fix(tests): skip symlink tests when symlink creation is unprivileged

tests/functional/test_actions.py

@@ -1,13 +1,17 @@
 import os
 from pathlib import Path
 import tempfile
+import unittest
 from unittest import TestCase
 from parameterized import parameterized
 
 
 from aws_lambda_builders.actions import CopyDependenciesAction, LinkSinglePathAction, MoveDependenciesAction
 from aws_lambda_builders.utils import copytree
-from tests.testing_utils import read_link_without_junction_prefix
+from tests.testing_utils import read_link_without_junction_prefix, symlinks_supported
+
+SYMLINKS_SUPPORTED = symlinks_supported()
+SYMLINKS_UNSUPPORTED_REASON = "Creating symlinks requires Administrator privileges or Developer Mode on this platform"
 
 
 class TestCopyDependenciesAction(TestCase):
@@ -32,6 +36,7 @@ def test_copy_dependencies_action(self, source_folder):
 
             self.assertEqual(set(os.listdir(test_folder)), set(os.listdir(target)))
 
+    @unittest.skipUnless(SYMLINKS_SUPPORTED, SYMLINKS_UNSUPPORTED_REASON)
     def test_must_maintain_symlinks_if_enabled(self):
         with tempfile.TemporaryDirectory() as tmpdir:
             source_dir = os.path.join(tmpdir, "source")
@@ -56,6 +61,7 @@ def test_must_maintain_symlinks_if_enabled(self):
             destination_node_modules_target = read_link_without_junction_prefix(destination_node_modules)
             self.assertEqual(destination_node_modules_target, source_node_modules)
 
+    @unittest.skipUnless(SYMLINKS_SUPPORTED, SYMLINKS_UNSUPPORTED_REASON)
     def test_must_not_maintain_symlinks_by_default(self):
         with tempfile.TemporaryDirectory() as tmpdir:
             source_dir = os.path.join(tmpdir, "source")
@@ -78,6 +84,7 @@ def test_must_not_maintain_symlinks_by_default(self):
 
 
 class TestLinkSinglePathAction(TestCase):
+    @unittest.skipUnless(SYMLINKS_SUPPORTED, SYMLINKS_UNSUPPORTED_REASON)
     def test_link_directory(self):
         with tempfile.TemporaryDirectory() as tmpdir:
             source_dir = os.path.join(tmpdir, "source")

tests/functional/test_utils.py

@@ -2,12 +2,16 @@
 import tempfile
 import shutil
 import platform
+import unittest
 from tarfile import ExtractError
 
 from unittest import TestCase
 
 from aws_lambda_builders.utils import copytree, get_goarch, extract_tarfile
-from tests.testing_utils import read_link_without_junction_prefix
+from tests.testing_utils import read_link_without_junction_prefix, symlinks_supported
+
+SYMLINKS_SUPPORTED = symlinks_supported()
+SYMLINKS_UNSUPPORTED_REASON = "Creating symlinks requires Administrator privileges or Developer Mode on this platform"
 
 
 class TestCopyTree(TestCase):
@@ -65,6 +69,7 @@ def test_must_return_valid_go_architecture(self):
         self.assertEqual(get_goarch("x86_64"), "amd64")
         self.assertEqual(get_goarch(""), "amd64")
 
+    @unittest.skipUnless(SYMLINKS_SUPPORTED, SYMLINKS_UNSUPPORTED_REASON)
     def test_must_maintain_symlinks_if_enabled(self):
         # set up symlinked file and directory
         source_target_file_path = file(self.source, "targetfile.txt")
@@ -92,6 +97,7 @@ def test_must_maintain_symlinks_if_enabled(self):
         dest_symlink_dir_target = read_link_without_junction_prefix(dest_symlink_file_path)
         self.assertEqual(dest_symlink_dir_target, source_target_file_path)
 
+    @unittest.skipUnless(SYMLINKS_SUPPORTED, SYMLINKS_UNSUPPORTED_REASON)
     def test_must_not_maintain_symlinks_by_default(self):
         # set up symlinked file and directory
         source_target_file_path = file(self.source, "targetfile.txt")

tests/testing_utils.py

@@ -1,4 +1,34 @@
 import os
+import sys
+import tempfile
+
+
+def symlinks_supported() -> bool:
+    """
+    Returns True if the current platform and user are able to create symlinks.
+
+    On Windows, os.symlink() requires either Administrator privileges or Developer
+    Mode to be enabled (Windows 10+). Without either, it raises
+    ``OSError: [WinError 1314] A required privilege is not held by the client``.
+    Developer Mode is off by default, so this is the common case for a Windows
+    contributor running the test suite locally.
+
+    Returns
+    -------
+    bool
+        True if os.symlink() is expected to succeed on this machine.
+    """
+    if sys.platform != "win32":
+        return True
+    with tempfile.TemporaryDirectory() as tmpdir:
+        target = os.path.join(tmpdir, "target")
+        link = os.path.join(tmpdir, "link")
+        open(target, "w").close()
+        try:
+            os.symlink(target, link)
+        except OSError:
+            return False
+    return True
 
 
 def read_link_without_junction_prefix(path: str) -> str: