Support ResponseHeaderModifier filter

pkg/middlewares/gatewayapi/headermodifier/response_header_modifier_test.go

@@ -0,0 +1,121 @@
+package headermodifier
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/traefik/traefik/v3/pkg/config/dynamic"
+	"github.com/traefik/traefik/v3/pkg/testhelpers"
+)
+
+func TestResponseHeaderModifier(t *testing.T) {
+	testCases := []struct {
+		desc            string
+		config          dynamic.HeaderModifier
+		responseHeaders http.Header
+		expectedHeaders http.Header
+	}{
+		{
+			desc:            "no config",
+			config:          dynamic.HeaderModifier{},
+			expectedHeaders: map[string][]string{},
+		},
+		{
+			desc: "set header",
+			config: dynamic.HeaderModifier{
+				Set: map[string]string{"Foo": "Bar"},
+			},
+			expectedHeaders: map[string][]string{"Foo": {"Bar"}},
+		},
+		{
+			desc: "set header with existing headers",
+			config: dynamic.HeaderModifier{
+				Set: map[string]string{"Foo": "Bar"},
+			},
+			responseHeaders: map[string][]string{"Foo": {"Baz"}, "Bar": {"Foo"}},
+			expectedHeaders: map[string][]string{"Foo": {"Bar"}, "Bar": {"Foo"}},
+		},
+		{
+			desc: "set multiple headers with existing headers",
+			config: dynamic.HeaderModifier{
+				Set: map[string]string{"Foo": "Bar", "Bar": "Foo"},
+			},
+			responseHeaders: map[string][]string{"Foo": {"Baz"}, "Bar": {"Foobar"}},
+			expectedHeaders: map[string][]string{"Foo": {"Bar"}, "Bar": {"Foo"}},
+		},
+		{
+			desc: "add header",
+			config: dynamic.HeaderModifier{
+				Add: map[string]string{"Foo": "Bar"},
+			},
+			expectedHeaders: map[string][]string{"Foo": {"Bar"}},
+		},
+		{
+			desc: "add header with existing headers",
+			config: dynamic.HeaderModifier{
+				Add: map[string]string{"Foo": "Bar"},
+			},
+			responseHeaders: map[string][]string{"Foo": {"Baz"}, "Bar": {"Foo"}},
+			expectedHeaders: map[string][]string{"Foo": {"Baz", "Bar"}, "Bar": {"Foo"}},
+		},
+		{
+			desc: "add multiple headers with existing headers",
+			config: dynamic.HeaderModifier{
+				Add: map[string]string{"Foo": "Bar", "Bar": "Foo"},
+			},
+			responseHeaders: map[string][]string{"Foo": {"Baz"}, "Bar": {"Foobar"}},
+			expectedHeaders: map[string][]string{"Foo": {"Baz", "Bar"}, "Bar": {"Foobar", "Foo"}},
+		},
+		{
+			desc: "remove header",
+			config: dynamic.HeaderModifier{
+				Remove: []string{"Foo"},
+			},
+			expectedHeaders: map[string][]string{},
+		},
+		{
+			desc: "remove header with existing headers",
+			config: dynamic.HeaderModifier{
+				Remove: []string{"Foo"},
+			},
+			responseHeaders: map[string][]string{"Foo": {"Baz"}, "Bar": {"Foo"}},
+			expectedHeaders: map[string][]string{"Bar": {"Foo"}},
+		},
+		{
+			desc: "remove multiple headers with existing headers",
+			config: dynamic.HeaderModifier{
+				Remove: []string{"Foo", "Bar"},
+			},
+			responseHeaders: map[string][]string{"Foo": {"Bar"}, "Bar": {"Foo"}, "Baz": {"Bar"}},
+			expectedHeaders: map[string][]string{"Baz": {"Bar"}},
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			var nextCallCount int
+			next := http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+				nextCallCount++
+				rw.WriteHeader(http.StatusOK)
+			})
+
+			handler := NewResponseHeaderModifier(context.Background(), next, test.config, "foo-response-header-modifier")
+
+			req := testhelpers.MustNewRequest(http.MethodGet, "http://localhost", nil)
+			resp := httptest.NewRecorder()
+			for k, v := range test.responseHeaders {
+				resp.Header()[k] = v
+			}
+
+			handler.ServeHTTP(resp, req)
+
+			assert.Equal(t, 1, nextCallCount)
+			assert.Equal(t, test.expectedHeaders, resp.Header())
+		})
+	}
+}