Close #15415: Factor out temp dir helpers to test.support

Patch by Chris Jerdonek

Lib/test/test_support.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 
 import importlib
+import shutil
 import sys
 import os
 import unittest
@@ -88,6 +89,118 @@ class TestSupport(unittest.TestCase):
         s.listen(1)
         s.close()
 
+    # Tests for temp_dir()
+
+    def test_temp_dir(self):
+        """Test that temp_dir() creates and destroys its directory."""
+        parent_dir = tempfile.mkdtemp()
+        parent_dir = os.path.realpath(parent_dir)
+
+        try:
+            path = os.path.join(parent_dir, 'temp')
+            self.assertFalse(os.path.isdir(path))
+            with support.temp_dir(path) as temp_path:
+                self.assertEqual(temp_path, path)
+                self.assertTrue(os.path.isdir(path))
+            self.assertFalse(os.path.isdir(path))
+        finally:
+            shutil.rmtree(parent_dir)
+
+    def test_temp_dir__path_none(self):
+        """Test passing no path."""
+        with support.temp_dir() as temp_path:
+            self.assertTrue(os.path.isdir(temp_path))
+        self.assertFalse(os.path.isdir(temp_path))
+
+    def test_temp_dir__existing_dir__quiet_default(self):
+        """Test passing a directory that already exists."""
+        def call_temp_dir(path):
+            with support.temp_dir(path) as temp_path:
+                raise Exception("should not get here")
+
+        path = tempfile.mkdtemp()
+        path = os.path.realpath(path)
+        try:
+            self.assertTrue(os.path.isdir(path))
+            self.assertRaises(FileExistsError, call_temp_dir, path)
+            # Make sure temp_dir did not delete the original directory.
+            self.assertTrue(os.path.isdir(path))
+        finally:
+            shutil.rmtree(path)
+
+    def test_temp_dir__existing_dir__quiet_true(self):
+        """Test passing a directory that already exists with quiet=True."""
+        path = tempfile.mkdtemp()
+        path = os.path.realpath(path)
+
+        try:
+            with support.check_warnings() as recorder:
+                with support.temp_dir(path, quiet=True) as temp_path:
+                    self.assertEqual(path, temp_path)
+                warnings = [str(w.message) for w in recorder.warnings]
+            # Make sure temp_dir did not delete the original directory.
+            self.assertTrue(os.path.isdir(path))
+        finally:
+            shutil.rmtree(path)
+
+        expected = ['tests may fail, unable to create temp dir: ' + path]
+        self.assertEqual(warnings, expected)
+
+    # Tests for change_cwd()
+
+    def test_change_cwd(self):
+        original_cwd = os.getcwd()
+
+        with support.temp_dir() as temp_path:
+            with support.change_cwd(temp_path) as new_cwd:
+                self.assertEqual(new_cwd, temp_path)
+                self.assertEqual(os.getcwd(), new_cwd)
+
+        self.assertEqual(os.getcwd(), original_cwd)
+
+    def test_change_cwd__non_existent_dir(self):
+        """Test passing a non-existent directory."""
+        original_cwd = os.getcwd()
+
+        def call_change_cwd(path):
+            with support.change_cwd(path) as new_cwd:
+                raise Exception("should not get here")
+
+        with support.temp_dir() as parent_dir:
+            non_existent_dir = os.path.join(parent_dir, 'does_not_exist')
+            self.assertRaises(FileNotFoundError, call_change_cwd,
+                              non_existent_dir)
+
+        self.assertEqual(os.getcwd(), original_cwd)
+
+    def test_change_cwd__non_existent_dir__quiet_true(self):
+        """Test passing a non-existent directory with quiet=True."""
+        original_cwd = os.getcwd()
+
+        with support.temp_dir() as parent_dir:
+            bad_dir = os.path.join(parent_dir, 'does_not_exist')
+            with support.check_warnings() as recorder:
+                with support.change_cwd(bad_dir, quiet=True) as new_cwd:
+                    self.assertEqual(new_cwd, original_cwd)
+                    self.assertEqual(os.getcwd(), new_cwd)
+                warnings = [str(w.message) for w in recorder.warnings]
+
+        expected = ['tests may fail, unable to change CWD to: ' + bad_dir]
+        self.assertEqual(warnings, expected)
+
+    # Tests for change_cwd()
+
+    def test_change_cwd__chdir_warning(self):
+        """Check the warning message when os.chdir() fails."""
+        path = TESTFN + '_does_not_exist'
+        with support.check_warnings() as recorder:
+            with support.change_cwd(path=path, quiet=True):
+                pass
+            messages = [str(w.message) for w in recorder.warnings]
+        self.assertEqual(messages, ['tests may fail, unable to change CWD to: ' + path])
+
+    # Tests for temp_cwd()
+
     def test_temp_cwd(self):
         here = os.getcwd()
         with support.temp_cwd(name=TESTFN):
@@ -95,14 +208,15 @@ class TestSupport(unittest.TestCase):
         self.assertFalse(os.path.exists(TESTFN))
         self.assertTrue(os.path.basename(os.getcwd()), here)
 
-    def test_temp_cwd__chdir_warning(self):
-        """Check the warning message when os.chdir() fails."""
-        path = TESTFN + '_does_not_exist'
-        with support.check_warnings() as recorder:
-            with support.temp_cwd(path=path, quiet=True):
-                pass
-            messages = [str(w.message) for w in recorder.warnings]
-        self.assertEqual(messages, ['tests may fail, unable to change the CWD to ' + path])
+
+    def test_temp_cwd__name_none(self):
+        """Test passing None to temp_cwd()."""
+        original_cwd = os.getcwd()
+        with support.temp_cwd(name=None) as new_cwd:
+            self.assertNotEqual(new_cwd, original_cwd)
+            self.assertTrue(os.path.isdir(new_cwd))
+            self.assertEqual(os.getcwd(), new_cwd)
+        self.assertEqual(os.getcwd(), original_cwd)
 
     def test_sortdict(self):
         self.assertEqual(support.sortdict({3:3, 2:2, 1:1}), "{1: 1, 2: 2, 3: 3}")