Add unimplemented gRPC server embeds to mock servers (#179)

Makefile

@@ -83,6 +83,9 @@ grpc-mock:
 	mockgen -package operatorservicemock -source operatorservice/v1/service_grpc.pb.go -destination operatorservicemock/v1/service_grpc.pb.mock.go
 	mockgen -package workflowservicemock -source workflowservice/v1/service_grpc.pb.go -destination workflowservicemock/v1/service_grpc.pb.mock.go
 	mockgen -package cloudservicemock -source cloud/cloudservice/v1/service_grpc.pb.go -destination cloud/cloudservicemock/v1/service_grpc.pb.mock.go
+	go run ./cmd/mockgen-fix OperatorService operatorservicemock/v1/service_grpc.pb.mock.go
+	go run ./cmd/mockgen-fix WorkflowService workflowservicemock/v1/service_grpc.pb.mock.go
+	go run ./cmd/mockgen-fix CloudService cloud/cloudservicemock/v1/service_grpc.pb.mock.go
 
 .PHONY: proxy
 proxy:

cmd/mockgen-fix/main.go

@@ -0,0 +1,86 @@
+// The MIT License
+//
+// Copyright (c) 2022 Temporal Technologies Inc.  All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package main
+
+import (
+	"fmt"
+	"go/format"
+	"log"
+	"os"
+	"strings"
+)
+
+func main() {
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run() error {
+	// This code fixes the generated mock service server code to properly embed
+	// the necessary unimplemented struct and add the interface assertion
+
+	if len(os.Args) != 3 {
+		return fmt.Errorf("must provide service name and code filename as arguments")
+	}
+	// Read file
+	b, err := os.ReadFile(os.Args[2])
+	if err != nil {
+		return fmt.Errorf("unable to read file: %w", err)
+	}
+	source := string(b)
+	serviceName := os.Args[1]
+
+	// Find the first "Server struct {" location
+	toFind := fmt.Sprintf("Mock%vServer struct {\n", serviceName)
+	structIndex := strings.Index(source, toFind)
+	if structIndex < 0 || strings.LastIndex(source, toFind) != structIndex {
+		return fmt.Errorf("expected single server struct in file")
+	}
+	structIndex += len(toFind)
+
+	// At the first newline we need to embed the unimplemented server
+	source = source[:structIndex] +
+		fmt.Sprintf("\t%v.Unimplemented%vServer\n", strings.ToLower(serviceName), serviceName) +
+		source[structIndex:]
+
+	// After the closing brace, we need to add the type assertion to ensure
+	// interface conformance
+	endBrace := structIndex + strings.Index(source[structIndex:], "}\n") + 2
+	source = source[:endBrace] +
+		fmt.Sprintf(
+			"\nvar _ %v.%vServer = (*Mock%vServer)(nil)\n\n",
+			strings.ToLower(serviceName),
+			serviceName,
+			serviceName,
+		) +
+		source[endBrace:]
+
+	// Format and write
+	if b, err := format.Source([]byte(source)); err != nil {
+		return fmt.Errorf("failed formatting: %w", err)
+	} else if err := os.WriteFile(os.Args[2], b, 0644); err != nil {
+		return fmt.Errorf("failed writing: %w", err)
+	}
+	return nil
+}