Better error management

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 #### Changed
 - (#282) Branch support added. You can now specify your branches with a `#branch` fragment at the end of your git url. E.g.: https://github.com/mesg-foundation/service-ethereum-erc20#websocket
+- (#299) Add more user friendly errors when failing to connect to the Core or Docker
 
 #### Added
 - (#242) Add more details in command `mesg-core service validate`

cmd/utils/error.go

@@ -4,13 +4,43 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/docker/docker/client"
 	"github.com/logrusorgru/aurora"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+const (
+	cannotReachTheCore = "Cannot reach the Core"
+	startCore          = "Please start the core by running: mesg-core start"
+	cannotReachDocker  = "Cannot reach Docker"
+	installDocker      = "Please make sure Docker is running.\nIf Docker is not installed on your machine you can install it here: https://store.docker.com/search?type=edition&offering=community"
 )
 
 // HandleError display the error and stop the process if error exist
 func HandleError(err error) {
 	if err != nil {
-		fmt.Println(aurora.Red(err))
+		fmt.Println(errorMessage(err))
 		os.Exit(0)
 	}
 }
+
+func errorMessage(err error) string {
+	switch {
+	case coreConnectionError(err):
+		return aurora.Sprintf("%s\n%s", aurora.Red(cannotReachTheCore), startCore)
+	case dockerDaemonError(err):
+		return aurora.Sprintf("%s\n%s", aurora.Red(cannotReachDocker), installDocker)
+	default:
+		return aurora.Red(err.Error()).String()
+	}
+}
+
+func coreConnectionError(err error) bool {
+	s := status.Convert(err)
+	return s.Code() == codes.Unavailable
+}
+
+func dockerDaemonError(err error) bool {
+	return client.IsErrConnectionFailed(err)
+}

cmd/utils/error_test.go

@@ -0,0 +1,36 @@
+package utils
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/docker/docker/client"
+	"github.com/stvp/assert"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+var testCoreConnectionErr = status.Error(codes.Unavailable, "test")
+var testDockerConnectionErr = client.ErrorConnectionFailed("test")
+
+func TestCoreConnectionError(t *testing.T) {
+	assert.True(t, coreConnectionError(testCoreConnectionErr))
+	assert.False(t, coreConnectionError(nil))
+	assert.False(t, coreConnectionError(errors.New("test")))
+}
+
+func TestDockerDaemonError(t *testing.T) {
+	assert.True(t, dockerDaemonError(testDockerConnectionErr))
+	assert.False(t, dockerDaemonError(nil))
+	assert.False(t, dockerDaemonError(errors.New("test")))
+}
+
+func TestErrorMessage(t *testing.T) {
+	assert.Contains(t, cannotReachTheCore, errorMessage(testCoreConnectionErr))
+	assert.Contains(t, startCore, errorMessage(testCoreConnectionErr))
+
+	assert.Contains(t, cannotReachDocker, errorMessage(testDockerConnectionErr))
+	assert.Contains(t, installDocker, errorMessage(testDockerConnectionErr))
+
+	assert.Contains(t, "errorX", errorMessage(errors.New("errorX")))
+}