Add automated tests for interpreter resolution (#645)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: edvilme

src/common/python.ts

@@ -235,3 +235,8 @@ export function checkVersion(resolved: ResolvedEnvironment | undefined): boolean
     traceError(`Supported versions are ${PYTHON_VERSION} and above.`);
     return false;
 }
+
+export function resetCachedApis(): void {
+    _api = undefined;
+    _envsApi = undefined;
+}

src/test/ts_tests/tests/common/python.unit.test.ts

@@ -0,0 +1,161 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+import { assert } from 'chai';
+import * as sinon from 'sinon';
+import { EventEmitter, extensions, Uri } from 'vscode';
+import { PythonExtension } from '@vscode/python-extension';
+import { getInterpreterDetails, resetCachedApis } from '../../../../common/python';
+
+suite('Python Interpreter Resolution Tests', () => {
+    let getExtensionStub: sinon.SinonStub;
+    let pythonExtensionApiStub: sinon.SinonStub;
+
+    setup(() => {
+        resetCachedApis();
+        getExtensionStub = sinon.stub(extensions, 'getExtension');
+        pythonExtensionApiStub = sinon.stub(PythonExtension, 'api');
+    });
+
+    teardown(() => {
+        sinon.restore();
+    });
+
+    test('Finds interpreter using Python Environments extension', async () => {
+        const mockEnvsApi = {
+            getEnvironment: sinon.stub().resolves({
+                version: '3.12.0',
+                execInfo: {
+                    run: { executable: '/usr/bin/python3.12', args: [] },
+                },
+                envId: { id: 'test-env', managerId: 'test-manager' },
+                sysPrefix: '/usr',
+                name: 'test',
+                displayName: 'Python 3.12',
+                environmentPath: Uri.file('/usr/bin/python3.12'),
+            }),
+            resolveEnvironment: sinon.stub(),
+            onDidChangeEnvironment: new EventEmitter().event,
+        };
+
+        getExtensionStub.withArgs('ms-python.vscode-python-envs').returns({
+            isActive: true,
+            activate: sinon.stub().resolves(),
+            exports: mockEnvsApi,
+        });
+
+        const result = await getInterpreterDetails(Uri.file('/test/workspace'));
+
+        assert.isDefined(result.path);
+        assert.strictEqual(result.path![0], '/usr/bin/python3.12');
+        assert.isTrue(mockEnvsApi.getEnvironment.calledOnce);
+        // Legacy API should not be called
+        assert.isTrue(pythonExtensionApiStub.notCalled);
+    });
+
+    test('Finds interpreter using legacy ms-python.python extension', async () => {
+        // Envs extension not installed
+        getExtensionStub.withArgs('ms-python.vscode-python-envs').returns(undefined);
+
+        const interpreterUri = Uri.file('/usr/bin/python3.10');
+        const mockLegacyApi = {
+            environments: {
+                getActiveEnvironmentPath: sinon.stub().returns('/usr/bin/python3.10'),
+                resolveEnvironment: sinon.stub().resolves({
+                    executable: {
+                        uri: interpreterUri,
+                        bitness: '64-bit',
+                        sysPrefix: '/usr',
+                    },
+                    version: {
+                        major: 3,
+                        minor: 10,
+                        micro: 0,
+                        release: { level: 'final', serial: 0 },
+                        sysVersion: '3.10.0',
+                    },
+                }),
+                onDidChangeActiveEnvironmentPath: new EventEmitter().event,
+            },
+            debug: {
+                getDebuggerPackagePath: sinon.stub(),
+            },
+        };
+
+        pythonExtensionApiStub.resolves(mockLegacyApi);
+
+        const result = await getInterpreterDetails(Uri.file('/test/workspace'));
+
+        assert.isDefined(result.path);
+        assert.strictEqual(result.path![0], interpreterUri.fsPath);
+        assert.isTrue(mockLegacyApi.environments.resolveEnvironment.calledOnce);
+    });
+
+    test('Rejects unsupported Python version from Environments extension', async () => {
+        const mockEnvsApi = {
+            getEnvironment: sinon.stub().resolves({
+                version: '3.8.0',
+                execInfo: {
+                    run: { executable: '/usr/bin/python3.8', args: [] },
+                },
+                envId: { id: 'old-env', managerId: 'test-manager' },
+                sysPrefix: '/usr',
+                name: 'old-python',
+                displayName: 'Python 3.8',
+                environmentPath: Uri.file('/usr/bin/python3.8'),
+            }),
+            resolveEnvironment: sinon.stub(),
+            onDidChangeEnvironment: new EventEmitter().event,
+        };
+
+        getExtensionStub.withArgs('ms-python.vscode-python-envs').returns({
+            isActive: true,
+            activate: sinon.stub().resolves(),
+            exports: mockEnvsApi,
+        });
+
+        const result = await getInterpreterDetails(Uri.file('/test/workspace'));
+
+        assert.isUndefined(result.path);
+        assert.isTrue(mockEnvsApi.getEnvironment.calledOnce);
+        // Should not fall through to legacy when version is explicitly unsupported
+        assert.isTrue(pythonExtensionApiStub.notCalled);
+    });
+
+    test('Rejects unsupported Python version from legacy extension', async () => {
+        // Envs extension not installed
+        getExtensionStub.withArgs('ms-python.vscode-python-envs').returns(undefined);
+
+        const interpreterUri = Uri.file('/usr/bin/python3.8');
+        const mockLegacyApi = {
+            environments: {
+                getActiveEnvironmentPath: sinon.stub().returns('/usr/bin/python3.8'),
+                resolveEnvironment: sinon.stub().resolves({
+                    executable: {
+                        uri: interpreterUri,
+                        bitness: '64-bit',
+                        sysPrefix: '/usr',
+                    },
+                    version: {
+                        major: 3,
+                        minor: 8,
+                        micro: 0,
+                        release: { level: 'final', serial: 0 },
+                        sysVersion: '3.8.0',
+                    },
+                }),
+                onDidChangeActiveEnvironmentPath: new EventEmitter().event,
+            },
+            debug: {
+                getDebuggerPackagePath: sinon.stub(),
+            },
+        };
+
+        pythonExtensionApiStub.resolves(mockLegacyApi);
+
+        const result = await getInterpreterDetails(Uri.file('/test/workspace'));
+
+        assert.isUndefined(result.path);
+        assert.isTrue(mockLegacyApi.environments.resolveEnvironment.calledOnce);
+    });
+});