Python tests can now be debugged by running them as embedded tests within NUnit

tminka · tminka · commit 085f1e66f6d7 · 2020-12-31T14:13:35.000Z
diff --git a/src/embed_tests/TestPythonTests.cs b/src/embed_tests/TestPythonTests.cs
@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+
+using NUnit.Framework;
+
+using Python.Runtime;
+
+namespace Python.EmbeddingTest
+{
+    public class TestPythonTests
+    {
+        [OneTimeSetUp]
+        public void SetUp()
+        {
+            PythonEngine.Initialize();
+        }
+
+        [OneTimeTearDown]
+        public void Dispose()
+        {
+            PythonEngine.Shutdown();
+        }
+
+        /// <summary>
+        /// Selects the Python tests to be run as embedded tests.
+        /// </summary>
+        /// <returns></returns>
+        static IEnumerable<string[]> PythonTestCases()
+        {
+            // Add the test that you want to debug here.
+            yield return new[] { "test_enum", "test_enum_standard_attrs" };
+            yield return new[] { "test_generic", "test_missing_generic_type" };
+        }
+
+        /// <summary>
+        /// Runs a test in src/tests/*.py as an embedded test.  This facilitates debugging.
+        /// </summary>
+        /// <param name="testFile">The file name without extension</param>
+        /// <param name="testName">The name of the test method</param>
+        [TestCaseSource(nameof(PythonTestCases))]
+        public void TestPythonTest(string testFile, string testName)
+        {
+            // Find the tests directory
+            string folder = typeof(TestPythonTests).Assembly.Location;
+            while (Path.GetFileName(folder) != "src")
+            {
+                folder = Path.GetDirectoryName(folder);
+            }
+            folder = Path.Combine(folder, "tests");
+            string path = Path.Combine(folder, testFile + ".py");
+            if (!File.Exists(path)) throw new FileNotFoundException("Cannot find test file", path);
+
+            // We could use 'import' below, but importlib gives more helpful error messages than 'import'
+            // https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
+            // Because the Python tests sometimes have relative imports, the module name must be inside the tests package
+            PythonEngine.Exec($@"
+import sys
+import os
+sys.path.append(os.path.dirname(r'{folder}'))
+sys.path.append(os.path.join(r'{folder}', 'fixtures'))
+import clr
+clr.AddReference('Python.Test')
+import tests
+module_name = 'tests.{testFile}'
+file_path = r'{path}'
+import importlib.util
+spec = importlib.util.spec_from_file_location(module_name, file_path)
+module = importlib.util.module_from_spec(spec)
+sys.modules[module_name] = module
+spec.loader.exec_module(module)
+module.{testName}()
+");
+        }
+    }
+}
