Add test for plugin service

plugin/service_test.go

@@ -0,0 +1,45 @@
+package plugin_test
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/NethermindEth/juno/mocks"
+	"github.com/NethermindEth/juno/plugin"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/mock/gomock"
+)
+
+func TestService(t *testing.T) {
+	t.Run("shutdown ok", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+
+		p := mocks.NewMockJunoPlugin(ctrl)
+		p.EXPECT().Shutdown().Return(nil)
+		service := plugin.NewService(p)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+		// after ^ this ctx already cancelled
+
+		err := service.Run(ctx)
+		require.NoError(t, err)
+	})
+	t.Run("shutdown with error", func(t *testing.T) {
+		ctrl := gomock.NewController(t)
+
+		shutdownErr := errors.New("error during shutdown")
+
+		p := mocks.NewMockJunoPlugin(ctrl)
+		p.EXPECT().Shutdown().Return(shutdownErr)
+		service := plugin.NewService(p)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+		// after ^ this ctx already cancelled
+
+		err := service.Run(ctx)
+		require.Equal(t, shutdownErr, err)
+	})
+}