From 1d0a8713a17145e7df64beafb1343222d90bd08b Mon Sep 17 00:00:00 2001
From: ZiZi <44972592+ZiZasaurus@users.noreply.github.com>
Date: Wed, 20 Apr 2022 13:35:07 -0400
Subject: [PATCH] Resolve issue where location value is declared after observer
 is notified (#1287)

* declaring value before observer is notified and adding tests
---
 Sources/MapboxMaps/Foundation/ObservableValue.swift    |  2 +-
 .../Viewport/Helpers/ObservableValueTests.swift        | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Sources/MapboxMaps/Foundation/ObservableValue.swift b/Sources/MapboxMaps/Foundation/ObservableValue.swift
index 7131ac89f975..a62274111267 100644
--- a/Sources/MapboxMaps/Foundation/ObservableValue.swift
+++ b/Sources/MapboxMaps/Foundation/ObservableValue.swift
@@ -15,10 +15,10 @@ internal final class ObservableValue<Value> where Value: Equatable {
         guard newValue != value else {
             return
         }
+        value = newValue
         observers.forEach { (observer) in
             observer.invokeHandler(with: newValue)
         }
-        value = newValue
     }
 
     internal func observe(with handler: @escaping (Value) -> Bool) -> Cancelable {
diff --git a/Tests/MapboxMapsTests/Viewport/Helpers/ObservableValueTests.swift b/Tests/MapboxMapsTests/Viewport/Helpers/ObservableValueTests.swift
index 4b2e988276e0..73b80a443270 100644
--- a/Tests/MapboxMapsTests/Viewport/Helpers/ObservableValueTests.swift
+++ b/Tests/MapboxMapsTests/Viewport/Helpers/ObservableValueTests.swift
@@ -56,6 +56,16 @@ final class ObservableValueTests: XCTestCase {
         XCTAssertEqual(handlerStub.invocations.map(\.parameters), [value])
     }
 
+    func testValueUpdatedBeforeNotifyingObservers() {
+        let handlerStub = Stub<Int, Bool>(defaultReturnValue: true)
+        handlerStub.defaultSideEffect = { invocation in
+            XCTAssertEqual(self.observableValue.value, invocation.parameters)
+        }
+        _ = observableValue.observe(with: handlerStub.call(with:))
+
+        update()
+    }
+
     func testHandlerReturnsTrueToContinueAndFalseToUnsubscribe() {
         let handlerStub = Stub<Int, Bool>(defaultReturnValue: false)
         handlerStub.returnValueQueue = [true, true]