Adding a feature to control the status code

error.go

@@ -0,0 +1,27 @@
+package lieut
+
+// StatusCodeError represents an error that reports an associated status code.
+type StatusCodeError interface {
+	error
+
+	// StatusCode returns the status code of the error, which can be used by an
+	// app's execution error to know which status code to return.
+	StatusCode() int
+}
+
+type statusCodeError struct {
+	error
+
+	statusCode int
+}
+
+// ErrWithStatusCode takes an error and a status code and returns a type that
+// satisfies StatusCodeError.
+func ErrWithStatusCode(err error, statusCode int) StatusCodeError {
+	return &statusCodeError{error: err, statusCode: statusCode}
+}
+
+// StatusCode returns the status code of the error.
+func (e *statusCodeError) StatusCode() int {
+	return e.statusCode
+}

error_test.go

@@ -0,0 +1,26 @@
+package lieut
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestErrWithStatusCode(t *testing.T) {
+	errMsg := "test error"
+	errCode := 107
+
+	err := errors.New(errMsg)
+
+	statusCodeErr := ErrWithStatusCode(err, errCode)
+	if statusCodeErr == nil {
+		t.Fatal("ErrWithStatusCode returned nil")
+	}
+
+	if gotMsg := statusCodeErr.Error(); gotMsg != errMsg {
+		t.Errorf("err.Error() returned %q, wanted %q", gotMsg, errMsg)
+	}
+
+	if gotCode := statusCodeErr.StatusCode(); gotCode != errCode {
+		t.Errorf("err.Error() returned %v, wanted %v", gotCode, errCode)
+	}
+}

lieut.go

@@ -194,6 +194,10 @@ func (a *MultiCommandApp) CommandNames() []string {
 
 // Run takes a context and arguments, runs the expected command, and returns an
 // exit code.
+//
+// If the init function or command Executor returns a StatusCodeError, then the
+// returned exit code will match that of the value returned by
+// StatusCodeError.StatusCode().
 func (a *SingleCommandApp) Run(ctx context.Context, arguments []string) int {
 	if len(arguments) == 0 {
 		arguments = os.Args[1:]
@@ -216,6 +220,10 @@ func (a *SingleCommandApp) Run(ctx context.Context, arguments []string) int {
 
 // Run takes a context and arguments, runs the expected command, and returns an
 // exit code.
+//
+// If the init function or command Executor returns a StatusCodeError, then the
+// returned exit code will match that of the value returned by
+// StatusCodeError.StatusCode().
 func (a *MultiCommandApp) Run(ctx context.Context, arguments []string) int {
 	if len(arguments) == 0 {
 		arguments = os.Args[1:]
@@ -373,6 +381,11 @@ func (a *app) printErr(err error, pad bool) int {
 
 	fmt.Fprintf(a.errOut, msgFmt, err)
 
+	var statusErr StatusCodeError
+	if errors.As(err, &statusErr) {
+		return statusErr.StatusCode()
+	}
+
 	return 1
 }
 

lieut_test.go

@@ -599,7 +599,7 @@ func TestSingleCommandApp_Run(t *testing.T) {
 	exitCode := app.Run(ctx, args)
 
 	if exitCode != wantedExitCode {
-		t.Errorf("app.Run gave %q, wanted %q", exitCode, wantedExitCode)
+		t.Errorf("app.Run gave %v, wanted %v", exitCode, wantedExitCode)
 	}
 
 	if !initRan {
@@ -638,7 +638,7 @@ func TestSingleCommandApp_Run_EmptyArgsProvided(t *testing.T) {
 	expectedArgs := os.Args[1:]
 
 	if exitCode := app.Run(context.TODO(), nil); exitCode != 0 {
-		t.Errorf("app.Run gave non-zero exit code %q", exitCode)
+		t.Errorf("app.Run gave non-zero exit code %v", exitCode)
 	}
 
 	if capturedArgs[0] != expectedArgs[0] {
@@ -716,6 +716,17 @@ test vTest (%s/%s)
 			wantedOut:      "",
 			wantedErrOut:   "Error: test init error\n",
 		},
+		"initialize returns status code error": {
+			init: func() error {
+				return ErrWithStatusCode(errors.New("test init error"), 101)
+			},
+
+			args: []string{"test"},
+
+			wantedExitCode: 101,
+			wantedOut:      "",
+			wantedErrOut:   "Error: test init error\n",
+		},
 		"execute returns error": {
 			exec: func(ctx context.Context, arguments []string) error {
 				return errors.New("test exec error")
@@ -727,6 +738,17 @@ test vTest (%s/%s)
 			wantedOut:      "",
 			wantedErrOut:   "\nError: test exec error\n",
 		},
+		"execute returns status code error": {
+			exec: func(ctx context.Context, arguments []string) error {
+				return ErrWithStatusCode(errors.New("test exec error"), 217)
+			},
+
+			args: []string{"test"},
+
+			wantedExitCode: 217,
+			wantedOut:      "",
+			wantedErrOut:   "\nError: test exec error\n",
+		},
 	} {
 		t.Run(testName, func(t *testing.T) {
 			var out, errOut bytes.Buffer
@@ -740,7 +762,7 @@ test vTest (%s/%s)
 			exitCode := app.Run(context.TODO(), testData.args)
 
 			if exitCode != testData.wantedExitCode {
-				t.Errorf("app.Run gave %q, wanted %q", exitCode, testData.wantedExitCode)
+				t.Errorf("app.Run gave %v, wanted %v", exitCode, testData.wantedExitCode)
 			}
 
 			if out.String() != testData.wantedOut {
@@ -793,7 +815,7 @@ func TestMultiCommandApp_Run(t *testing.T) {
 	exitCode := app.Run(ctx, args)
 
 	if exitCode != wantedExitCode {
-		t.Errorf("app.Run gave %q, wanted %q", exitCode, wantedExitCode)
+		t.Errorf("app.Run gave %v, wanted %v", exitCode, wantedExitCode)
 	}
 
 	if !initRan {
@@ -837,7 +859,7 @@ func TestMultiCommandApp_Run_EmptyArgsProvided(t *testing.T) {
 	expectedArgs := os.Args[2:]
 
 	if exitCode := app.Run(context.TODO(), nil); exitCode != 0 {
-		t.Errorf("app.Run gave non-zero exit code %q", exitCode)
+		t.Errorf("app.Run gave non-zero exit code %v", exitCode)
 	}
 
 	if capturedArgs[0] != expectedArgs[0] {
@@ -972,6 +994,17 @@ test vTest (%s/%s)
 			wantedOut:      "",
 			wantedErrOut:   "Error: test init error\n",
 		},
+		"initialize returns status code error": {
+			init: func() error {
+				return ErrWithStatusCode(errors.New("test init error"), 101)
+			},
+
+			args: []string{testCommandInfo.Name},
+
+			wantedExitCode: 101,
+			wantedOut:      "",
+			wantedErrOut:   "Error: test init error\n",
+		},
 		"execute returns error": {
 			exec: func(ctx context.Context, arguments []string) error {
 				return errors.New("test exec error")
@@ -983,6 +1016,17 @@ test vTest (%s/%s)
 			wantedOut:      "",
 			wantedErrOut:   "\nError: test exec error\n",
 		},
+		"execute returns status code error": {
+			exec: func(ctx context.Context, arguments []string) error {
+				return ErrWithStatusCode(errors.New("test exec error"), 217)
+			},
+
+			args: []string{testCommandInfo.Name},
+
+			wantedExitCode: 217,
+			wantedOut:      "",
+			wantedErrOut:   "\nError: test exec error\n",
+		},
 		"unknown command": {
 			args: []string{"thiscommanddoesnotexist"},
 
@@ -1019,7 +1063,7 @@ test vTest (%s/%s)
 			exitCode := app.Run(context.TODO(), testData.args)
 
 			if exitCode != testData.wantedExitCode {
-				t.Errorf("app.Run gave %q, wanted %q", exitCode, testData.wantedExitCode)
+				t.Errorf("app.Run gave %v, wanted %v", exitCode, testData.wantedExitCode)
 			}
 
 			if out.String() != testData.wantedOut {