refactor: use sync.WaitGroup.Go in tests (#26671)

Migrate `wg.Add(1); go func() { defer wg.Done(); ... }()` to
`wg.Go(func() { ... })` in tests.

Where the prior pattern passed the loop variable explicitly via a
closure parameter (`go func(id int) { ... }(i)`), drop the parameter and
reference the loop variable directly. Per-iteration loop variables since
Go 1.22 make this safe.

coderd/boundaryusage/tracker_test.go

@@ -124,15 +124,13 @@ func TestTracker_Track_Concurrent(t *testing.T) {
 
 	var wg sync.WaitGroup
 	for i := 0; i < numGoroutines; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			workspaceID := uuid.New()
 			ownerID := uuid.New()
 			for j := 0; j < requestsPerGoroutine; j++ {
 				tracker.Track(workspaceID, ownerID, 1, 1)
 			}
-		}()
+		})
 	}
 	wg.Wait()
 
@@ -507,22 +505,18 @@ func TestTracker_ConcurrentFlushAndTrack(t *testing.T) {
 	var wg sync.WaitGroup
 
 	// Goroutine 1: Continuously track.
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+	wg.Go(func() {
 		for i := 0; i < numOperations; i++ {
 			tracker.Track(uuid.New(), uuid.New(), 1, 1)
 		}
-	}()
+	})
 
 	// Goroutine 2: Continuously flush.
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+	wg.Go(func() {
 		for i := 0; i < numOperations; i++ {
 			_ = tracker.FlushToDB(ctx, db, replicaID)
 		}
-	}()
+	})
 
 	wg.Wait()
 

coderd/httpmw/ratelimit_test.go

@@ -286,9 +286,7 @@ func TestConcurrencyLimit(t *testing.T) {
 
 		var wg sync.WaitGroup
 		for i := 0; i < maxConcurrency; i++ {
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				req, err := http.NewRequestWithContext(ctx, http.MethodGet, server.URL+"/", nil)
 				if err != nil {
 					results <- result{err: err}
@@ -301,7 +299,7 @@ func TestConcurrencyLimit(t *testing.T) {
 				}
 				defer resp.Body.Close()
 				results <- result{statusCode: resp.StatusCode}
-			}()
+			})
 		}
 
 		// Wait for all requests to enter the handler with a timeout.

coderd/notifications/dispatch/smtp_test.go

@@ -445,11 +445,9 @@ func TestSMTP(t *testing.T) {
 
 			// Start mock SMTP server in the background.
 			var wg sync.WaitGroup
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				assert.NoError(t, srv.Serve(listen))
-			}()
+			})
 
 			// Wait for the server to become pingable.
 			require.Eventually(t, func() bool {
@@ -590,11 +588,9 @@ func TestSMTPEnvelopeAndHeaders(t *testing.T) {
 			handler := dispatch.NewSMTPHandler(cfg, logger.Named("smtp"))
 
 			var wg sync.WaitGroup
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
+			wg.Go(func() {
 				assert.NoError(t, srv.Serve(listen))
-			}()
+			})
 
 			require.Eventually(t, func() bool {
 				cl, err := smtptest.PingClient(listen, false, false)

coderd/notifications/notifications_test.go

@@ -1541,11 +1541,9 @@ func TestNotificationTemplates_Golden(t *testing.T) {
 
 				// Start mock SMTP server in the background.
 				var wg sync.WaitGroup
-				wg.Add(1)
-				go func() {
-					defer wg.Done()
+				wg.Go(func() {
 					assert.NoError(t, srv.Serve(listen))
-				}()
+				})
 
 				// Wait for the server to become pingable.
 				require.Eventually(t, func() bool {

coderd/oauth2_security_test.go

@@ -421,13 +421,10 @@ func TestOAuth2ConcurrentSecurityOperations(t *testing.T) {
 
 		// Launch concurrent attempts to access the client configuration
 		for i := 0; i < numGoroutines; i++ {
-			wg.Add(1)
-			go func(index int) {
-				defer wg.Done()
-
+			wg.Go(func() {
 				_, err := client.GetOAuth2ClientConfiguration(ctx, regResp.ClientID, regResp.RegistrationAccessToken)
-				errors[index] = err
-			}(i)
+				errors[i] = err
+			})
 		}
 
 		wg.Wait()
@@ -448,23 +445,20 @@ func TestOAuth2ConcurrentSecurityOperations(t *testing.T) {
 
 		// Launch concurrent attempts with invalid tokens
 		for i := 0; i < numGoroutines; i++ {
-			wg.Add(1)
-			go func(index int) {
-				defer wg.Done()
-
-				_, err := client.GetOAuth2ClientConfiguration(ctx, regResp.ClientID, fmt.Sprintf("invalid-token-%d", index))
+			wg.Go(func() {
+				_, err := client.GetOAuth2ClientConfiguration(ctx, regResp.ClientID, fmt.Sprintf("invalid-token-%d", i))
 				if err == nil {
-					t.Errorf("Expected error for goroutine %d", index)
+					t.Errorf("Expected error for goroutine %d", i)
 					return
 				}
 
 				var httpErr *codersdk.Error
 				if !errors.As(err, &httpErr) {
-					t.Errorf("Expected codersdk.Error for goroutine %d", index)
+					t.Errorf("Expected codersdk.Error for goroutine %d", i)
 					return
 				}
-				statusCodes[index] = httpErr.StatusCode()
-			}(i)
+				statusCodes[i] = httpErr.StatusCode()
+			})
 		}
 
 		wg.Wait()
@@ -494,13 +488,10 @@ func TestOAuth2ConcurrentSecurityOperations(t *testing.T) {
 
 		// Launch concurrent deletion attempts
 		for i := 0; i < numGoroutines; i++ {
-			wg.Add(1)
-			go func(index int) {
-				defer wg.Done()
-
+			wg.Go(func() {
 				err := client.DeleteOAuth2ClientConfiguration(ctx, deleteRegResp.ClientID, deleteRegResp.RegistrationAccessToken)
-				deleteResults[index] = err
-			}(i)
+				deleteResults[i] = err
+			})
 		}
 
 		wg.Wait()

coderd/workspacestats/tracker_test.go

@@ -87,11 +87,9 @@ func TestTracker(t *testing.T) {
 	var wg sync.WaitGroup
 	count = 0
 	for i := 0; i < len(ids); i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			tickCh <- now
-		}()
+		})
 		wut.Add(ids[i])
 	}
 
@@ -173,18 +171,14 @@ func TestTracker_MultipleInstances(t *testing.T) {
 	nowB := now.Add(2 * time.Minute)
 	var wg sync.WaitGroup
 	var flushedA, flushedB int
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+	wg.Go(func() {
 		wuTickA <- nowA
 		flushedA = <-wuFlushA
-	}()
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+	})
+	wg.Go(func() {
 		wuTickB <- nowB
 		flushedB = <-wuFlushB
-	}()
+	})
 	wg.Wait()
 
 	// We expect 5 flushed IDs each

coderd/x/chatd/configcache_internal_test.go

@@ -416,12 +416,10 @@ func TestConfigCache_Singleflight(t *testing.T) {
 	var wg sync.WaitGroup
 	start := make(chan struct{})
 	for i := 0; i < callers; i++ {
-		wg.Add(1)
-		go func(i int) {
-			defer wg.Done()
+		wg.Go(func() {
 			<-start
 			results[i], errs[i] = cache.EnabledProviders(ctx)
-		}(i)
+		})
 	}
 
 	close(start)

coderd/x/nats/pubsub_test.go

@@ -139,11 +139,9 @@ func TestPubsub(t *testing.T) {
 
 		var first, second error
 		var wg sync.WaitGroup
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			first = ps.Close()
-		}()
+		})
 		wg.Wait()
 		second = ps.Close()
 		assert.NoError(t, first)