Add a noop envs cache implementation.

Author: ericsnowcurrently

src/client/pythonEnvironments/base/cache.ts

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+import { PythonEnvInfo } from './info';
+import { IPythonEnvsCache } from './locators/composite/cachingLocator';
+
+/**
+ * A rudimentary empty cache.
+ */
+export class EmptyCache implements IPythonEnvsCache {
+    public async initialize(): Promise<void> {
+        // Do nothing!
+    }
+
+    public getAllEnvs(): PythonEnvInfo[] | undefined {
+        return undefined;
+    }
+
+    public matchEnv(_env: Partial<PythonEnvInfo>): PythonEnvInfo[] {
+        return [];
+    }
+
+    public setAllEnvs(_envs: PythonEnvInfo[]): void {
+        // Do nothing!
+    }
+
+    public async flush(): Promise<void> {
+        // Do nothing!
+    }
+}