report and catch a specific error when already installed

arduino/libraries/librariesmanager/install.go

@@ -18,6 +18,7 @@
 package librariesmanager
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/arduino/arduino-cli/arduino/libraries"
@@ -26,18 +27,26 @@ import (
 	paths "github.com/arduino/go-paths-helper"
 )
 
+var (
+	// ErrAlreadyInstalled is returned when a library is already installed and task
+	// cannot proceed.
+	ErrAlreadyInstalled = errors.New("library already installed")
+)
+
 // InstallPrerequisiteCheck performs prequisite checks to install a library. It returns the
 // install path, where the library should be installed and the possible library that is already
 // installed on the same folder and it's going to be replaced by the new one.
 func (lm *LibrariesManager) InstallPrerequisiteCheck(indexLibrary *librariesindex.Release) (*paths.Path, *libraries.Library, error) {
+	saneName := utils.SanitizeName(indexLibrary.Library.Name)
+
 	var replaced *libraries.Library
-	if installedLibs, have := lm.Libraries[indexLibrary.Library.Name]; have {
+	if installedLibs, have := lm.Libraries[saneName]; have {
 		for _, installedLib := range installedLibs.Alternatives {
 			if installedLib.Location != libraries.Sketchbook {
 				continue
 			}
 			if installedLib.Version.Equal(indexLibrary.Version) {
-				return installedLib.InstallDir, nil, fmt.Errorf("%s is already installed", indexLibrary.String())
+				return installedLib.InstallDir, nil, ErrAlreadyInstalled
 			}
 			replaced = installedLib
 		}
@@ -48,7 +57,7 @@ func (lm *LibrariesManager) InstallPrerequisiteCheck(indexLibrary *librariesinde
 		return nil, nil, fmt.Errorf("sketchbook directory not set")
 	}
 
-	libPath := libsDir.Join(utils.SanitizeName(indexLibrary.Library.Name))
+	libPath := libsDir.Join(saneName)
 	if replaced != nil && replaced.InstallDir.EquivalentTo(libPath) {
 
 	} else if libPath.IsDir() {

commands/lib/install.go

@@ -58,16 +58,23 @@ func installLibrary(lm *librariesmanager.LibrariesManager, libRelease *libraries
 	taskCB(&rpc.TaskProgress{Name: "Installing " + libRelease.String()})
 	logrus.WithField("library", libRelease).Info("Installing library")
 	libPath, libReplaced, err := lm.InstallPrerequisiteCheck(libRelease)
+	if err == librariesmanager.ErrAlreadyInstalled {
+		taskCB(&rpc.TaskProgress{Message: "Alredy installed " + libRelease.String(), Completed: true})
+		return nil
+	}
+
 	if err != nil {
 		return fmt.Errorf("checking lib install prerequisites: %s", err)
 	}
+
 	if libReplaced != nil {
 		taskCB(&rpc.TaskProgress{Message: fmt.Sprintf("Replacing %s with %s", libReplaced, libRelease)})
 	}
+
 	if err := lm.Install(libRelease, libPath); err != nil {
 		return err
 	}
-	taskCB(&rpc.TaskProgress{Message: "Installed " + libRelease.String(), Completed: true})
 
+	taskCB(&rpc.TaskProgress{Message: "Installed " + libRelease.String(), Completed: true})
 	return nil
 }