Do not attempt to launch Jedi language server in case when selected Python interpreter is invalid

src/client/languageServer/jediLSExtensionManager.ts

@@ -17,6 +17,7 @@ import {
 import { IEnvironmentVariablesProvider } from '../common/variables/types';
 import { IInterpreterService } from '../interpreter/contracts';
 import { IServiceContainer } from '../ioc/types';
+import { traceError } from '../logging';
 import { PythonEnvironment } from '../pythonEnvironments/info';
 import { LanguageServerCapabilities } from './languageServerCapabilities';
 import { ILanguageServerExtensionManager } from './types';
@@ -78,10 +79,13 @@ export class JediLSExtensionManager extends LanguageServerCapabilities
     }
 
     // eslint-disable-next-line class-methods-use-this
-    canStartLanguageServer(): boolean {
-        // Return true for now since it's shipped with the extension.
+    canStartLanguageServer(interpreter: PythonEnvironment | undefined): boolean {
+        if (!interpreter) {
+            traceError('Unable to start Jedi language server as a valid interpreter is not selected');
+            return false;
+        }
+        // Otherwise return true for now since it's shipped with the extension.
         // Update this when JediLSP is pulled in a separate extension.
-
         return true;
     }
 

src/client/languageServer/types.ts

@@ -31,7 +31,7 @@ export interface ILanguageServerCapabilities extends ILanguageServer {
 export interface ILanguageServerExtensionManager extends ILanguageServerCapabilities {
     startLanguageServer(resource: Resource, interpreter?: PythonEnvironment): Promise<void>;
     stopLanguageServer(): Promise<void>;
-    canStartLanguageServer(): boolean;
+    canStartLanguageServer(interpreter: PythonEnvironment | undefined): boolean;
     languageServerNotAvailable(): Promise<void>;
     dispose(): void;
 }

src/client/languageServer/watcher.ts

@@ -180,7 +180,7 @@ export class LanguageServerWatcher
         const languageServerExtensionManager = this.createLanguageServer(serverType);
         this.workspaceLanguageServers.set(key, languageServerExtensionManager);
 
-        if (languageServerExtensionManager.canStartLanguageServer()) {
+        if (languageServerExtensionManager.canStartLanguageServer(interpreter)) {
             // Start the language server.
             await languageServerExtensionManager.startLanguageServer(lsResource, interpreter);
 

src/test/languageServer/jediLSExtensionManager.unit.test.ts

@@ -9,6 +9,7 @@ import { IEnvironmentVariablesProvider } from '../../client/common/variables/typ
 import { IInterpreterService } from '../../client/interpreter/contracts';
 import { IServiceContainer } from '../../client/ioc/types';
 import { JediLSExtensionManager } from '../../client/languageServer/jediLSExtensionManager';
+import { PythonEnvironment } from '../../client/pythonEnvironments/info';
 
 suite('Language Server - Jedi LS extension manager', () => {
     let manager: JediLSExtensionManager;
@@ -37,9 +38,17 @@ suite('Language Server - Jedi LS extension manager', () => {
         assert.notStrictEqual(manager.serverProxy, undefined);
     });
 
-    test('canStartLanguageServer should return true', () => {
-        const result = manager.canStartLanguageServer();
+    test('canStartLanguageServer should return true if an interpreter is passed in', () => {
+        const result = manager.canStartLanguageServer(({
+            path: 'path/to/interpreter',
+        } as unknown) as PythonEnvironment);
 
         assert.strictEqual(result, true);
     });
+
+    test('canStartLanguageServer should return false otherwise', () => {
+        const result = manager.canStartLanguageServer(undefined);
+
+        assert.strictEqual(result, false);
+    });
 });