Improve test coverage reporting / accuracy (#7819)

* improve test coverage reporting / accuracy

* handle absolute coverpaths

* move tests into multiple files

* rename codecov.yml (https://github.com/codecov/support/issues/426)

cmd/platform/roles_test.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package main
+
+import (
+	"testing"
+
+	"github.com/mattermost/mattermost-server/api"
+	"github.com/mattermost/mattermost-server/model"
+)
+
+func TestAssignRole(t *testing.T) {
+	th := api.Setup().InitBasic()
+	defer th.TearDown()
+
+	checkCommand(t, "roles", "system_admin", th.BasicUser.Email)
+
+	if result := <-th.App.Srv.Store.User().GetByEmail(th.BasicUser.Email); result.Err != nil {
+		t.Fatal()
+	} else {
+		user := result.Data.(*model.User)
+		if user.Roles != "system_admin system_user" {
+			t.Fatal()
+		}
+	}
+}