updated error messages

Signed-off-by: Patrick Zheng <[email protected]>

plugin/errors.go

@@ -0,0 +1,49 @@
+// Copyright The Notary Project Authors.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package plugin
+
+import "errors"
+
+// ErrNotCompliant is returned by plugin methods when the response is not
+// compliant.
+var ErrNotCompliant = errors.New("plugin not compliant")
+
+// ErrNotRegularFile is returned when the plugin file is not an regular file.
+var ErrNotRegularFile = errors.New("not regular file")
+
+// ErrInstallLowerVersion is returned when installing a plugin with version
+// lower than the exisiting plugin version.
+type ErrInstallLowerVersion struct {
+	Msg string
+}
+
+func (e ErrInstallLowerVersion) Error() string {
+	if e.Msg != "" {
+		return e.Msg
+	}
+	return "installing plugin with version lower than the existing plugin version"
+}
+
+// ErrInstallEqualVersion is returned when installing a plugin with version
+// equal to the exisiting plugin version.
+type ErrInstallEqualVersion struct {
+	Msg string
+}
+
+func (e ErrInstallEqualVersion) Error() string {
+	if e.Msg != "" {
+		return e.Msg
+	}
+	return "installing plugin with version equal to the existing plugin version"
+}

plugin/manager.go

@@ -28,21 +28,6 @@ import (
 	"github.com/notaryproject/notation-go/plugin/proto"
 )
 
-// ErrNotCompliant is returned by plugin methods when the response is not
-// compliant.
-var ErrNotCompliant = errors.New("plugin not compliant")
-
-// ErrNotRegularFile is returned when the plugin file is not an regular file.
-var ErrNotRegularFile = errors.New("not regular file")
-
-// ErrInstallLowerVersion is returned when installing a plugin with version
-// lower than the exisiting plugin version.
-var ErrInstallLowerVersion = errors.New("installing plugin with version lower than the existing plugin version")
-
-// ErrInstallEqualVersion is returned when installing a plugin with version
-// equal to the exisiting plugin version.
-var ErrInstallEqualVersion = errors.New("installing plugin with version equal to the existing plugin version")
-
 // Manager manages plugins installed on the system.
 type Manager interface {
 	Get(ctx context.Context, name string) (Plugin, error)
@@ -146,9 +131,9 @@ func (m *CLIManager) Install(ctx context.Context, filePath string, overwrite boo
 			}
 			switch {
 			case comp < 0:
-				return nil, nil, ErrInstallLowerVersion
+				return nil, nil, ErrInstallLowerVersion{Msg: fmt.Sprintf("The installing plugin version %s is lower than the existing plugin version %s.", newPluginMetadata.Version, existingPluginMetadata.Version)}
 			case comp == 0:
-				return nil, nil, ErrInstallEqualVersion
+				return nil, nil, ErrInstallEqualVersion{Msg: fmt.Sprintf("Plugin %s with version %s already exists.", pluginName, existingPluginMetadata.Version)}
 			}
 		}
 	}

plugin/manager_test.go

@@ -221,8 +221,9 @@ func TestManager_Install(t *testing.T) {
 			newPluginStdout:       metadataJSON(validMetadata),
 		}
 		_, _, err = mgr.Install(context.Background(), newPluginFilePath, false)
-		if err == nil || err.Error() != ErrInstallEqualVersion.Error() {
-			t.Fatalf("expecting error %v, but got %v", ErrInstallEqualVersion, err)
+		expectedErrorMsg := "Plugin foo with version 1.0.0 already exists."
+		if err == nil || err.Error() != expectedErrorMsg {
+			t.Fatalf("expecting error %s, but got %v", expectedErrorMsg, err)
 		}
 	})
 
@@ -234,8 +235,9 @@ func TestManager_Install(t *testing.T) {
 			newPluginStdout:       metadataJSON(validMetadataLowerVersion),
 		}
 		_, _, err = mgr.Install(context.Background(), newPluginFilePath, false)
-		if err == nil || err.Error() != ErrInstallLowerVersion.Error() {
-			t.Fatalf("expecting error %v, but got %v", ErrInstallLowerVersion, err)
+		expectedErrorMsg := "The installing plugin version 0.1.0 is lower than the existing plugin version 1.0.0."
+		if err == nil || err.Error() != expectedErrorMsg {
+			t.Fatalf("expecting error %s, but got %v", expectedErrorMsg, err)
 		}
 	})