Added test for arduino#1529

Author: cmaglie

Diff for: internal/integrationtest/arduino-cli.go

@@ -458,3 +458,11 @@ func (inst *ArduinoCLIInstance) UpdateIndex(ctx context.Context, ignoreCustomPac
 	logCallf(">>> UpdateIndex(%+v)\n", req)
 	return updCl, err
 }
+
+// PlatformList calls the "PlatformList" gRPC method.
+func (inst *ArduinoCLIInstance) PlatformList(ctx context.Context) (*commands.PlatformListResponse, error) {
+	req := &commands.PlatformListRequest{Instance: inst.instance}
+	logCallf(">>> PlatformList(%+v)\n", req)
+	resp, err := inst.cli.daemonClient.PlatformList(ctx, req)
+	return resp, err
+}

Diff for: internal/integrationtest/daemon/daemon_test.go

@@ -81,6 +81,23 @@ func TestArduinoCliDaemon(t *testing.T) {
 	testWatcher()
 }
 
+func TestDaemonAutoUpdateIndexOnFirstInit(t *testing.T) {
+	// https://github.com/arduino/arduino-cli/issues/1529
+
+	env, cli := createEnvForDaemon(t)
+	defer env.CleanUp()
+
+	grpcInst := cli.Create()
+	require.NoError(t, grpcInst.Init("", "", func(ir *commands.InitResponse) {
+		fmt.Printf("INIT> %v\n", ir.GetMessage())
+	}))
+
+	_, err := grpcInst.PlatformList(context.Background())
+	require.NoError(t, err)
+
+	require.FileExists(t, cli.DataDir().Join("package_index.json").String())
+}
+
 // createEnvForDaemon performs the minimum required operations to start the arduino-cli daemon.
 // It returns a testsuite.Environment and an ArduinoCLI client to perform the integration tests.
 // The Environment must be disposed by calling the CleanUp method via defer.