Fix issue of gaper not restarting after a previous failure

Close #8

gaper.go

@@ -103,7 +103,8 @@ func run(cfg *Config, chOSSiginal chan os.Signal, builder Builder, runner Runner
 				continue
 			}
 
-			changeRestart = true
+			changeRestart = runner.IsRunning()
+
 			if err := restart(builder, runner); err != nil {
 				return err
 			}

runner.go

@@ -23,6 +23,7 @@ type Runner interface {
 	Kill() error
 	Errors() chan error
 	Exited() bool
+	IsRunning() bool
 	ExitStatus(err error) int
 }
 
@@ -108,6 +109,11 @@ func (r *runner) Exited() bool {
 	return r.command != nil && r.command.ProcessState != nil && r.command.ProcessState.Exited()
 }
 
+// IsRunning returns if the process is running
+func (r *runner) IsRunning() bool {
+	return r.command != nil && r.command.Process != nil && r.command.Process.Pid > 0
+}
+
 // Errors get errors occurred during the build
 func (r *runner) Errors() chan error {
 	return r.errors

testdata/mocks.go

@@ -57,6 +57,12 @@ func (m *MockRunner) Exited() bool {
 	return args.Bool(0)
 }
 
+// IsRunning ...
+func (m *MockRunner) IsRunning() bool {
+	args := m.Called()
+	return args.Bool(0)
+}
+
 // ExitStatus ...
 func (m *MockRunner) ExitStatus(err error) int {
 	args := m.Called()