Update UserIndicators with newer implementation from Element (modified to work here)

UnitTests/Sources/UserIndicators/UserIndicatorQueueTests.swift

@@ -0,0 +1,56 @@
+// 
+// Copyright 2021 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+import XCTest
+@testable import ElementX
+
+class UserIndicatorQueueTests: XCTestCase {
+    var indicators: [UserIndicator]!
+    var queue: UserIndicatorQueue!
+    
+    override func setUp() {
+        indicators = []
+        queue = UserIndicatorQueue()
+    }
+    
+    func makeRequest() -> UserIndicatorRequest {
+        return UserIndicatorRequest(
+            presenter: UserIndicatorPresenterSpy(),
+            dismissal: .manual
+        )
+    }
+    
+    func testStartsIndicatorWhenAdded() {
+        let indicator = queue.add(makeRequest())
+        XCTAssertEqual(indicator.state, .executing)
+    }
+    
+    func testSecondIndicatorIsPending() {
+        queue.add(makeRequest()).store(in: &indicators)
+        let indicator = queue.add(makeRequest())
+        XCTAssertEqual(indicator.state, .pending)
+    }
+    
+    func testSecondIndicatorIsExecutingWhenFirstCompleted() {
+        let first = queue.add(makeRequest())
+        let second = queue.add(makeRequest())
+        
+        first.cancel()
+        
+        XCTAssertEqual(second.state, .executing)
+    }
+}