[PATCH] tests/arg_parser: add test for lazy loading of bb.ui modules

[PATCH] tests/arg_parser: add test for lazy loading of bb.ui modules

[Chris Laplante]

Ensures bb.ui modules are loaded lazily during construction
of the 'bitbake' argument parser.

Signed-off-by: Chris Laplante <chris.laplante@agilent.com>
---
 bin/bitbake-selftest       |  3 ++-
 lib/bb/main.py             |  5 ++++-
 lib/bb/tests/arg_parser.py | 30 ++++++++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 lib/bb/tests/arg_parser.py

diff --git a/bin/bitbake-selftest b/bin/bitbake-selftest
index 6c073741..cc794bd6 100755
--- a/bin/bitbake-selftest
+++ b/bin/bitbake-selftest
@@ -17,7 +17,8 @@ try:
 except RuntimeError as exc:
     sys.exit(str(exc))
 
-tests = ["bb.tests.codeparser",
+tests = ["bb.tests.arg_parser",
+         "bb.tests.codeparser",
          "bb.tests.color",
          "bb.tests.cooker",
          "bb.tests.cow",
diff --git a/lib/bb/main.py b/lib/bb/main.py
index 2fb81a23..16ff6e59 100755
--- a/lib/bb/main.py
+++ b/lib/bb/main.py
@@ -98,12 +98,15 @@ class LazyUiChoices:
     """
     def __init__(self):
         # map module name => imported module
-        self._modules = {}
+        self._modules = None
 
     def _lazy_load_modules(self):
         if not self._modules:
             self._modules = {module.__name__.split(".")[-1]: module for module in load_extension_modules(bb.ui, "main")}
 
+    @property
+    def has_loaded_modules(self): return self._modules is not None
+
     def __iter__(self):
         self._lazy_load_modules()
         yield from self._modules.keys()
diff --git a/lib/bb/tests/arg_parser.py b/lib/bb/tests/arg_parser.py
new file mode 100644
index 00000000..0c8941f8
--- /dev/null
+++ b/lib/bb/tests/arg_parser.py
@@ -0,0 +1,30 @@
+#
+# BitBake Test for the main 'bitbake' argument parser
+#
+# Copyright (C) 2020  Agilent Technologies, Inc.
+# Author: Chris Laplante <chris.laplante@agilent.com>
+#
+# SPDX-License-Identifier: MIT
+#
+
+import unittest
+
+from bb.main import create_bitbake_parser, LazyUiChoices
+
+
+class ArgParserTests(unittest.TestCase):
+    def setUp(self):
+        self._parser = create_bitbake_parser()
+
+    def test_lazy_module_loading(self):
+        # This test ensures that the bb.ui modules weren't loaded immediately upon creation of the arg parser
+
+        # Find the UI action
+        ui_actions = [action for action in self._parser._actions if action.dest == "ui"]
+        if len(ui_actions) > 1:
+            self.fail("Found more than one 'ui' action in the argument parser?")
+        self.assertEqual(len(ui_actions), 1, "Didn't find the 'ui' action in the argument parser?")
+
+        ui_action = ui_actions[0]
+        self.assertIs(type(ui_action.type), LazyUiChoices, "'ui' action has wrong type")
+        self.assertFalse(ui_action.type.has_loaded_modules, "Creation of the arg parser loaded the bb.ui modules")
-- 
2.17.1