sourcemap: fix data race in test (#5842)

Fix data race in TestFleetFetch: as there are two
servers, one may update hasAuth concurrently with
the test checking the value.

Change the way the auth header is checked to be
similar to how the header would be checked in a
real fleet-server, and respond with 401 if the
auth header is invalid.

sourcemap/fleet_store_test.go

@@ -22,7 +22,6 @@ import (
 	"context"
 	"net/http"
 	"net/http/httptest"
-	"sync"
 	"sync/atomic"
 	"testing"
 
@@ -34,8 +33,6 @@ import (
 
 func TestFleetFetch(t *testing.T) {
 	var (
-		hasAuth       = true
-		mu            sync.Mutex
 		apikey        = "supersecret"
 		name          = "webapp"
 		version       = "1.0.0"
@@ -46,10 +43,10 @@ func TestFleetFetch(t *testing.T) {
 
 	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		assert.Equal(t, sourceMapPath, r.URL.Path)
-		auth := r.Header.Get("Authorization")
-		mu.Lock()
-		hasAuth = hasAuth && (auth == "ApiKey "+apikey)
-		mu.Unlock()
+		if auth := r.Header.Get("Authorization"); auth != "ApiKey "+apikey {
+			w.WriteHeader(http.StatusUnauthorized)
+			return
+		}
 		// zlib compress
 		wr := zlib.NewWriter(w)
 		defer wr.Close()
@@ -84,7 +81,6 @@ func TestFleetFetch(t *testing.T) {
 	require.NoError(t, err)
 
 	assert.Contains(t, gotRes, "webpack:///bundle.js")
-	assert.True(t, hasAuth)
 }
 
 func TestFailedAndSuccessfulFleetHostsFetch(t *testing.T) {