PLT-6113 Added initial unit tests for cmd package (#6086)

* Fixed app.CreateUser not using the provided locale

* Added initial unit tests for cmd package

* Disabled unit tests while we move to 'go build'

cmd/platform/cmdtestlib.go

@@ -0,0 +1,45 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package main
+
+import (
+	"bytes"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+func runCommand(argString string) error {
+	err, _ := runCommandWithOutput(argString)
+
+	return err
+}
+
+func runCommandWithOutput(argString string) (error, string) {
+	// Set arguments on the root command
+	rootCmd.SetArgs(strings.Split(argString, " "))
+	defer rootCmd.SetArgs([]string{})
+
+	output := new(bytes.Buffer)
+	rootCmd.SetOutput(output)
+	defer rootCmd.SetOutput(nil)
+
+	// Executing the root command will call the necessary subcommand
+	cmd, err := rootCmd.ExecuteC()
+
+	// And clear the arguments on the subcommand that was actually called since they'd otherwise
+	// be used on the next call to this command
+	clearArgs(cmd)
+
+	return err, output.String()
+}
+
+func clearArgs(command *cobra.Command) {
+	command.Flags().VisitAll(clearFlag)
+}
+
+func clearFlag(flag *pflag.Flag) {
+	flag.Value.Set(flag.DefValue)
+}