Use CLI flag --install-extensions instead of config property

The config property may be less reliable than the CLI flag for
installing extensions before running tests.

Author: eleanorjboyd

.vscode-test.mjs

@@ -41,9 +41,9 @@ export default defineConfig([
             `--user-data-dir=${userDataDir}`,
             '--disable-workspace-trust',
         ],
-        // Install ms-python.python for the native Python tools (pet binary).
-        // We use inspect() for useEnvironmentsExtension check, so defaults are ignored.
-        installExtensions: ['ms-python.python'],
+        // ms-python.python is installed via CLI flag (--install-extensions) for
+        // the native Python tools (pet binary). We use inspect() for
+        // useEnvironmentsExtension check, so Python extension's default is ignored.
     },
     {
         label: 'integrationTests',
@@ -60,9 +60,9 @@ export default defineConfig([
             `--user-data-dir=${userDataDir}`,
             '--disable-workspace-trust',
         ],
-        // Install ms-python.python for the native Python tools (pet binary).
-        // We use inspect() for useEnvironmentsExtension check, so defaults are ignored.
-        installExtensions: ['ms-python.python'],
+        // ms-python.python is installed via CLI flag (--install-extensions) for
+        // the native Python tools (pet binary). We use inspect() for
+        // useEnvironmentsExtension check, so Python extension's default is ignored.
     },
     {
         label: 'extensionTests',

package.json

@@ -683,8 +683,8 @@
         "lint": "eslint --config=eslint.config.mjs src",
         "unittest": "mocha --config=./build/.mocha.unittests.json",
         "smoke-test": "vscode-test --label smokeTests",
-        "e2e-test": "vscode-test --label e2eTests",
-        "integration-test": "vscode-test --label integrationTests",
+        "e2e-test": "vscode-test --label e2eTests --install-extensions ms-python.python",
+        "integration-test": "vscode-test --label integrationTests --install-extensions ms-python.python",
         "vsce-package": "vsce package -o ms-python-envs-insiders.vsix"
     },
     "devDependencies": {