test: add multi-key plugin registration test

- Add testPluginRegistrationWithMultipleKeys to verify plugin registration
- Test that plugins are registered once per mobile key (primary + secondary)
- Verify correct mobile key credentials are passed to each registration
- Ensure all client instances and metadata are properly created

Co-Authored-By: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

LaunchDarkly/LaunchDarklyTests/LDClientPluginsSpec.swift

@@ -35,6 +35,42 @@ final class LDClientPluginsSpec: XCTestCase {
         XCTAssertEqual(receivedMetadata?.sdkMetadata.name, ReportingConsts.sdkName)
     }
 
+    func testPluginRegistrationWithMultipleKeys() {
+        var registerCallCount = 0
+        var receivedClients: [LDClient] = []
+        var receivedMetadata: [EnvironmentMetadata] = []
+        
+        let mockPlugin = MockPlugin { client, metadata in
+            registerCallCount += 1
+            receivedClients.append(client)
+            receivedMetadata.append(metadata)
+        }
+        
+        var config = LDConfig(mobileKey: "primary-mobile-key", autoEnvAttributes: .disabled)
+        try! config.setSecondaryMobileKeys(["test": "secondary-key-1", "debug": "secondary-key-2"])
+        config.plugins = [mockPlugin]
+        
+        var testContext: TestContext!
+        waitUntil { done in
+            testContext = TestContext(newConfig: config)
+            testContext.start(completion: done)
+        }
+        
+        XCTAssertEqual(registerCallCount, 3)
+        
+        XCTAssertEqual(receivedClients.count, 3)
+        XCTAssertEqual(receivedMetadata.count, 3)
+        
+        let credentials = receivedMetadata.map { $0.credential }
+        XCTAssertTrue(credentials.contains("primary-mobile-key"))
+        XCTAssertTrue(credentials.contains("secondary-key-1"))
+        XCTAssertTrue(credentials.contains("secondary-key-2"))
+        
+        for metadata in receivedMetadata {
+            XCTAssertEqual(metadata.sdkMetadata.name, ReportingConsts.sdkName)
+        }
+    }
+    
     class MockPlugin: Plugin {
         private let registerCallback: (LDClient, EnvironmentMetadata) -> Void