From 5f218a43fdad9674c00bc41170602730f034187d Mon Sep 17 00:00:00 2001
From: Emmanuel Odeke <emm.odeke@gmail.com>
Date: Fri, 13 Oct 2017 00:11:20 -0600
Subject: [PATCH] rpc/client: use compile time assertions instead of methods

---
 rpc/client/httpclient.go  | 21 ++++++---------------
 rpc/client/localclient.go | 11 ++++-------
 rpc/client/mock/abci.go   | 16 +++++-----------
 rpc/client/mock/client.go |  4 +---
 rpc/client/mock/status.go | 11 ++++-------
 5 files changed, 20 insertions(+), 43 deletions(-)

diff --git a/rpc/client/httpclient.go b/rpc/client/httpclient.go
index b00c97d23..2b78e9767 100644
--- a/rpc/client/httpclient.go
+++ b/rpc/client/httpclient.go
@@ -39,17 +39,12 @@ func NewHTTP(remote, wsEndpoint string) *HTTP {
 	}
 }
 
-func (c *HTTP) _assertIsClient() Client {
-	return c
-}
-
-func (c *HTTP) _assertIsNetworkClient() NetworkClient {
-	return c
-}
-
-func (c *HTTP) _assertIsEventSwitch() types.EventSwitch {
-	return c
-}
+var (
+	_ Client            = (*HTTP)(nil)
+	_ NetworkClient     = (*HTTP)(nil)
+	_ types.EventSwitch = (*HTTP)(nil)
+	_ types.EventSwitch = (*WSEvents)(nil)
+)
 
 func (c *HTTP) Status() (*ctypes.ResultStatus, error) {
 	result := new(ctypes.ResultStatus)
@@ -216,10 +211,6 @@ func newWSEvents(remote, endpoint string) *WSEvents {
 	}
 }
 
-func (w *WSEvents) _assertIsEventSwitch() types.EventSwitch {
-	return w
-}
-
 // Start is the only way I could think the extend OnStart from
 // events.eventSwitch.  If only it wasn't private...
 // BaseService.Start -> eventSwitch.OnStart -> WSEvents.Start
diff --git a/rpc/client/localclient.go b/rpc/client/localclient.go
index 134f935ca..d12a5a84f 100644
--- a/rpc/client/localclient.go
+++ b/rpc/client/localclient.go
@@ -41,13 +41,10 @@ func NewLocal(node *nm.Node) Local {
 	}
 }
 
-func (c Local) _assertIsClient() Client {
-	return c
-}
-
-func (c Local) _assertIsNetworkClient() NetworkClient {
-	return c
-}
+var (
+	_ Client        = Local{}
+	_ NetworkClient = Local{}
+)
 
 func (c Local) Status() (*ctypes.ResultStatus, error) {
 	return core.Status()
diff --git a/rpc/client/mock/abci.go b/rpc/client/mock/abci.go
index db3fa4f1d..a02971342 100644
--- a/rpc/client/mock/abci.go
+++ b/rpc/client/mock/abci.go
@@ -16,9 +16,11 @@ type ABCIApp struct {
 	App abci.Application
 }
 
-func (a ABCIApp) _assertABCIClient() client.ABCIClient {
-	return a
-}
+var (
+	_ client.ABCIClient = ABCIApp{}
+	_ client.ABCIClient = ABCIMock{}
+	_ client.ABCIClient = (*ABCIRecorder)(nil)
+)
 
 func (a ABCIApp) ABCIInfo() (*ctypes.ResultABCIInfo, error) {
 	return &ctypes.ResultABCIInfo{a.App.Info(abci.RequestInfo{version.Version})}, nil
@@ -67,10 +69,6 @@ type ABCIMock struct {
 	Broadcast       Call
 }
 
-func (m ABCIMock) _assertABCIClient() client.ABCIClient {
-	return m
-}
-
 func (m ABCIMock) ABCIInfo() (*ctypes.ResultABCIInfo, error) {
 	res, err := m.Info.GetResponse(nil)
 	if err != nil {
@@ -126,10 +124,6 @@ func NewABCIRecorder(client client.ABCIClient) *ABCIRecorder {
 	}
 }
 
-func (r *ABCIRecorder) _assertABCIClient() client.ABCIClient {
-	return r
-}
-
 type QueryArgs struct {
 	Path  string
 	Data  data.Bytes
diff --git a/rpc/client/mock/client.go b/rpc/client/mock/client.go
index f32694edd..fd02ebdf2 100644
--- a/rpc/client/mock/client.go
+++ b/rpc/client/mock/client.go
@@ -37,9 +37,7 @@ type Client struct {
 	types.EventSwitch
 }
 
-func (c Client) _assertIsClient() client.Client {
-	return c
-}
+var _ client.Client = Client{}
 
 // Call is used by recorders to save a call and response.
 // It can also be used to configure mock responses.
diff --git a/rpc/client/mock/status.go b/rpc/client/mock/status.go
index af0f5335d..58b29d573 100644
--- a/rpc/client/mock/status.go
+++ b/rpc/client/mock/status.go
@@ -10,9 +10,10 @@ type StatusMock struct {
 	Call
 }
 
-func (m *StatusMock) _assertStatusClient() client.StatusClient {
-	return m
-}
+var (
+	_ client.StatusClient = (*StatusMock)(nil)
+	_ client.StatusClient = (*StatusRecorder)(nil)
+)
 
 func (m *StatusMock) Status() (*ctypes.ResultStatus, error) {
 	res, err := m.GetResponse(nil)
@@ -36,10 +37,6 @@ func NewStatusRecorder(client client.StatusClient) *StatusRecorder {
 	}
 }
 
-func (r *StatusRecorder) _assertStatusClient() client.StatusClient {
-	return r
-}
-
 func (r *StatusRecorder) addCall(call Call) {
 	r.Calls = append(r.Calls, call)
 }