test: add integration testing

.vscode-test.js

@@ -0,0 +1,11 @@
+const { defineConfig } = require('@vscode/test-cli')
+
+module.exports = defineConfig({
+  files: ['test/**/*.test.js'],
+  workspaceFolder: 'test/testWorkspace',
+
+  mocha: {
+    // Downloading compiler takes a long time
+    timeout: 60000,
+  },
+})

client/src/services/state.ts

@@ -27,11 +27,18 @@ enum StateKeys {
   installedFlixVersion = 'installedFlixVersion',
 }
 
-export function getInstalledFlixVersion(): FlixRelease {
+/**
+ * Get the installed Flix release if one exists.
+ *
+ * In the test environment this will always return `undefined` when called the first time in a test run,
+ * even if an installed Flix compiler exists.
+ * This happens because the extension's 'Memento' is reset between each run.
+ */
+export function getInstalledFlixVersion(): FlixRelease | undefined {
   return globalState?.get(StateKeys.installedFlixVersion)
 }
 
-export async function setInstalledFlixVersion(value) {
+export async function setInstalledFlixVersion(value: FlixRelease) {
   await globalState?.update(StateKeys.installedFlixVersion, value)
   return openFlixReleaseOverview(value)
 }

client/src/util/ensureFlixExists.ts

@@ -40,8 +40,8 @@ export default async function ensureFlixExists({ globalStoragePath, workspaceFol
     }
     // 2. If `flix.jar` exists in `globalStoragePath`, use that
     const filename = path.join(globalStoragePath, FLIX_JAR)
-    if (fs.existsSync(filename)) {
-      const installedFlixRelease: FlixRelease = getInstalledFlixVersion()
+    const installedFlixRelease = getInstalledFlixVersion()
+    if (fs.existsSync(filename) && installedFlixRelease) {
       const thirtyMinutesInMilliseconds = 1000 * 60 * 30
 
       // skip if we checked under 30 minutes ago