test: enable HTTPS redirect tests with expression router (#4614)

test/integration/ingress_https_test.go

@@ -30,8 +30,8 @@ import (
 )
 
 func TestHTTPSRedirect(t *testing.T) {
-	// kong does not support HTTPS redirect yet.
-	skipTestForExpressionRouter(t)
+	// Kong starts to support HTTPS redirect in expression router from 3.4.0.
+	RunWhenKongExpressionRouterWithVersion(t, ">=3.4.0")
 	ctx := context.Background()
 
 	t.Parallel()

test/internal/helpers/kong.go

@@ -90,6 +90,20 @@ func GetKongDBMode(proxyAdminURL *url.URL, kongTestPassword string) (string, err
 
 // GetKongRouterFlavor gets router flavor of Kong using the provided Admin API URL.
 func GetKongRouterFlavor(proxyAdminURL *url.URL, kongTestPassword string) (string, error) {
+	const (
+		// ExpressionRouterMinMajorVersion is the lowest major version of Kong that supports expression router.
+		// Kong below this version supports only "traditional" router, and does not contain "router_flavor" field in root configuration.
+		ExpressionRouterMinMajorVersion = 3
+	)
+	kongVersion, err := GetKongVersion(proxyAdminURL, kongTestPassword)
+	if err != nil {
+		return "", err
+	}
+
+	if kongVersion.Major() < ExpressionRouterMinMajorVersion {
+		return "traditional", nil
+	}
+
 	jsonResp, err := GetKongRootConfig(proxyAdminURL, kongTestPassword)
 	if err != nil {
 		return "", err