Adding changes to separate unit tests and integration tests (#13670)

* Introducing unit (not integration) tests for the app layer

* Initial support for unit tests at the API

* Adding unit tests support to the store layer

* Add unit tests support in commands

* Adding last tests needed for run unit tests properly

* Fixing govet

* Removing some duplication

* Fixing tests

* Fixing tests

* Not compiling test helpers with the main module for api

* Revert "Not compiling test helpers with the main module for api"

This reverts commit 36a199bbe0f7503f665f5d6c7b41c53aabc2e54f.

* Fixing tests

* Fixing unit tests

* More consistency between api4/apiteslib.go and app/helper_test.go

* Renaming things to make more obvious the new Setup functions purpose

* Reverting change in go.sum

* Start with empty mock for app layer

* Start with empty mock for api layer

* Start with empty mock for web layer

* Renaming SetupWithStoreMockConfig to SetupConfigWithStoreMock

* Fixing tests on web package

* Removing unnecesary function

cmd/mattermost/commands/cmdtestlib.go

@@ -57,6 +57,28 @@ func Setup(t testing.TB) *testHelper {
 	return testHelper
 }
 
+// Setup creates an instance of testHelper.
+func SetupWithStoreMock(t testing.TB) *testHelper {
+	dir, err := ioutil.TempDir("", "testHelper")
+	if err != nil {
+		panic("failed to create temporary directory: " + err.Error())
+	}
+
+	api4TestHelper := api4.SetupWithStoreMock(t)
+
+	testHelper := &testHelper{
+		TestHelper:     api4TestHelper,
+		tempDir:        dir,
+		configFilePath: filepath.Join(dir, "config-helper.json"),
+	}
+
+	config := &model.Config{}
+	config.SetDefaults()
+	testHelper.SetConfig(config)
+
+	return testHelper
+}
+
 // InitBasic simply proxies to api4.InitBasic, while still returning a testHelper.
 func (h *testHelper) InitBasic() *testHelper {
 	h.TestHelper.InitBasic()
@@ -80,7 +102,9 @@ func (h *testHelper) ConfigPath() string {
 
 // SetConfig replaces the configuration passed to a running command.
 func (h *testHelper) SetConfig(config *model.Config) {
-	config.SqlSettings = *mainHelper.GetSQLSettings()
+	if !testing.Short() {
+		config.SqlSettings = *mainHelper.GetSQLSettings()
+	}
 
 	// Disable strict password requirements for test
 	*config.PasswordSettings.MinimumLength = 5