diff --git a/gitea/client_test.go b/gitea/client_test.go
index 12cb8d7..ddd4285 100644
--- a/gitea/client_test.go
+++ b/gitea/client_test.go
@@ -1,3 +1,5 @@
+//go:build e2e
+
 /*
 Copyright 2023 The Flux CD contributors.
 
@@ -17,49 +19,63 @@ limitations under the License.
 package gitea
 
 import (
+	"net/url"
+	"os"
+	"regexp"
 	"testing"
 
 	"github.com/fluxcd/go-git-providers/gitprovider"
 )
 
 func Test_DomainVariations(t *testing.T) {
+
+	giteaBaseUrl = "http://try.gitea.io"
+	if giteaBaseUrlVar := os.Getenv("GITEA_BASE_URL"); giteaBaseUrlVar != "" {
+		giteaBaseUrl = giteaBaseUrlVar
+	}
+
+	u, err := url.Parse(giteaBaseUrl)
+	if err != nil {
+		t.Fatalf("failed parsing base URL %q: %s", giteaBaseUrl, err)
+	}
+
 	tests := []struct {
-		name         string
-		opts         gitprovider.ClientOption
-		want         string
-		expectedErrs []error
+		name               string
+		opts               gitprovider.ClientOption
+		want               string
+		expectedErrPattern string
 	}{
 		{
-			name: "try.gitea.io domain",
-			opts: gitprovider.WithDomain("try.gitea.io"),
-			want: "try.gitea.io",
+			name:               "custom domain without protocol uses HTTPS by default",
+			opts:               gitprovider.WithDomain(u.Host),
+			expectedErrPattern: "http: server gave HTTP response to HTTPS client",
 		},
 		{
-			name: "custom domain without protocol",
-			opts: gitprovider.WithDomain("try.gitea.io"),
-			want: "try.gitea.io",
-		},
-		{
-			name: "custom domain with https protocol",
-			opts: gitprovider.WithDomain("https://try.gitea.io"),
-			want: "https://try.gitea.io",
-		},
-		{
-			name: "custom domain with http protocol",
-			opts: gitprovider.WithDomain("http://try.gitea.io"),
-			want: "http://try.gitea.io",
+			name: "custom domain with scheme",
+			opts: gitprovider.WithDomain(giteaBaseUrl),
+			want: giteaBaseUrl,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			c1, err := NewClient("token", tt.opts)
 			if err != nil {
-				t.Fatal(err)
+				if tt.expectedErrPattern == "" {
+					t.Fatalf("unexpected error: %s", err)
+				}
+				m, mErr := regexp.MatchString(tt.expectedErrPattern, err.Error())
+				if mErr != nil {
+					t.Fatalf("unexpected error from matching error: %s", mErr)
+				}
+				if !m {
+					t.Fatalf("unexpected error %q; expected %q", err, tt.expectedErrPattern)
+				}
+				return // all assertions passed
+			} else if tt.expectedErrPattern != "" {
+				t.Fatalf("expected error %q but got none", tt.expectedErrPattern)
 			}
-			assertEqual(t, tt.want, c1.SupportedDomain())
 
-			c2, _ := NewClient("token", tt.opts)
-			assertEqual(t, tt.want, c2.SupportedDomain())
+			assertEqual(t, tt.want, c1.SupportedDomain())
 		})
 	}
 }