Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/utils/backoff_test.go

@@ -0,0 +1,65 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package utils
+
+import (
+	"testing"
+
+	"github.com/pkg/errors"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestProgressiveRetry(t *testing.T) {
+	var retries int
+
+	type args struct {
+		operation func() error
+	}
+	tests := []struct {
+		name            string
+		args            args
+		wantErr         bool
+		expectedRetries int
+	}{
+		{
+			name: "Should fail and return error",
+			args: args{
+				operation: func() error {
+					retries++
+					return errors.New("Operation Failed")
+				},
+			},
+			wantErr:         true,
+			expectedRetries: 6,
+		},
+		{
+			name: "Should succeed after two retries",
+			args: args{
+				operation: func() error {
+					retries++
+					if retries == 2 {
+						return nil
+					}
+
+					return errors.New("Operation Failed")
+				},
+			},
+			wantErr:         false,
+			expectedRetries: 2,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			retries = 0
+
+			err := ProgressiveRetry(tt.args.operation)
+			if !tt.wantErr {
+				require.NoError(t, err)
+			}
+
+			assert.Equal(t, tt.expectedRetries, retries)
+		})
+	}
+}