From b9f4b1f59a798cbcfe8cb800036d1db753b71154 Mon Sep 17 00:00:00 2001
From: Will McCutchen <will@mccutch.org>
Date: Mon, 10 Oct 2016 21:22:15 -0700
Subject: [PATCH] Add /response-headers handler

---
 httpbin/handlers.go      | 20 +++++++++++
 httpbin/handlers_test.go | 71 ++++++++++++++++++++++++++++++++++++++++
 httpbin/httpbin.go       |  1 +
 3 files changed, 92 insertions(+)

diff --git a/httpbin/handlers.go b/httpbin/handlers.go
index baccdfa..384abbe 100644
--- a/httpbin/handlers.go
+++ b/httpbin/handlers.go
@@ -176,3 +176,23 @@ func (h *HTTPBin) Status(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(code)
 	}
 }
+
+// ResponseHeaders responds with a map of header values
+func (h *HTTPBin) ResponseHeaders(w http.ResponseWriter, r *http.Request) {
+	args, err := url.ParseQuery(r.URL.RawQuery)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("error parsing query params: %s", err), http.StatusBadRequest)
+		return
+	}
+
+	for k, vs := range args {
+		for _, v := range vs {
+			w.Header().Add(http.CanonicalHeaderKey(k), v)
+		}
+	}
+	body, _ := json.Marshal(args)
+	if contentType := w.Header().Get("Content-Type"); contentType == "" {
+		w.Header().Set("Content-Type", "application/json; encoding=utf-8")
+	}
+	w.Write(body)
+}
diff --git a/httpbin/handlers_test.go b/httpbin/handlers_test.go
index 11bc1ff..7545812 100644
--- a/httpbin/handlers_test.go
+++ b/httpbin/handlers_test.go
@@ -109,6 +109,30 @@ func TestGet__Basic(t *testing.T) {
 	}
 }
 
+func TestGet__WithParams(t *testing.T) {
+	params := url.Values{}
+	params.Set("foo", "foo")
+	params.Add("bar", "bar1")
+	params.Add("bar", "bar2")
+
+	r, _ := http.NewRequest("GET", fmt.Sprintf("/get?%s", params.Encode()), nil)
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, r)
+
+	assertStatusCode(t, w, http.StatusOK)
+	assertContentType(t, w, "application/json; encoding=utf-8")
+
+	var resp *bodyResponse
+	err := json.Unmarshal(w.Body.Bytes(), &resp)
+	if err != nil {
+		t.Fatalf("failed to unmarshal body %s from JSON: %s", w.Body, err)
+	}
+
+	if resp.Args.Encode() != params.Encode() {
+		t.Fatalf("args mismatch: %s != %s", resp.Args.Encode(), params.Encode())
+	}
+}
+
 func TestGet__OnlyAllowsGets(t *testing.T) {
 	r, _ := http.NewRequest("POST", "/get", nil)
 	w := httptest.NewRecorder()
@@ -461,3 +485,50 @@ func TestStatus__Simple(t *testing.T) {
 		}
 	}
 }
+
+func TestResponseHeaders(t *testing.T) {
+	headers := map[string][]string{
+		"Content-Type": {"test/test"},
+		"Foo":          {"foo"},
+		"Bar":          {"bar1, bar2"},
+	}
+
+	params := url.Values{}
+	for k, vs := range headers {
+		for _, v := range vs {
+			params.Add(k, v)
+		}
+	}
+
+	r, _ := http.NewRequest("GET", fmt.Sprintf("/response-headers?%s", params.Encode()), nil)
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, r)
+
+	assertStatusCode(t, w, http.StatusOK)
+
+	for k, expectedValues := range headers {
+		values, ok := w.HeaderMap[k]
+		if !ok {
+			t.Fatalf("expected header %s in response headers", k)
+		}
+		if !reflect.DeepEqual(values, expectedValues) {
+			t.Fatalf("expected key values %#v for header %s, got %#v", expectedValues, k, values)
+		}
+	}
+
+	resp := &http.Header{}
+	err := json.Unmarshal(w.Body.Bytes(), resp)
+	if err != nil {
+		t.Fatalf("failed to unmarshal body %s from JSON: %s", w.Body, err)
+	}
+
+	for k, expectedValues := range headers {
+		values, ok := (*resp)[k]
+		if !ok {
+			t.Fatalf("expected header %s in response body", k)
+		}
+		if !reflect.DeepEqual(values, expectedValues) {
+			t.Fatalf("expected key values %#v for header %s, got %#v", expectedValues, k, values)
+		}
+	}
+}
diff --git a/httpbin/httpbin.go b/httpbin/httpbin.go
index 83a6d26..48e7214 100644
--- a/httpbin/httpbin.go
+++ b/httpbin/httpbin.go
@@ -65,6 +65,7 @@ func (h *HTTPBin) Handler() http.Handler {
 	mux.HandleFunc("/user-agent", h.UserAgent)
 	mux.HandleFunc("/headers", h.Headers)
 	mux.HandleFunc("/status/", h.Status)
+	mux.HandleFunc("/response-headers", h.ResponseHeaders)
 
 	return logger(cors(mux))
 }
-- 
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