On core uninstall consider unversioned args as the installed, not the latest

Otherwise the command

  arduino-cli core unistall arduino:avr

will fail with:

  arduino:[email protected] is not installed

if the installed core it's an earlier version than 1.6.20

Author: cmaglie

commands/commands_test.go

@@ -355,15 +355,20 @@ func TestCoreCommands(t *testing.T) {
 	require.Zero(t, exitCode, "exit code")
 	require.Empty(t, strings.TrimSpace(string(d)))
 
-	// Install avr
-	exitCode, d = executeWithArgs(t, "core", "install", "arduino:avr")
+	// Install avr 1.6.16
+	exitCode, d = executeWithArgs(t, "core", "install", "arduino:avr@1.6.16")
 	require.Zero(t, exitCode, "exit code")
-	require.Contains(t, string(d), AVR+" installed")
+	require.Contains(t, string(d), "arduino:[email protected] installed")
 
 	exitCode, d = executeWithArgs(t, "core", "list")
 	require.Zero(t, exitCode, "exit code")
 	require.Contains(t, string(d), "arduino:avr")
 
+	// List updatable cores
+	exitCode, d = executeWithArgs(t, "core", "list", "--updatable")
+	require.Zero(t, exitCode, "exit code")
+	require.Contains(t, string(d), "arduino:avr")
+
 	// Build sketch for arduino:avr:uno
 	exitCode, d = executeWithArgs(t, "sketch", "new", "Test1")
 	require.Zero(t, exitCode, "exit code")
@@ -376,7 +381,7 @@ func TestCoreCommands(t *testing.T) {
 	// Uninstall arduino:avr
 	exitCode, d = executeWithArgs(t, "core", "uninstall", "arduino:avr")
 	require.Zero(t, exitCode, "exit code")
-	require.Contains(t, string(d), AVR+" uninstalled")
+	require.Contains(t, string(d), "arduino:[email protected] uninstalled")
 
 	// Empty cores list
 	exitCode, d = executeWithArgs(t, "core", "list")

commands/core/uninstall.go

@@ -52,6 +52,21 @@ func runUninstallCommand(cmd *cobra.Command, args []string) {
 }
 
 func uninstallPlatformByRef(pm *packagemanager.PackageManager, platformRef *packagemanager.PlatformReference) {
+	// If no version is specified consider the installed
+	if platformRef.PlatformVersion == nil {
+		platform := pm.FindPlatform(platformRef)
+		if platform == nil {
+			formatter.PrintErrorMessage("Platform not found " + platformRef.String())
+			os.Exit(commands.ErrBadCall)
+		}
+		platformRelease := platform.GetInstalled()
+		if platformRelease == nil {
+			formatter.PrintErrorMessage("Platform not installed " + platformRef.String())
+			os.Exit(commands.ErrBadCall)
+		}
+		platformRef.PlatformVersion = platformRelease.Version
+	}
+
 	platform, tools, err := pm.FindPlatformReleaseDependencies(platformRef)
 	if err != nil {
 		formatter.PrintError(err, "Could not determine platform dependencies")