Provide the codegen with an option to generate test clients (#870)

* Provide the codegen with an option to generate test clients

Motivation:

When consuming gRPC it is often helpful to be able to write tests that
ensure the client is integrated correctly. At the moment this is only
possible by running a local gRPC server with a custom service handler to
return the responses you would like to test.

Modifications:

This builds on work in #855, #864, and #865.

This pull request introduces code generation for the test clients. It
provides type-safe wrappers and convenience methods on top of
`FakeChannel` and a code-gen option to enable 'TestClient' generation.

It also removes an `init` requirement on the `GRPCClient` protocol.

Result:

Users can generate test clients.

* Regenerate

* fix type, add assertion

* Add "Remaining"

Author: glbrntt

Makefile

@@ -74,6 +74,14 @@ ECHO_PROTO=Sources/Examples/Echo/Model/echo.proto
 ECHO_PB=$(ECHO_PROTO:.proto=.pb.swift)
 ECHO_GRPC=$(ECHO_PROTO:.proto=.grpc.swift)
 
+# For Echo we'll generate the test client as well.
+${ECHO_GRPC}: ${ECHO_PROTO} ${PROTOC_GEN_GRPC_SWIFT}
+	protoc $< \
+		--proto_path=$(dir $<) \
+		--plugin=${PROTOC_GEN_GRPC_SWIFT} \
+		--grpc-swift_opt=Visibility=Public,TestClient=true \
+		--grpc-swift_out=$(dir $<)
+
 # Generates protobufs and gRPC client and server for the Echo example
 .PHONY:
 generate-echo: ${ECHO_PB} ${ECHO_GRPC}

Sources/Examples/Echo/Model/echo.grpc.swift

@@ -31,65 +31,27 @@ import SwiftProtobuf
 public protocol Echo_EchoClientProtocol: GRPCClient {
   func get(
     _ request: Echo_EchoRequest,
-    callOptions: CallOptions
+    callOptions: CallOptions?
   ) -> UnaryCall<Echo_EchoRequest, Echo_EchoResponse>
 
   func expand(
     _ request: Echo_EchoRequest,
-    callOptions: CallOptions,
+    callOptions: CallOptions?,
     handler: @escaping (Echo_EchoResponse) -> Void
   ) -> ServerStreamingCall<Echo_EchoRequest, Echo_EchoResponse>
 
   func collect(
-    callOptions: CallOptions
+    callOptions: CallOptions?
   ) -> ClientStreamingCall<Echo_EchoRequest, Echo_EchoResponse>
 
   func update(
-    callOptions: CallOptions,
+    callOptions: CallOptions?,
     handler: @escaping (Echo_EchoResponse) -> Void
   ) -> BidirectionalStreamingCall<Echo_EchoRequest, Echo_EchoResponse>
 
 }
 
 extension Echo_EchoClientProtocol {
-  public func get(
-    _ request: Echo_EchoRequest
-  ) -> UnaryCall<Echo_EchoRequest, Echo_EchoResponse> {
-    return self.get(request, callOptions: self.defaultCallOptions)
-  }
-
-  public func expand(
-    _ request: Echo_EchoRequest,
-    handler: @escaping (Echo_EchoResponse) -> Void
-  ) -> ServerStreamingCall<Echo_EchoRequest, Echo_EchoResponse> {
-    return self.expand(request, callOptions: self.defaultCallOptions, handler: handler)
-  }
-
-  public func collect() -> ClientStreamingCall<Echo_EchoRequest, Echo_EchoResponse> {
-    return self.collect(callOptions: self.defaultCallOptions)
-  }
-
-  public func update(
-    handler: @escaping (Echo_EchoResponse) -> Void
-  ) -> BidirectionalStreamingCall<Echo_EchoRequest, Echo_EchoResponse> {
-    return self.update(callOptions: self.defaultCallOptions, handler: handler)
-  }
-
-}
-
-public final class Echo_EchoClient: Echo_EchoClientProtocol {
-  public let channel: GRPCChannel
-  public var defaultCallOptions: CallOptions
-
-  /// Creates a client for the echo.Echo service.
-  ///
-  /// - Parameters:
-  ///   - channel: `GRPCChannel` to the service host.
-  ///   - defaultCallOptions: Options to use for each service call if the user doesn't provide them.
-  public init(channel: GRPCChannel, defaultCallOptions: CallOptions = CallOptions()) {
-    self.channel = channel
-    self.defaultCallOptions = defaultCallOptions
-  }
 
   /// Immediately returns an echo of a request.
   ///
@@ -99,12 +61,12 @@ public final class Echo_EchoClient: Echo_EchoClientProtocol {
   /// - Returns: A `UnaryCall` with futures for the metadata, status and response.
   public func get(
     _ request: Echo_EchoRequest,
-    callOptions: CallOptions
+    callOptions: CallOptions? = nil
   ) -> UnaryCall<Echo_EchoRequest, Echo_EchoResponse> {
     return self.makeUnaryCall(
       path: "/echo.Echo/Get",
       request: request,
-      callOptions: callOptions
+      callOptions: callOptions ?? self.defaultCallOptions
     )
   }
 
@@ -117,13 +79,13 @@ public final class Echo_EchoClient: Echo_EchoClientProtocol {
   /// - Returns: A `ServerStreamingCall` with futures for the metadata and status.
   public func expand(
     _ request: Echo_EchoRequest,
-    callOptions: CallOptions,
+    callOptions: CallOptions? = nil,
     handler: @escaping (Echo_EchoResponse) -> Void
   ) -> ServerStreamingCall<Echo_EchoRequest, Echo_EchoResponse> {
     return self.makeServerStreamingCall(
       path: "/echo.Echo/Expand",
       request: request,
-      callOptions: callOptions,
+      callOptions: callOptions ?? self.defaultCallOptions,
       handler: handler
     )
   }
@@ -137,11 +99,11 @@ public final class Echo_EchoClient: Echo_EchoClientProtocol {
   ///   - callOptions: Call options.
   /// - Returns: A `ClientStreamingCall` with futures for the metadata, status and response.
   public func collect(
-    callOptions: CallOptions
+    callOptions: CallOptions? = nil
   ) -> ClientStreamingCall<Echo_EchoRequest, Echo_EchoResponse> {
     return self.makeClientStreamingCall(
       path: "/echo.Echo/Collect",
-      callOptions: callOptions
+      callOptions: callOptions ?? self.defaultCallOptions
     )
   }
 
@@ -155,17 +117,147 @@ public final class Echo_EchoClient: Echo_EchoClientProtocol {
   ///   - handler: A closure called when each response is received from the server.
   /// - Returns: A `ClientStreamingCall` with futures for the metadata and status.
   public func update(
-    callOptions: CallOptions,
+    callOptions: CallOptions? = nil,
     handler: @escaping (Echo_EchoResponse) -> Void
   ) -> BidirectionalStreamingCall<Echo_EchoRequest, Echo_EchoResponse> {
     return self.makeBidirectionalStreamingCall(
       path: "/echo.Echo/Update",
-      callOptions: callOptions,
+      callOptions: callOptions ?? self.defaultCallOptions,
       handler: handler
     )
   }
 }
 
+public final class Echo_EchoClient: Echo_EchoClientProtocol {
+  public let channel: GRPCChannel
+  public var defaultCallOptions: CallOptions
+
+  /// Creates a client for the echo.Echo service.
+  ///
+  /// - Parameters:
+  ///   - channel: `GRPCChannel` to the service host.
+  ///   - defaultCallOptions: Options to use for each service call if the user doesn't provide them.
+  public init(channel: GRPCChannel, defaultCallOptions: CallOptions = CallOptions()) {
+    self.channel = channel
+    self.defaultCallOptions = defaultCallOptions
+  }
+}
+
+public final class Echo_EchoTestClient: Echo_EchoClientProtocol {
+  private let fakeChannel: FakeChannel
+  public var defaultCallOptions: CallOptions
+
+  public var channel: GRPCChannel {
+    return self.fakeChannel
+  }
+
+  public init(
+    fakeChannel: FakeChannel = FakeChannel(),
+    defaultCallOptions callOptions: CallOptions = CallOptions()
+  ) {
+    self.fakeChannel = fakeChannel
+    self.defaultCallOptions = callOptions
+  }
+
+  /// Make a unary response for the Get RPC. This must be called
+  /// before calling 'get'. See also 'FakeUnaryResponse'.
+  ///
+  /// - Parameter requestHandler: a handler for request parts sent by the RPC.
+  public func makeGetResponseStream(
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  ) -> FakeUnaryResponse<Echo_EchoRequest, Echo_EchoResponse> {
+    return self.fakeChannel.makeFakeUnaryResponse(path: "/echo.Echo/Get", requestHandler: requestHandler)
+  }
+
+  public func enqueueGetResponse(
+    _ response: Echo_EchoResponse,
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  )  {
+    let stream = self.makeGetResponseStream(requestHandler)
+    // This is the only operation on the stream; try! is fine.
+    try! stream.sendMessage(response)
+  }
+
+  /// Returns true if there are response streams enqueued for 'Get'
+  public var hasGetResponsesRemaining: Bool {
+    return self.fakeChannel.hasFakeResponseEnqueued(forPath: "/echo.Echo/Get")
+  }
+
+  /// Make a streaming response for the Expand RPC. This must be called
+  /// before calling 'expand'. See also 'FakeStreamingResponse'.
+  ///
+  /// - Parameter requestHandler: a handler for request parts sent by the RPC.
+  public func makeExpandResponseStream(
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  ) -> FakeStreamingResponse<Echo_EchoRequest, Echo_EchoResponse> {
+    return self.fakeChannel.makeFakeStreamingResponse(path: "/echo.Echo/Expand", requestHandler: requestHandler)
+  }
+
+  public func enqueueExpandResponses(
+    _ responses: [Echo_EchoResponse],
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  )  {
+    let stream = self.makeExpandResponseStream(requestHandler)
+    // These are the only operation on the stream; try! is fine.
+    responses.forEach { try! stream.sendMessage($0) }
+    try! stream.sendEnd()
+  }
+
+  /// Returns true if there are response streams enqueued for 'Expand'
+  public var hasExpandResponsesRemaining: Bool {
+    return self.fakeChannel.hasFakeResponseEnqueued(forPath: "/echo.Echo/Expand")
+  }
+
+  /// Make a unary response for the Collect RPC. This must be called
+  /// before calling 'collect'. See also 'FakeUnaryResponse'.
+  ///
+  /// - Parameter requestHandler: a handler for request parts sent by the RPC.
+  public func makeCollectResponseStream(
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  ) -> FakeUnaryResponse<Echo_EchoRequest, Echo_EchoResponse> {
+    return self.fakeChannel.makeFakeUnaryResponse(path: "/echo.Echo/Collect", requestHandler: requestHandler)
+  }
+
+  public func enqueueCollectResponse(
+    _ response: Echo_EchoResponse,
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  )  {
+    let stream = self.makeCollectResponseStream(requestHandler)
+    // This is the only operation on the stream; try! is fine.
+    try! stream.sendMessage(response)
+  }
+
+  /// Returns true if there are response streams enqueued for 'Collect'
+  public var hasCollectResponsesRemaining: Bool {
+    return self.fakeChannel.hasFakeResponseEnqueued(forPath: "/echo.Echo/Collect")
+  }
+
+  /// Make a streaming response for the Update RPC. This must be called
+  /// before calling 'update'. See also 'FakeStreamingResponse'.
+  ///
+  /// - Parameter requestHandler: a handler for request parts sent by the RPC.
+  public func makeUpdateResponseStream(
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  ) -> FakeStreamingResponse<Echo_EchoRequest, Echo_EchoResponse> {
+    return self.fakeChannel.makeFakeStreamingResponse(path: "/echo.Echo/Update", requestHandler: requestHandler)
+  }
+
+  public func enqueueUpdateResponses(
+    _ responses: [Echo_EchoResponse],
+    _ requestHandler: @escaping (FakeRequestPart<Echo_EchoRequest>) -> () = { _ in }
+  )  {
+    let stream = self.makeUpdateResponseStream(requestHandler)
+    // These are the only operation on the stream; try! is fine.
+    responses.forEach { try! stream.sendMessage($0) }
+    try! stream.sendEnd()
+  }
+
+  /// Returns true if there are response streams enqueued for 'Update'
+  public var hasUpdateResponsesRemaining: Bool {
+    return self.fakeChannel.hasFakeResponseEnqueued(forPath: "/echo.Echo/Update")
+  }
+}
+
 /// To build a server, implement a class that conforms to this protocol.
 public protocol Echo_EchoProvider: CallHandlerProvider {
   /// Immediately returns an echo of a request.

Sources/Examples/HelloWorld/Model/helloworld.grpc.swift

@@ -31,18 +31,29 @@ import SwiftProtobuf
 public protocol Helloworld_GreeterClientProtocol: GRPCClient {
   func sayHello(
     _ request: Helloworld_HelloRequest,
-    callOptions: CallOptions
+    callOptions: CallOptions?
   ) -> UnaryCall<Helloworld_HelloRequest, Helloworld_HelloReply>
 
 }
 
 extension Helloworld_GreeterClientProtocol {
+
+  /// Sends a greeting.
+  ///
+  /// - Parameters:
+  ///   - request: Request to send to SayHello.
+  ///   - callOptions: Call options.
+  /// - Returns: A `UnaryCall` with futures for the metadata, status and response.
   public func sayHello(
-    _ request: Helloworld_HelloRequest
+    _ request: Helloworld_HelloRequest,
+    callOptions: CallOptions? = nil
   ) -> UnaryCall<Helloworld_HelloRequest, Helloworld_HelloReply> {
-    return self.sayHello(request, callOptions: self.defaultCallOptions)
+    return self.makeUnaryCall(
+      path: "/helloworld.Greeter/SayHello",
+      request: request,
+      callOptions: callOptions ?? self.defaultCallOptions
+    )
   }
-
 }
 
 public final class Helloworld_GreeterClient: Helloworld_GreeterClientProtocol {
@@ -58,23 +69,6 @@ public final class Helloworld_GreeterClient: Helloworld_GreeterClientProtocol {
     self.channel = channel
     self.defaultCallOptions = defaultCallOptions
   }
-
-  /// Sends a greeting.
-  ///
-  /// - Parameters:
-  ///   - request: Request to send to SayHello.
-  ///   - callOptions: Call options.
-  /// - Returns: A `UnaryCall` with futures for the metadata, status and response.
-  public func sayHello(
-    _ request: Helloworld_HelloRequest,
-    callOptions: CallOptions
-  ) -> UnaryCall<Helloworld_HelloRequest, Helloworld_HelloReply> {
-    return self.makeUnaryCall(
-      path: "/helloworld.Greeter/SayHello",
-      request: request,
-      callOptions: callOptions
-    )
-  }
 }
 
 /// To build a server, implement a class that conforms to this protocol.