1 files changed, 52 insertions, 0 deletions
diff --git a/src/net/http/fcgi/fcgi_test.go b/src/net/http/fcgi/fcgi_test.go
index e9d2b34023..4a27a12c35 100644
--- a/src/net/http/fcgi/fcgi_test.go
+++ b/src/net/http/fcgi/fcgi_test.go
@@ -10,6 +10,7 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"strings"
 	"testing"
 )
 
@@ -344,3 +345,54 @@ func TestChildServeReadsEnvVars(t *testing.T) {
 		<-done
 	}
 }
+
+func TestResponseWriterSniffsContentType(t *testing.T) {
+	var tests = []struct {
+		name   string
+		body   string
+		wantCT string
+	}{
+		{
+			name:   "no body",
+			wantCT: "text/plain; charset=utf-8",
+		},
+		{
+			name:   "html",
+			body:   "<html><head><title>test page</title></head><body>This is a body</body></html>",
+			wantCT: "text/html; charset=utf-8",
+		},
+		{
+			name:   "text",
+			body:   strings.Repeat("gopher", 86),
+			wantCT: "text/plain; charset=utf-8",
+		},
+		{
+			name:   "jpg",
+			body:   "\xFF\xD8\xFF" + strings.Repeat("B", 1024),
+			wantCT: "image/jpeg",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			input := make([]byte, len(streamFullRequestStdin))
+			copy(input, streamFullRequestStdin)
+			rc := nopWriteCloser{bytes.NewBuffer(input)}
+			done := make(chan bool)
+			var resp *response
+			c := newChild(rc, http.HandlerFunc(func(
+				w http.ResponseWriter,
+				r *http.Request,
+			) {
+				io.WriteString(w, tt.body)
+				resp = w.(*response)
+				done <- true
+			}))
+			defer c.cleanUp()
+			go c.serve()
+			<-done
+			if got := resp.Header().Get("Content-Type"); got != tt.wantCT {
+				t.Errorf("got a Content-Type of %q; expected it to start with %q", got, tt.wantCT)
+			}
+		})
+	}
+}