return error if an external HTTP rule has no matching method

Author: andrascz

protoc-gen-grpc-gateway/descriptor/registry.go

@@ -268,6 +268,29 @@ func (r *Registry) AddExternalHTTPRule(qualifiedMethodName string, rule *annotat
 	r.externalHTTPRules[qualifiedMethodName] = append(r.externalHTTPRules[qualifiedMethodName], rule)
 }
 
+// UnboundExternalHTTPRules returns the list of External HTTPRules
+// which does not have a matching method in the registry
+func (r *Registry) UnboundExternalHTTPRules() []string {
+	allServiceMethods := make(map[string]struct{})
+	for _, f := range r.files {
+		for _, s := range f.GetService() {
+			svc := &Service{File: f, ServiceDescriptorProto: s}
+			for _, m := range s.GetMethod() {
+				method := &Method{Service: svc, MethodDescriptorProto: m}
+				allServiceMethods[method.FQMN()] = struct{}{}
+			}
+		}
+	}
+
+	var missingMethods []string
+	for httpRuleMethod := range r.externalHTTPRules {
+		if _, ok := allServiceMethods[httpRuleMethod]; !ok {
+			missingMethods = append(missingMethods, httpRuleMethod)
+		}
+	}
+	return missingMethods
+}
+
 // AddPkgMap adds a mapping from a .proto file to proto package name.
 func (r *Registry) AddPkgMap(file, protoPkg string) {
 	r.pkgMap[file] = protoPkg

protoc-gen-grpc-gateway/descriptor/registry_test.go

@@ -586,3 +586,43 @@ func TestLoadGoPackageInputPath(t *testing.T) {
 		t.Errorf("file.GoPkg = %#v; want %#v", got, want)
 	}
 }
+
+func TestUnboundExternalHTTPRules(t *testing.T) {
+	reg := NewRegistry()
+	methodName := ".example.ExampleService.Echo"
+	reg.AddExternalHTTPRule(methodName, nil)
+	assertStringSlice(t, "unbound external HTTP rules", reg.UnboundExternalHTTPRules(), []string{methodName})
+	loadFile(t, reg, `
+		name: "path/to/example.proto",
+		package: "example"
+		message_type <
+			name: "StringMessage"
+			field <
+				name: "string"
+				number: 1
+				label: LABEL_OPTIONAL
+				type: TYPE_STRING
+			>
+		>
+		service <
+			name: "ExampleService"
+			method <
+				name: "Echo"
+				input_type: "StringMessage"
+				output_type: "StringMessage"
+			>
+		>
+	`)
+	assertStringSlice(t, "unbound external HTTP rules", reg.UnboundExternalHTTPRules(), []string{})
+}
+
+func assertStringSlice(t *testing.T, message string, got, want []string) {
+	if len(got) != len(want) {
+		t.Errorf("%s = %#v len(%d); want %#v len(%d)", message, got, len(got), want, len(want))
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Errorf("%s[%d] = %#v; want %#v", message, i, got[i], want[i])
+		}
+	}
+}

protoc-gen-grpc-gateway/main.go

@@ -103,6 +103,11 @@ func main() {
 		emitError(err)
 		return
 	}
+	unboundHTTPRules := reg.UnboundExternalHTTPRules()
+	if len(unboundHTTPRules) != 0 {
+		emitError(fmt.Errorf("HTTP rules without a matching selector: %s", strings.Join(unboundHTTPRules, ", ")))
+		return
+	}
 
 	var targets []*descriptor.File
 	for _, target := range req.FileToGenerate {