test(RemoteConfig): keep late callbacks from crashing APITests

APITests and FakeConsoleTests read `self.config` inside fetch and activate completion handlers, but APITestBase.tearDown() sets `config` to nil. When a test times out, its activate completion can still run later, unwrap nil, and crash the test process. On the visionOS CI jobs this turned three expectation timeouts into a crash and a test-runner restart. Capture a local strong reference to `config` at the start of each test and use it in the handlers, so a late handler runs against a valid instance instead of crashing. Document the pattern on APITestBase.config.
paulb777 · Oct 5, 2026 · Oct 2, 2026 · Oct 2, 2026 · 3b24b0968497224e4450b40b7c0cc586e13af55d
commit 3b24b0968497224e4450b40b7c0cc586e13af55d
diff --git a/FirebaseRemoteConfig/Tests/Swift/FakeConsole/FakeConsoleTests.swift b/FirebaseRemoteConfig/Tests/Swift/FakeConsole/FakeConsoleTests.swift
@@ -26,16 +26,17 @@
   // Test New API.
   // Contrast with testUnchangedActivateWillFlag in APITests.swift.
   func testChangedActivateWillNotFlag() {
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
     config.fetch { status, error in
       if let error {
         XCTFail("Fetch Error \(error)")
       }
       XCTAssertEqual(status, RemoteConfigFetchStatus.success)
-      self.config.activate { changed, error in
+      config.activate { changed, error in
         XCTAssertNil(error)
         XCTAssertTrue(changed)
-        XCTAssertEqual(self.config["Key1"].stringValue, "Value1")
+        XCTAssertEqual(config["Key1"].stringValue, "Value1")
         expectation.fulfill()
       }
     }
@@ -50,10 +51,10 @@
         XCTFail("Fetch Error \(error)")
       }
       XCTAssertEqual(status, RemoteConfigFetchStatus.success)
-      self.config.activate { changed, error in
+      config.activate { changed, error in
         XCTAssertNil(error)
         XCTAssert(changed)
-        XCTAssertEqual(self.config["Key1"].stringValue, "Value2")
+        XCTAssertEqual(config["Key1"].stringValue, "Value2")
         expectation2.fulfill()
       }
     }
@@ -62,7 +63,7 @@

  private func waitForExpectations() {
    let kFIRStorageIntegrationTestTimeout = 10.0
    waitForExpectations(timeout: kFIRStorageIntegrationTestTimeout,
                        handler: { error in
                          if let error {
                            print(error)

diff --git a/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITestBase.swift b/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITestBase.swift
@@ -26,6 +26,9 @@ class APITestBase: XCTestCase {
   static var mockedFetch: Bool!
   static var mockedRealtime: Bool!
   var app: FirebaseApp!
+  /// Reset to `nil` in `tearDown()`. A completion handler can still run after its test times out,
+  /// so handlers should use a local reference captured at the start of the test instead of
+  /// reading `self.config`.
   var config: RemoteConfig!
   var console: RemoteConfigConsole!
   var fakeConsole: FakeConsole!

diff --git a/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITests.swift b/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITests.swift
@@ -19,45 +19,48 @@
 
 class APITests: APITestBase {
   func testFetchThenActivate() {
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
     config.fetch { status, error in
       if let error {
         XCTFail("Fetch Error \(error)")
       }
       XCTAssertEqual(status, RemoteConfigFetchStatus.success)
-      self.config.activate { _, error in
+      config.activate { _, error in
         XCTAssertNil(error)
-        XCTAssertEqual(self.config[Constants.key1].stringValue, Constants.value1)
+        XCTAssertEqual(config[Constants.key1].stringValue, Constants.value1)
         expectation.fulfill()
       }
     }
     waitForExpectations()
   }
 
   func testFetchWithExpirationThenActivate() {
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
     config.fetch(withExpirationDuration: 0) { status, error in
       if let error {
         XCTFail("Fetch Error \(error)")
       }
       XCTAssertEqual(status, RemoteConfigFetchStatus.success)
-      self.config.activate { _, error in
+      config.activate { _, error in
         XCTAssertNil(error)
-        XCTAssertEqual(self.config[Constants.key1].stringValue, Constants.value1)
+        XCTAssertEqual(config[Constants.key1].stringValue, Constants.value1)
         expectation.fulfill()
       }
     }
     waitForExpectations()
   }
 
   func testFetchAndActivate() {
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
     config.fetchAndActivate { status, error in
       XCTAssertEqual(status, .successFetchedFromRemote)
       if let error {
         XCTFail("Fetch and Activate Error \(error)")
       }
-      XCTAssertEqual(self.config[Constants.key1].stringValue, Constants.value1)
+      XCTAssertEqual(config[Constants.key1].stringValue, Constants.value1)
       expectation.fulfill()
     }
     waitForExpectations()
@@ -66,16 +69,17 @@
   // Test New API.
   // Contrast with testChangedActivateWillNotFlag in FakeConsole.swift.
   func testUnchangedActivateWillFlag() {
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
     config.fetch { status, error in
       if let error {
         XCTFail("Fetch Error \(error)")
       }
       XCTAssertEqual(status, RemoteConfigFetchStatus.success)
-      self.config.activate { changed, error in
+      config.activate { changed, error in
         XCTAssertTrue(!APITests.useFakeConfig || changed)
         XCTAssertNil(error)
-        XCTAssertEqual(self.config[Constants.key1].stringValue, Constants.value1)
+        XCTAssertEqual(config[Constants.key1].stringValue, Constants.value1)
         expectation.fulfill()
       }
     }
@@ -86,10 +90,10 @@
         XCTFail("Fetch Error \(error)")
       }
       XCTAssertEqual(status, RemoteConfigFetchStatus.success)
-      self.config.activate { changed, error in
+      config.activate { changed, error in
         XCTAssertFalse(changed)
         XCTAssertNil(error)
-        XCTAssertEqual(self.config[Constants.key1].stringValue, Constants.value1)
+        XCTAssertEqual(config[Constants.key1].stringValue, Constants.value1)
         expectation2.fulfill()
       }
     }
@@ -99,6 +103,7 @@
   func testFetchAndActivateUnchangedConfig() throws {
     guard APITests.useFakeConfig == false else { return }
 
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
 
     XCTAssertEqual(config.settings.minimumFetchInterval, 0)
@@ -108,7 +113,7 @@
     group.enter()
     serialQueue.async {
       // Represents pre-fetch occurring sometime in past.
-      self.config.fetch { status, error in
+      config.fetch { status, error in
         XCTAssertNil(error, "Fetch Error \(error!)")
         XCTAssertEqual(status, .success)
         group.leave()
@@ -119,7 +124,7 @@
       group.wait()
       group.enter()
       // Represents a `fetchAndActivate` being made to pull latest changes from Remote Config.
-      self.config.fetchAndActivate { status, error in
+      config.fetchAndActivate { status, error in
         XCTAssertNil(error, "Fetch & Activate Error \(error!)")
         // Since no updates to remote config have occurred we use the `.successUsingPreFetchedData`.
         // The behavior of the next test changed in Firebase 7.0.0.
@@ -129,8 +134,8 @@
         // XCTAssertEqual(status, .successUsingPreFetchedData)
         XCTAssertEqual(status, .successFetchedFromRemote)
         // The `lastETagUpdateTime` should either be older or the same time as `lastFetchTime`.
-        if let lastFetchTime = try? XCTUnwrap(self.config.lastFetchTime) {
-          XCTAssertLessThanOrEqual(Double(self.config.settings.lastETagUpdateTime),
+        if let lastFetchTime = try? XCTUnwrap(config.lastFetchTime) {
+          XCTAssertLessThanOrEqual(Double(config.settings.lastETagUpdateTime),
                                    Double(lastFetchTime.timeIntervalSince1970))
         } else {
           XCTFail("Could not unwrap lastFetchTime.")
@@ -184,11 +189,12 @@
   func testFetchConfigThenUpdateConsoleThenFetchAgain() {
     guard APITests.useFakeConfig == false else { return }
 
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
 
     config.fetchAndActivate { status, error in
       XCTAssertNil(error, "Fetch & Activate Error \(error!)")
-      XCTAssertEqual(self.config.configValue(forKey: Constants.jedi).stringValue, Constants.obiwan)
+      XCTAssertEqual(config.configValue(forKey: Constants.jedi).stringValue, Constants.obiwan)
       expectation.fulfill()
     }
     waitForExpectations()
@@ -199,7 +205,7 @@
     let expectation2 = self.expectation(description: #function + "2")
     config.fetchAndActivate { status, error in
       XCTAssertNil(error, "Fetch & Activate Error \(error!)")
-      XCTAssertEqual(self.config.configValue(forKey: Constants.jedi).stringValue, Constants.yoda)
+      XCTAssertEqual(config.configValue(forKey: Constants.jedi).stringValue, Constants.yoda)
       expectation2.fulfill()
     }
     waitForExpectations()
@@ -208,13 +214,14 @@
   func testFetchConfigThenAddValueOnConsoleThenFetchAgain() {
     guard APITests.useFakeConfig == false else { return }
 
+    let config: RemoteConfig = self.config
     // Ensure no Sith Lord has been written to Remote Config yet.
     let expectation = self.expectation(description: #function)
 
     config.fetchAndActivate { status, error in
       XCTAssertNil(error, "Fetch & Activate Error \(error!)")
 
-      XCTAssertTrue(self.config.configValue(forKey: Constants.sith).dataValue.isEmpty)
+      XCTAssertTrue(config.configValue(forKey: Constants.sith).dataValue.isEmpty)
 
       expectation.fulfill()
     }
@@ -229,7 +236,7 @@
     config.fetchAndActivate { status, error in
       XCTAssertNil(error, "Fetch & Activate Error \(error!)")
       XCTAssertEqual(
-        self.config.configValue(forKey: Constants.sith).stringValue,
+        config.configValue(forKey: Constants.sith).stringValue,
         Constants.darthSidious
       )
       expectation2.fulfill()
@@ -240,11 +247,12 @@
   func testFetchConfigThenDeleteValueOnConsoleThenFetchAgain() {
     guard APITests.useFakeConfig == false else { return }
 
+    let config: RemoteConfig = self.config
     let expectation = self.expectation(description: #function)
 
     config.fetchAndActivate { status, error in
       XCTAssertNil(error, "Fetch & Activate Error \(error!)")
-      XCTAssertEqual(self.config.configValue(forKey: Constants.jedi).stringValue, Constants.obiwan)
+      XCTAssertEqual(config.configValue(forKey: Constants.jedi).stringValue, Constants.obiwan)
       expectation.fulfill()
     }
     waitForExpectations()
@@ -256,7 +264,7 @@
     config.fetchAndActivate { status, error in
       XCTAssertNil(error, "Fetch & Activate Error \(error!)")
 
-      XCTAssertTrue(self.config.configValue(forKey: Constants.jedi).dataValue.isEmpty,
+      XCTAssertTrue(config.configValue(forKey: Constants.jedi).dataValue.isEmpty,
                     "Remote config should have been deleted.")
 
       expectation2.fulfill()
@@ -268,7 +276,7 @@

  private func waitForExpectations() {
    let kTestTimeout = 10.0
    waitForExpectations(timeout: kTestTimeout,
                        handler: { error in
                          if let error {
                            print(error)