Add VerifyHost handler to ghttp (#698)

Host is a field on the http.Request struct and it is useful to test that
its value is correctly set. One cannot rely on checking the header (ie
by VerifyHeader) alone

Signed-off-by: toby lorne <toby@toby.codes>

ghttp/handlers.go

@@ -112,6 +112,21 @@ func (g GHTTPWithGomega) VerifyHeaderKV(key string, values ...string) http.Handl
 	return g.VerifyHeader(http.Header{key: values})
 }
 
+// VerifyHost returns a handler that verifies the host of a request matches the expected host
+// Host is a special header in net/http, which is not set on the request.Header but rather on the Request itself
+//
+// Host may be a string or a matcher
+func (g GHTTPWithGomega) VerifyHost(host interface{}) http.HandlerFunc {
+	return func(w http.ResponseWriter, req *http.Request) {
+		switch p := host.(type) {
+		case types.GomegaMatcher:
+			g.gomega.Expect(req.Host).Should(p, "Host mismatch")
+		default:
+			g.gomega.Expect(req.Host).Should(Equal(host), "Host mismatch")
+		}
+	}
+}
+
 //VerifyBody returns a handler that verifies that the body of the request matches the passed in byte array.
 //It does this using Equal().
 func (g GHTTPWithGomega) VerifyBody(expectedBody []byte) http.HandlerFunc {
@@ -358,6 +373,10 @@ func VerifyHeaderKV(key string, values ...string) http.HandlerFunc {
 	return NewGHTTPWithGomega(gomega.Default).VerifyHeaderKV(key, values...)
 }
 
+func VerifyHost(host interface{}) http.HandlerFunc {
+	return NewGHTTPWithGomega(gomega.Default).VerifyHost(host)
+}
+
 func VerifyBody(expectedBody []byte) http.HandlerFunc {
 	return NewGHTTPWithGomega(gomega.Default).VerifyBody(expectedBody)
 }

ghttp/test_server_test.go

@@ -499,6 +499,69 @@ var _ = Describe("TestServer", func() {
 			})
 		})
 
+		Describe("VerifyHost", func() {
+			var (
+				err error
+				req *http.Request
+			)
+
+			BeforeEach(func() {
+				req, err = http.NewRequest("GET", s.URL()+"/host", nil)
+				Expect(err).ShouldNot(HaveOccurred())
+			})
+
+			When("passed a matcher for host", func() {
+				BeforeEach(func() {
+					s.AppendHandlers(CombineHandlers(
+						VerifyRequest("GET", "/host"),
+						VerifyHost(Equal("my-host")),
+					))
+				})
+
+				It("should verify the host", func() {
+					req.Host = "my-host"
+
+					resp, err = http.DefaultClient.Do(req)
+					Expect(err).ShouldNot(HaveOccurred())
+				})
+
+				It("should reject an invalid host", func() {
+					req.Host = "not-my-host"
+
+					failures := InterceptGomegaFailures(func() {
+						http.DefaultClient.Do(req)
+					})
+					Expect(failures).Should(HaveLen(1))
+				})
+			})
+
+			When("passed a string for host", func() {
+				BeforeEach(func() {
+					s.AppendHandlers(CombineHandlers(
+						VerifyRequest("GET", "/host"),
+						VerifyHost("my-host"),
+					))
+				})
+
+				It("should verify the host", func() {
+					req.Host = "my-host"
+
+					resp, err = http.DefaultClient.Do(req)
+					Expect(err).ShouldNot(HaveOccurred())
+				})
+
+				It("should reject an invalid host", func() {
+					req.Host = "not-my-host"
+
+					failures := InterceptGomegaFailures(func() {
+						http.DefaultClient.Do(req)
+					})
+					Expect(failures).Should(HaveLen(1))
+				})
+			})
+
+		})
+
 		Describe("VerifyBody", func() {
 			BeforeEach(func() {
 				s.AppendHandlers(CombineHandlers(