Write tests for the new Mongo query function (#1314)

* WIP: Added tests to query implemetation.

* Fixed tests for mongo getter query function.

pkg/storage/mongo/mongo_test.go

@@ -1,12 +1,17 @@
 package mongo
 
 import (
+	"bytes"
 	"context"
+	"io/ioutil"
 	"os"
 	"testing"
 
 	"github.com/gomods/athens/pkg/config"
+	"github.com/gomods/athens/pkg/errors"
+	"github.com/gomods/athens/pkg/storage"
 	"github.com/gomods/athens/pkg/storage/compliance"
+
 	"github.com/stretchr/testify/require"
 )
 
@@ -38,6 +43,60 @@ func getStorage(tb testing.TB) *ModuleStore {
 	return backend
 }
 
+func TestQueryModuleVersionExists(t *testing.T) {
+	modname, ver := "getTestModule", "v1.2.3"
+	mock := &storage.Version{
+		Info: []byte("123"),
+		Mod:  []byte("456"),
+		Zip:  ioutil.NopCloser(bytes.NewReader([]byte("789"))),
+	}
+
+	ctx := context.Background()
+	backend := getStorage(t)
+
+	zipBts, _ := ioutil.ReadAll(mock.Zip)
+	backend.Save(ctx, modname, ver, mock.Mod, bytes.NewReader(zipBts), mock.Info)
+	defer backend.Delete(ctx, modname, ver)
+
+	info, err := query(ctx, backend, modname, ver)
+	require.NoError(t, err)
+	require.Equal(t, mock.Info, info.Info)
+	require.Equal(t, mock.Mod, info.Mod)
+}
+
+func TestQueryKindNotFoundErrorCases(t *testing.T) {
+	modname, ver := "getTestModule", "v1.2.3"
+	mock := &storage.Version{
+		Info: []byte("123"),
+		Mod:  []byte("456"),
+		Zip:  ioutil.NopCloser(bytes.NewReader([]byte("789"))),
+	}
+
+	ctx := context.Background()
+	backend := getStorage(t)
+
+	zipBts, _ := ioutil.ReadAll(mock.Zip)
+	backend.Save(ctx, modname, ver, mock.Mod, bytes.NewReader(zipBts), mock.Info)
+	defer backend.Delete(ctx, modname, ver)
+
+	testCases := []struct {
+		modname string
+		ver     string
+	}{
+		{"getTestModule", "yyy"}, // test NotFound non-existent version
+		{"getTestModule", ""},    // test NotFound empty str version
+		{"xxx", "v1.2.3"},        // test NotFound non-existent module
+		{"", "v1.2.3"},           // test NotFound empty str module
+		{"", ""},                 // test NotFound empty str module and version
+		{"xxx", "yyy"},           // test NotFound non-existent module and version
+	}
+
+	for _, test := range testCases {
+		_, err := query(ctx, backend, test.modname, test.ver)
+		require.Error(t, err)
+		require.Equal(t, errors.KindNotFound, errors.Kind(err))
+	}
+}
 func TestNewStorageWithDefaultOverrides(t *testing.T) {
 	url := os.Getenv("ATHENS_MONGO_STORAGE_URL")