Issue #15168: Move importlb.test to test.test_importlib.

This should make the Linux distros happy as it is now easier to leave
importlib's tests out of their base Python distribution.

Lib/test/test_importlib/source/util.py

@@ -0,0 +1,97 @@
+from .. import util
+import contextlib
+import errno
+import functools
+import imp
+import os
+import os.path
+import sys
+import tempfile
+from test import support
+
+
+def writes_bytecode_files(fxn):
+    """Decorator to protect sys.dont_write_bytecode from mutation and to skip
+    tests that require it to be set to False."""
+    if sys.dont_write_bytecode:
+        return lambda *args, **kwargs: None
+    @functools.wraps(fxn)
+    def wrapper(*args, **kwargs):
+        original = sys.dont_write_bytecode
+        sys.dont_write_bytecode = False
+        try:
+            to_return = fxn(*args, **kwargs)
+        finally:
+            sys.dont_write_bytecode = original
+        return to_return
+    return wrapper
+
+
+def ensure_bytecode_path(bytecode_path):
+    """Ensure that the __pycache__ directory for PEP 3147 pyc file exists.
+
+    :param bytecode_path: File system path to PEP 3147 pyc file.
+    """
+    try:
+        os.mkdir(os.path.dirname(bytecode_path))
+    except OSError as error:
+        if error.errno != errno.EEXIST:
+            raise
+
+
+@contextlib.contextmanager
+def create_modules(*names):
+    """Temporarily create each named module with an attribute (named 'attr')
+    that contains the name passed into the context manager that caused the
+    creation of the module.
+
+    All files are created in a temporary directory returned by
+    tempfile.mkdtemp(). This directory is inserted at the beginning of
+    sys.path. When the context manager exits all created files (source and
+    bytecode) are explicitly deleted.
+
+    No magic is performed when creating packages! This means that if you create
+    a module within a package you must also create the package's __init__ as
+    well.
+
+    """
+    source = 'attr = {0!r}'
+    created_paths = []
+    mapping = {}
+    state_manager = None
+    uncache_manager = None
+    try:
+        temp_dir = tempfile.mkdtemp()
+        mapping['.root'] = temp_dir
+        import_names = set()
+        for name in names:
+            if not name.endswith('__init__'):
+                import_name = name
+            else:
+                import_name = name[:-len('.__init__')]
+            import_names.add(import_name)
+            if import_name in sys.modules:
+                del sys.modules[import_name]
+            name_parts = name.split('.')
+            file_path = temp_dir
+            for directory in name_parts[:-1]:
+                file_path = os.path.join(file_path, directory)
+                if not os.path.exists(file_path):
+                    os.mkdir(file_path)
+                    created_paths.append(file_path)
+            file_path = os.path.join(file_path, name_parts[-1] + '.py')
+            with open(file_path, 'w') as file:
+                file.write(source.format(name))
+            created_paths.append(file_path)
+            mapping[name] = file_path
+        uncache_manager = util.uncache(*import_names)
+        uncache_manager.__enter__()
+        state_manager = util.import_state(path=[temp_dir])
+        state_manager.__enter__()
+        yield mapping
+    finally:
+        if state_manager is not None:
+            state_manager.__exit__(None, None, None)
+        if uncache_manager is not None:
+            uncache_manager.__exit__(None, None, None)
+        support.rmtree(temp_dir)