fix flaky test (#8989)

This PR addresses flakiness(likely caused by network) with
`testLoadStyleHandlerIsInvokedExactlyOnce` test. Looking at the test I'm
not sure what scenario is being tested, as with adoption of runtime
styling callbacks `onStyleLoaded` event has nothing to do with style
loaded completion invocation.
I replaced the test with more fitting test for current setup. In the
test I issue two style load requests one after another - my expectation
is that the completion handler is invoked once per subscriber.

cc @mapbox/maps-ios

GitOrigin-RevId: 16f46a5e0ce4a58f1313526347bafd164a242123

Author: evil159

Tests/MapboxMapsTests/Foundation/MapboxMapTests.swift

@@ -369,22 +369,24 @@ final class MapboxMapTests: XCTestCase {
         XCTAssertEqual(mapboxMap.__testingMap.getCenterAltitudeMode(), .sea)
     }
 
-    func testLoadStyleHandlerIsInvokedExactlyOnce() throws {
-        let completionIsCalledOnce = expectation(description: "loadStyle completion should be called once")
+    func testLoadStyle() throws {
+        let completionIsCalledOncePerSubscriber = expectation(
+            description: "loadStyle completion should be called once per subscriber"
+        )
+        completionIsCalledOncePerSubscriber.expectedFulfillmentCount = 2
+        let styleJSON = String.testStyleJSON()
 
+        // this load should be cancelled to the succeeding load,
+        // but the completion is expected to be invoked after successfull style load
         mapboxMap.loadStyle(.dark) { _ in
-            completionIsCalledOnce.fulfill()
+            completionIsCalledOncePerSubscriber.fulfill()
         }
-
-        // Ensure loadStyle subscription is registered before firing events
-        // by dispatching event sends asynchronously on the main queue
-        let interval = EventTimeInterval(begin: .init(), end: .init())
-        DispatchQueue.main.async {
-            self.events.onStyleLoaded.send(StyleLoaded(timeInterval: interval))
-            self.events.onStyleLoaded.send(StyleLoaded(timeInterval: interval))
+        mapboxMap.loadStyle(styleJSON) { _ in
+            completionIsCalledOncePerSubscriber.fulfill()
         }
+        XCTAssertEqual(mapboxMap.styleJSON, styleJSON)
 
-        waitForExpectations(timeout: 5.0)
+        waitForExpectations(timeout: 3.0)
     }
 
     func testEvents() {

Tests/MapboxMapsTests/Style/Fixtures/Fixtures.swift

@@ -157,8 +157,8 @@ internal extension String {
                  41.8781
             ],
             "zoom": 12,
-            "sources": [Any](),
-            "layers": [Any]()
+            "sources": [String: Any](),
+            "layers": [String: Any]()
         ]
         return ValueConverter.toJson(forValue: styleJSONObject)
     }