Listen for extensions being installed/unistalled to avoid race condition when both this extension and ms-python.python are installed during startup (#1839)

Author: mattseddon

extension/src/config.ts

@@ -1,10 +1,12 @@
+import { Disposable } from '@hediet/std/disposable'
 import { EventEmitter, Event, workspace } from 'vscode'
 import {
   getOnDidChangePythonExecutionDetails,
   getPythonBinPath
 } from './extensions/python'
 import { ConfigKey, getConfigValue } from './vscode/config'
 import { DeferredDisposable } from './class/deferred'
+import { getOnDidChangeExtensions } from './vscode/extensions'
 
 export class Config extends DeferredDisposable {
   public readonly onDidChangeExecutionDetails: Event<void>
@@ -15,15 +17,20 @@ export class Config extends DeferredDisposable {
 
   private readonly executionDetailsChanged: EventEmitter<void>
 
-  constructor() {
+  private pythonExecutionDetailsListener?: Disposable
+  private readonly onDidChangeExtensionsEvent: Event<void>
+
+  constructor(onDidChangeExtensionsEvent = getOnDidChangeExtensions()) {
     super()
 
     this.executionDetailsChanged = this.dispose.track(new EventEmitter())
     this.onDidChangeExecutionDetails = this.executionDetailsChanged.event
+    this.onDidChangeExtensionsEvent = onDidChangeExtensionsEvent
 
     this.setPythonBinPath()
 
     this.onDidChangePythonExecutionDetails()
+    this.onDidChangeExtensions()
 
     this.onDidConfigurationChange()
   }
@@ -46,15 +53,25 @@ export class Config extends DeferredDisposable {
   }
 
   private async onDidChangePythonExecutionDetails() {
+    this.pythonExecutionDetailsListener?.dispose()
     const onDidChangePythonExecutionDetails =
       await getOnDidChangePythonExecutionDetails()
-    this.dispose.track(
+    this.pythonExecutionDetailsListener = this.dispose.track(
       onDidChangePythonExecutionDetails?.(() => {
         this.setPythonAndNotifyIfChanged()
       })
     )
   }
 
+  private onDidChangeExtensions() {
+    this.dispose.track(
+      this.onDidChangeExtensionsEvent(() => {
+        this.onDidChangePythonExecutionDetails()
+        this.setPythonAndNotifyIfChanged()
+      })
+    )
+  }
+
   private onDidConfigurationChange() {
     this.dispose.track(
       workspace.onDidChangeConfiguration(e => {

extension/src/test/suite/config.test.ts

@@ -0,0 +1,51 @@
+import { join } from 'path'
+import { afterEach, beforeEach, describe, it, suite } from 'mocha'
+import { expect } from 'chai'
+import { stub, restore } from 'sinon'
+import { EventEmitter } from 'vscode'
+import { Disposable } from '../../extension'
+import { Config } from '../../config'
+import * as Extensions from '../../vscode/extensions'
+import * as Python from '../../extensions/python'
+
+suite('Config Test Suite', () => {
+  const disposable = Disposable.fn()
+
+  beforeEach(() => {
+    restore()
+  })
+
+  afterEach(() => {
+    disposable.dispose()
+  })
+
+  describe('Config', () => {
+    it('should re-fetch the python extension API (and execution details) if any extensions are enabled/disabled or installed/uninstalled', async () => {
+      const mockGetExtensionAPI = stub(Extensions, 'getExtensionAPI').resolves(
+        undefined
+      )
+
+      const extensionsChanged = disposable.track(new EventEmitter<void>())
+
+      const config = disposable.track(new Config(extensionsChanged.event))
+      expect(mockGetExtensionAPI).to.be.calledTwice
+      expect(config.pythonBinPath).to.be.undefined
+
+      const pythonBinPath = join('some', 'magic', 'python', 'path')
+
+      const executionDetailsUpdated = new Promise(resolve =>
+        disposable.track(
+          config.onDidChangeExecutionDetails(() => {
+            resolve(undefined)
+          })
+        )
+      )
+
+      stub(Python, 'getPythonBinPath').resolves(pythonBinPath)
+      extensionsChanged.fire()
+
+      await executionDetailsUpdated
+      expect(config.pythonBinPath).to.equal(pythonBinPath)
+    })
+  })
+})

extension/src/vscode/extensions.ts

@@ -41,3 +41,5 @@ export const isInstalled = (id: string): boolean =>
 
 export const showExtension = (id: string) =>
   commands.executeCommand('workbench.extensions.search', `@id:${id}`)
+
+export const getOnDidChangeExtensions = () => extensions.onDidChange