diff --git a/internal/notifier/google_chat_test.go b/internal/notifier/google_chat_test.go
index cb0b4c9d3..6637ae39d 100644
--- a/internal/notifier/google_chat_test.go
+++ b/internal/notifier/google_chat_test.go
@@ -23,10 +23,36 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 
+	eventv1 "github.com/fluxcd/pkg/apis/event/v1beta1"
 	. "github.com/onsi/gomega"
 )
 
+func TestNewGoogleChat(t *testing.T) {
+	t.Run("valid URL", func(t *testing.T) {
+		g := NewWithT(t)
+		gc, err := NewGoogleChat("https://chat.googleapis.com/v1/spaces/test/messages?key=key&token=token", "")
+		g.Expect(err).ToNot(HaveOccurred())
+		g.Expect(gc.URL).To(Equal("https://chat.googleapis.com/v1/spaces/test/messages?key=key&token=token"))
+		g.Expect(gc.ProxyURL).To(BeEmpty())
+	})
+
+	t.Run("with proxy", func(t *testing.T) {
+		g := NewWithT(t)
+		gc, err := NewGoogleChat("https://chat.googleapis.com/v1/spaces/test/messages", "http://proxy:8080")
+		g.Expect(err).ToNot(HaveOccurred())
+		g.Expect(gc.ProxyURL).To(Equal("http://proxy:8080"))
+	})
+
+	t.Run("invalid URL", func(t *testing.T) {
+		g := NewWithT(t)
+		_, err := NewGoogleChat("not a url", "")
+		g.Expect(err).To(HaveOccurred())
+		g.Expect(err.Error()).To(ContainSubstring("invalid Google Chat hook URL"))
+	})
+}
+
 func TestGoogleChat_Post(t *testing.T) {
 	g := NewWithT(t)
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -36,6 +62,7 @@ func TestGoogleChat_Post(t *testing.T) {
 		err = json.Unmarshal(b, &payload)
 		g.Expect(err).ToNot(HaveOccurred())
 
+		g.Expect(payload.Cards).To(HaveLen(1))
 		g.Expect(payload.Cards[0].Header.Title).To(Equal("gitrepository/webapp.gitops-system"))
 		g.Expect(payload.Cards[0].Header.SubTitle).To(Equal("source-controller"))
 		g.Expect(payload.Cards[0].Sections[0].Widgets[0].TextParagraph.Text).To(Equal("message"))
@@ -50,3 +77,66 @@ func TestGoogleChat_Post(t *testing.T) {
 	err = google_chat.Post(context.TODO(), testEvent())
 	g.Expect(err).ToNot(HaveOccurred())
 }
+
+func TestGoogleChat_PostErrorSeverity(t *testing.T) {
+	g := NewWithT(t)
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		b, err := io.ReadAll(r.Body)
+		g.Expect(err).ToNot(HaveOccurred())
+		var payload = GoogleChatPayload{}
+		err = json.Unmarshal(b, &payload)
+		g.Expect(err).ToNot(HaveOccurred())
+
+		g.Expect(payload.Cards[0].Sections[0].Widgets[0].TextParagraph.Text).To(ContainSubstring(`color="#ff0000"`))
+		g.Expect(payload.Cards[0].Sections[0].Widgets[0].TextParagraph.Text).To(ContainSubstring("message"))
+	}))
+	defer ts.Close()
+
+	gc, err := NewGoogleChat(ts.URL, "")
+	g.Expect(err).ToNot(HaveOccurred())
+
+	event := testEvent()
+	event.Severity = eventv1.EventSeverityError
+	err = gc.Post(context.TODO(), event)
+	g.Expect(err).ToNot(HaveOccurred())
+}
+
+func TestGoogleChat_PostNoMetadata(t *testing.T) {
+	g := NewWithT(t)
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		b, err := io.ReadAll(r.Body)
+		g.Expect(err).ToNot(HaveOccurred())
+		var payload = GoogleChatPayload{}
+		err = json.Unmarshal(b, &payload)
+		g.Expect(err).ToNot(HaveOccurred())
+
+		// Only message section, no metadata section
+		g.Expect(payload.Cards[0].Sections).To(HaveLen(1))
+	}))
+	defer ts.Close()
+
+	gc, err := NewGoogleChat(ts.URL, "")
+	g.Expect(err).ToNot(HaveOccurred())
+
+	event := testEvent()
+	event.Metadata = nil
+	err = gc.Post(context.TODO(), event)
+	g.Expect(err).ToNot(HaveOccurred())
+}
+
+func TestGoogleChat_PostServerError(t *testing.T) {
+	g := NewWithT(t)
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer ts.Close()
+
+	gc, err := NewGoogleChat(ts.URL, "")
+	g.Expect(err).ToNot(HaveOccurred())
+
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	err = gc.Post(ctx, testEvent())
+	g.Expect(err).To(HaveOccurred())
+	g.Expect(err.Error()).To(ContainSubstring("postMessage failed"))
+}