test: replace mocha with vitest

.gitignore

@@ -88,5 +88,7 @@ lib/common/test-reports.xml
 !lib/common/scripts/**
 config/test-deps-versions-generated.json
 !scripts/*.js
+!dev/*.js
+
 # build output
 /dist

dev/tsc-to-vitest-watch.js

@@ -0,0 +1,37 @@
+// Run "tsc" in watch mode alongside vitest. Vitest runs the compiled output,
+// so on its own it never notices a .ts edit - tsc has to re-emit first, and
+// vitest picks the change up from there.
+
+const { spawn } = require("child_process");
+
+// shell: true so the node_modules/.bin shims resolve on Windows as well
+const spawnOptions = { stdio: "inherit", shell: true };
+
+const children = [
+	// --preserveWatchOutput keeps tsc from clearing the screen and wiping the
+	// test results out from under you on every recompile
+	spawn("tsc", ["--watch", "--preserveWatchOutput"], spawnOptions),
+	// --watch explicitly: vitest only infers watch mode when stdout is a TTY,
+	// and would otherwise run once and exit, taking tsc down with it
+	spawn("vitest", ["--watch"], spawnOptions),
+];
+
+let shuttingDown = false;
+
+function shutdown() {
+	if (shuttingDown) {
+		return;
+	}
+	shuttingDown = true;
+	for (const child of children) {
+		child.kill("SIGINT");
+	}
+}
+
+process.on("SIGINT", shutdown);
+process.on("SIGTERM", shutdown);
+
+for (const child of children) {
+	// if either side dies, don't leave the other running in the background
+	child.on("exit", shutdown);
+}

lib/common/test/unit-tests/analytics-service.ts

@@ -128,7 +128,7 @@ describe("analytics-service", () => {
 		service = null;
 	});
 
-	after(() => {
+	afterAll(() => {
 		setIsInteractive(null);
 	});
 
@@ -147,8 +147,8 @@ describe("analytics-service", () => {
 		});
 
 		it("returns false when analytics status is disabled", async () => {
-			baseTestScenario.exceptionsTracking = baseTestScenario.featureTracking =
-				false;
+			baseTestScenario.exceptionsTracking =
+				baseTestScenario.featureTracking = false;
 			const testInjector = createTestInjector(baseTestScenario);
 			service = testInjector.resolve<IAnalyticsService>("analyticsService");
 			const staticConfig: Config.IStaticConfig =
@@ -377,8 +377,8 @@ describe("analytics-service", () => {
 		});
 
 		it("does nothing when exception and feature tracking are already set", async () => {
-			baseTestScenario.featureTracking = baseTestScenario.exceptionsTracking =
-				true;
+			baseTestScenario.featureTracking =
+				baseTestScenario.exceptionsTracking = true;
 			const testInjector = createTestInjector(baseTestScenario);
 			service = testInjector.resolve<IAnalyticsService>("analyticsService");
 			await service.checkConsent();