 
-from django.test import TestCase as DjangoTestCase
+from django.test import SimpleTestCase, TestCase as DjangoTestCase
+
+from . import doctests
 
 
 class TestVanillaUnittest(TestCase):
@@ -15,5 +18,17 @@ class TestDjangoTestCase(DjangoTestCase):
         self.assertEqual(1, 1)
 
 
+class TestZimpleTestCase(SimpleTestCase):
+    # Z is used to trick this test case to appear after Vanilla in default suite
+
+    def test_sample(self):
+        self.assertEqual(1, 1)
+
+
 class EmptyTestCase(TestCase):
     pass
+
+
+def load_tests(loader, tests, ignore):
+    tests.addTests(doctest.DocTestSuite(doctests))
+    return tests