Add matchers for header value prefixes

matchers.go

@@ -127,15 +127,41 @@ func HTTP2() Matcher {
 // request of an HTTP 1 connection.
 func HTTP1HeaderField(name, value string) Matcher {
 	return func(r io.Reader) bool {
-		return matchHTTP1Field(r, name, value)
+		return matchHTTP1Field(r, name, func(gotValue string) bool {
+			return gotValue == value
+		})
 	}
 }
 
-// HTTP2HeaderField resturns a matcher matching the header fields of the first
+// HTTP1HeaderFieldPrefix returns a matcher matching the header fields of the
+// first request of an HTTP 1 connection. If the header with key name has a
+// value prefixed with valuePrefix, this will match.
+func HTTP1HeaderFieldPrefix(name, valuePrefix string) Matcher {
+	return func(r io.Reader) bool {
+		return matchHTTP1Field(r, name, func(gotValue string) bool {
+			return strings.HasPrefix(gotValue, valuePrefix)
+		})
+	}
+}
+
+// HTTP2HeaderField returns a matcher matching the header fields of the first
 // headers frame.
 func HTTP2HeaderField(name, value string) Matcher {
 	return func(r io.Reader) bool {
-		return matchHTTP2Field(ioutil.Discard, r, name, value)
+		return matchHTTP2Field(ioutil.Discard, r, name, func(gotValue string) bool {
+			return gotValue == value
+		})
+	}
+}
+
+// HTTP2HeaderFieldPrefix returns a matcher matching the header fields of the
+// first headers frame. If the header with key name has a value prefixed with
+// valuePrefix, this will match.
+func HTTP2HeaderFieldPrefix(name, valuePrefix string) Matcher {
+	return func(r io.Reader) bool {
+		return matchHTTP2Field(ioutil.Discard, r, name, func(gotValue string) bool {
+			return strings.HasPrefix(gotValue, valuePrefix)
+		})
 	}
 }
 
@@ -144,7 +170,20 @@ func HTTP2HeaderField(name, value string) Matcher {
 // does not block on receiving a SETTING frame.
 func HTTP2MatchHeaderFieldSendSettings(name, value string) MatchWriter {
 	return func(w io.Writer, r io.Reader) bool {
-		return matchHTTP2Field(w, r, name, value)
+		return matchHTTP2Field(w, r, name, func(gotValue string) bool {
+			return gotValue == value
+		})
+	}
+}
+
+// HTTP2MatchHeaderFieldPrefixSendSettings matches the header field prefix
+// and writes the settings to the server. Prefer HTTP2HeaderFieldPrefix over
+// this one, if the client does not block on receiving a SETTING frame.
+func HTTP2MatchHeaderFieldPrefixSendSettings(name, valuePrefix string) MatchWriter {
+	return func(w io.Writer, r io.Reader) bool {
+		return matchHTTP2Field(w, r, name, func(gotValue string) bool {
+			return strings.HasPrefix(gotValue, valuePrefix)
+		})
 	}
 }
 
@@ -169,16 +208,16 @@ func hasHTTP2Preface(r io.Reader) bool {
 	}
 }
 
-func matchHTTP1Field(r io.Reader, name, value string) (matched bool) {
+func matchHTTP1Field(r io.Reader, name string, matches func(string) bool) (matched bool) {
 	req, err := http.ReadRequest(bufio.NewReader(r))
 	if err != nil {
 		return false
 	}
 
-	return req.Header.Get(name) == value
+	return matches(req.Header.Get(name))
 }
 
-func matchHTTP2Field(w io.Writer, r io.Reader, name, value string) (matched bool) {
+func matchHTTP2Field(w io.Writer, r io.Reader, name string, matches func(string) bool) (matched bool) {
 	if !hasHTTP2Preface(r) {
 		return false
 	}
@@ -188,7 +227,7 @@ func matchHTTP2Field(w io.Writer, r io.Reader, name, value string) (matched bool
 	hdec := hpack.NewDecoder(uint32(4<<10), func(hf hpack.HeaderField) {
 		if hf.Name == name {
 			done = true
-			if hf.Value == value {
+			if matches(hf.Value) {
 				matched = true
 			}
 		}