[XYZ-6] Add sampledata platform command (#8027)

* Add fake dependency

* [XYZ-6] Add sampledata platform command

* Creating EMOJI_NAME_MAX_LENGTH as a constant and using it where needed

cmd/platform/sampledata_test.go

@@ -0,0 +1,25 @@
+// 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/stretchr/testify/require"
+)
+
+func TestSampledataBadParameters(t *testing.T) {
+	th := api.Setup().InitBasic()
+	defer th.TearDown()
+
+	// should fail because you need at least 1 worker
+	require.Error(t, runCommand(t, "sampledata", "--workers", "0"))
+
+	// should fail because you have more team memberships than teams
+	require.Error(t, runCommand(t, "sampledata", "--teams", "10", "--teams-memberships", "11"))
+
+	// should fail because you have more channel memberships than channels per team
+	require.Error(t, runCommand(t, "sampledata", "--channels-per-team", "10", "--channel-memberships", "11"))
+}