- UnitTests: Added unitttests for new datastructures - LinkedHashMap and TreeMap

2026-02-09 06:43:25 +01:00 · 2025-02-21 19:04:40 +05:30
parent 08e11eece4
commit 15f4ae7b5a
4 changed files with 400 additions and 2 deletions
--- a/AltStore.xcodeproj/project.pbxproj
+++ b/AltStore.xcodeproj/project.pbxproj
@@ -59,12 +59,18 @@
 		A80D60D32D3DD85100CEF65D /* ReleaseTrack.swift in Sources */ = {isa = PBXBuildFile; fileRef = A80D60D12D3D705F00CEF65D /* ReleaseTrack.swift */; };
 		A80D790D2D2F20AF00A40F40 /* PaginationIntent.swift in Sources */ = {isa = PBXBuildFile; fileRef = A80D790C2D2F20AF00A40F40 /* PaginationIntent.swift */; };
 		A80D790F2D2F217000A40F40 /* PaginationDataHolder.swift in Sources */ = {isa = PBXBuildFile; fileRef = A80D790E2D2F217000A40F40 /* PaginationDataHolder.swift */; };
+		A81A8CB52D68B2180086C96F /* TreeMapTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A81A8CB42D68B2180086C96F /* TreeMapTests.swift */; };
+		A81A8CB92D68B30B0086C96F /* SingletonGenericMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A868CFE32D319988002F1201 /* SingletonGenericMap.swift */; };
+		A81A8CBA2D68B3110086C96F /* TreeMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A81A8CB02D68B0320086C96F /* TreeMap.swift */; };
+		A81A8CBB2D68B3230086C96F /* TreeMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A81A8CB02D68B0320086C96F /* TreeMap.swift */; };
+		A81A8CBD2D68B43F0086C96F /* LinkedHashMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A81A8CBC2D68B43F0086C96F /* LinkedHashMap.swift */; };
+		A81A8CBE2D68B43F0086C96F /* LinkedHashMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A81A8CBC2D68B43F0086C96F /* LinkedHashMap.swift */; };
+		A81A8CC02D68B4520086C96F /* LinkedHashMapTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = A81A8CBF2D68B4520086C96F /* LinkedHashMapTests.swift */; };
 		A82067842D03DC0600645C0D /* OperatingSystemVersion+Comparable.swift in Sources */ = {isa = PBXBuildFile; fileRef = D5708416292448DA00D42D34 /* OperatingSystemVersion+Comparable.swift */; };
 		A82067C42D03E0DE00645C0D /* SemanticVersion in Frameworks */ = {isa = PBXBuildFile; productRef = A82067C32D03E0DE00645C0D /* SemanticVersion */; };
 		A859ED5C2D1EE827003DCC58 /* OpenSSL.xcframework in Frameworks */ = {isa = PBXBuildFile; fileRef = A859ED5B2D1EE80D003DCC58 /* OpenSSL.xcframework */; };
 		A859ED5D2D1EE827003DCC58 /* OpenSSL.xcframework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = A859ED5B2D1EE80D003DCC58 /* OpenSSL.xcframework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
 		A86315DF2D3EB2DE0048FA40 /* ErrorProcessing.swift in Sources */ = {isa = PBXBuildFile; fileRef = A86315DE2D3EB2D80048FA40 /* ErrorProcessing.swift */; };
-		A868CFE42D31999A002F1201 /* SingletonGenericMap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A868CFE32D319988002F1201 /* SingletonGenericMap.swift */; };
 		A8696EE42D34512C00E96389 /* RemoveAppExtensionsOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = A8696EE32D34512C00E96389 /* RemoveAppExtensionsOperation.swift */; };
 		A88B8C492D35AD3200F53F9D /* OperationsLoggingContolView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A88B8C482D35AD3200F53F9D /* OperationsLoggingContolView.swift */; };
 		A88B8C552D35F1EC00F53F9D /* OperationsLoggingControl.swift in Sources */ = {isa = PBXBuildFile; fileRef = A88B8C542D35F1EC00F53F9D /* OperationsLoggingControl.swift */; };
@@ -650,6 +656,10 @@
 		A80D60D12D3D705F00CEF65D /* ReleaseTrack.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ReleaseTrack.swift; sourceTree = "<group>"; };
 		A80D790C2D2F20AF00A40F40 /* PaginationIntent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PaginationIntent.swift; sourceTree = "<group>"; };
 		A80D790E2D2F217000A40F40 /* PaginationDataHolder.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PaginationDataHolder.swift; sourceTree = "<group>"; };
+		A81A8CB02D68B0320086C96F /* TreeMap.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TreeMap.swift; sourceTree = "<group>"; };
+		A81A8CB42D68B2180086C96F /* TreeMapTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TreeMapTests.swift; sourceTree = "<group>"; };
+		A81A8CBC2D68B43F0086C96F /* LinkedHashMap.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LinkedHashMap.swift; sourceTree = "<group>"; };
+		A81A8CBF2D68B4520086C96F /* LinkedHashMapTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LinkedHashMapTests.swift; sourceTree = "<group>"; };
 		A859ED5B2D1EE80D003DCC58 /* OpenSSL.xcframework */ = {isa = PBXFileReference; expectedSignature = "AppleDeveloperProgram:67RAULRX93:Marcin Krzyzanowski"; lastKnownFileType = wrapper.xcframework; name = OpenSSL.xcframework; path = SideStore/AltSign/Dependencies/OpenSSL/Frameworks/OpenSSL.xcframework; sourceTree = "<group>"; };
 		A85ACB8E2D1F31C400AA3DE7 /* AltBackup.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = AltBackup.xcconfig; sourceTree = "<group>"; };
 		A85ACB8F2D1F31C400AA3DE7 /* AltStore.debug.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = AltStore.debug.xcconfig; sourceTree = "<group>"; };
@@ -1227,6 +1237,23 @@
 			path = Intents;
 			sourceTree = "<group>";
 		};
+		A81A8CB22D68B2030086C96F /* UnitTests */ = {
+			isa = PBXGroup;
+			children = (
+				A81A8CB32D68B20F0086C96F /* datastructures */,
+			);
+			path = UnitTests;
+			sourceTree = "<group>";
+		};
+		A81A8CB32D68B20F0086C96F /* datastructures */ = {
+			isa = PBXGroup;
+			children = (
+				A81A8CBF2D68B4520086C96F /* LinkedHashMapTests.swift */,
+				A81A8CB42D68B2180086C96F /* TreeMapTests.swift */,
+			);
+			path = datastructures;
+			sourceTree = "<group>";
+		};
 		A85ACB942D1F31C400AA3DE7 /* xcconfigs */ = {
 			isa = PBXGroup;
 			children = (
@@ -1289,6 +1316,8 @@
 		A8AD35572D31BEB2003A28B4 /* datastructures */ = {
 			isa = PBXGroup;
 			children = (
+				A81A8CBC2D68B43F0086C96F /* LinkedHashMap.swift */,
+				A81A8CB02D68B0320086C96F /* TreeMap.swift */,
 				A868CFE32D319988002F1201 /* SingletonGenericMap.swift */,
 			);
 			path = datastructures;
@@ -1357,6 +1386,7 @@
 		A8E2DB352D6850A9009E5D31 /* Tests */ = {
 			isa = PBXGroup;
 			children = (
+				A81A8CB22D68B2030086C96F /* UnitTests */,
 				A8E2DB302D684E2A009E5D31 /* UITests */,
 				A8E2DB332D68507F009E5D31 /* SideStoreTests.xctestplan */,
 			);
@@ -2895,7 +2925,11 @@
 			buildActionMask = 2147483647;
 			files = (
 				A8E2DB312D684E2A009E5D31 /* UITests.swift in Sources */,
+				A81A8CB52D68B2180086C96F /* TreeMapTests.swift in Sources */,
+				A81A8CBB2D68B3230086C96F /* TreeMap.swift in Sources */,
 				A8E2DB322D684E2A009E5D31 /* UITestsLaunchTests.swift in Sources */,
+				A81A8CC02D68B4520086C96F /* LinkedHashMapTests.swift in Sources */,
+				A81A8CBE2D68B43F0086C96F /* LinkedHashMap.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -3100,6 +3134,7 @@
 			files = (
 				D55467C52A8D72C300F4CE90 /* ActiveAppsWidget.swift in Sources */,
 				D577AB7B2A967DF5007FE952 /* AppsTimelineProvider.swift in Sources */,
+				A81A8CB92D68B30B0086C96F /* SingletonGenericMap.swift in Sources */,
 				D577AB7F2A96878A007FE952 /* AppDetailWidget.swift in Sources */,
 				BF98917E250AAC4F002ACF50 /* Countdown.swift in Sources */,
 				D5151BE22A90363300C96F28 /* RefreshAllAppsWidgetIntent.swift in Sources */,
@@ -3108,7 +3143,6 @@
 				D5FD4EC92A9530C00097BEE8 /* AppSnapshot.swift in Sources */,
 				A8AD35592D31BF2C003A28B4 /* PageInfoManager.swift in Sources */,
 				D5151BE72A90395400C96F28 /* View+AltWidget.swift in Sources */,
-				A868CFE42D31999A002F1201 /* SingletonGenericMap.swift in Sources */,
 				A8A853AF2D3065A300995795 /* ActiveAppsTimelineProvider.swift in Sources */,
 				BF98917F250AAC4F002ACF50 /* LockScreenWidget.swift in Sources */,
 				A800F7042CE28E3800208744 /* View+AltWidget.swift in Sources */,
@@ -3142,6 +3176,7 @@
 				D5E1E7C128077DE90016FC96 /* UpdateKnownSourcesOperation.swift in Sources */,
 				BFE338DF22F0EADB002E24B9 /* FetchSourceOperation.swift in Sources */,
 				D54DED1428CBC44B008B27A0 /* ErrorLogTableViewCell.swift in Sources */,
+				A81A8CBD2D68B43F0086C96F /* LinkedHashMap.swift in Sources */,
 				D5390C3C2AC3A43900D17E62 /* AddSourceViewController.swift in Sources */,
 				D5CD805F29CA755E00E591B0 /* SourceDetailViewController.swift in Sources */,
 				D57968CB29CB99EF00539069 /* VibrantButton.swift in Sources */,
@@ -3224,6 +3259,7 @@
 				BF770E5122BB1CF6002A40FE /* InstallAppOperation.swift in Sources */,
 				BF9ABA4B22DD1380008935CF /* NavigationBar.swift in Sources */,
 				A8FD917B2D0472DD00322782 /* DeprecatedAPIs.swift in Sources */,
+				A81A8CBA2D68B3110086C96F /* TreeMap.swift in Sources */,
 				BF6C8FAC242935ED00125131 /* NSAttributedString+Markdown.m in Sources */,
 				A8C38C382D2084D000E83DBD /* ConsoleLogView.swift in Sources */,
 				BFF00D322501BDA100746320 /* BackgroundRefreshAppsOperation.swift in Sources */,
--- a/SideStore/Tests/SideStoreTests.xctestplan
+++ b/SideStore/Tests/SideStoreTests.xctestplan
@@ -18,6 +18,8 @@
  "testTargets" : [
    {
      "skippedTests" : [
+        "UITests",
+        "UITests\/testBulkAddRecommendedSources()",
        "UITests\/testLaunchPerformance()",
        "UITestsLaunchTests",
        "UITestsLaunchTests\/testLaunch()"
--- a/SideStore/Tests/UnitTests/datastructures/LinkedHashMapTests.swift
+++ b/SideStore/Tests/UnitTests/datastructures/LinkedHashMapTests.swift
@@ -0,0 +1,206 @@
+//
+//  LinkedHashMapTests.swift
+//  SideStore
+//
+//  Created by Magesh K on 21/02/25.
+//  Copyright © 2025 SideStore. All rights reserved.
+//
+
+import XCTest
+
+// A helper class that signals when it is deallocated.
+class LeakTester {
+    let id: Int
+    var onDeinit: (() -> Void)?
+    init(id: Int, onDeinit: (() -> Void)? = nil) {
+        self.id = id
+        self.onDeinit = onDeinit
+    }
+    deinit {
+        onDeinit?()
+    }
+}
+
+final class LinkedHashMapTests: XCTestCase {
+    
+    // Test that insertion preserves order and that iteration returns items in insertion order.
+    func testInsertionAndOrder() {
+        let map = LinkedHashMap<String, Int>()
+        map.put(key: "one", value: 1)
+        map.put(key: "two", value: 2)
+        map.put(key: "three", value: 3)
+        
+        XCTAssertEqual(map.count, 3)
+        XCTAssertEqual(map.keys, ["one", "two", "three"], "Insertion order should be preserved")
+        
+        var iteratedKeys = [String]()
+        for (key, _) in map {
+            iteratedKeys.append(key)
+        }
+        XCTAssertEqual(iteratedKeys, ["one", "two", "three"], "Iterator should follow insertion order")
+    }
+    
+    // Test that updating a key does not change its order.
+    func testUpdateDoesNotChangeOrder() {
+        let map = LinkedHashMap<String, Int>()
+        map.put(key: "a", value: 1)
+        map.put(key: "b", value: 2)
+        map.put(key: "c", value: 3)
+        // Update key "b"
+        map.put(key: "b", value: 20)
+        XCTAssertEqual(map.get(key: "b"), 20)
+        
+        XCTAssertEqual(map.keys, ["a", "b", "c"], "Order should not change on update")
+    }
+    
+    // Test removal functionality and behavior when removing a non-existent key.
+    func testRemoval() {
+        let map = LinkedHashMap<Int, String>()
+        map.put(key: 1, value: "one")
+        map.put(key: 2, value: "two")
+        map.put(key: 3, value: "three")
+        
+        let removed = map.remove(key: 2)
+        XCTAssertEqual(removed, "two")
+        XCTAssertEqual(map.count, 2)
+        XCTAssertEqual(map.keys, [1, 3])
+        
+        // Removing a key that doesn't exist should return nil.
+        let removedNil = map.remove(key: 4)
+        XCTAssertNil(removedNil)
+    }
+    
+    // Test clearing the map.
+    func testClear() {
+        let map = LinkedHashMap<String, Int>()
+        map.put(key: "x", value: 100)
+        map.put(key: "y", value: 200)
+        XCTAssertEqual(map.count, 2)
+        
+        map.clear()
+        XCTAssertEqual(map.count, 0)
+        XCTAssertTrue(map.isEmpty)
+        XCTAssertEqual(map.keys, [])
+        XCTAssertEqual(map.values, [])
+    }
+    
+    // Test subscript access for getting, updating, and removal.
+    func testSubscript() {
+        let map = LinkedHashMap<String, Int>()
+        map["alpha"] = 10
+        XCTAssertEqual(map["alpha"], 10)
+        
+        map["alpha"] = 20
+        XCTAssertEqual(map["alpha"], 20)
+        
+        // Setting a key to nil should remove the mapping.
+        map["alpha"] = nil
+        XCTAssertNil(map["alpha"])
+    }
+    
+    // Test containsKey and containsValue.
+    func testContains() {
+        let map = LinkedHashMap<String, Int>()
+        map.put(key: "key1", value: 1)
+        map.put(key: "key2", value: 2)
+        
+        XCTAssertTrue(map.containsKey("key1"))
+        XCTAssertFalse(map.containsKey("key3"))
+        
+        XCTAssertTrue(map.containsValue(1))
+        XCTAssertFalse(map.containsValue(99))
+    }
+    
+    // Test initialization from a dictionary.
+    func testInitializationFromDictionary() {
+        // Note: Swift dictionaries preserve insertion order for literals.
+        let dictionary: [String: Int] = ["a": 1, "b": 2, "c": 3]
+        let map = LinkedHashMap(dictionary)
+        XCTAssertEqual(map.count, 3)
+        // Order may differ since Dictionary order is not strictly defined – here we verify membership.
+        XCTAssertEqual(Set(map.keys), Set(["a", "b", "c"]))
+    }
+    
+    // Revised test that iterates over the map and compares key-value pairs element by element.
+    func testIteration() {
+        let map = LinkedHashMap<Int, String>()
+        let pairs = [(1, "one"), (2, "two"), (3, "three")]
+        for (key, value) in pairs {
+            map.put(key: key, value: value)
+        }
+        
+        var iteratedPairs = [(Int, String)]()
+        for (key, value) in map {
+            iteratedPairs.append((key, value))
+        }
+        
+        XCTAssertEqual(iteratedPairs.count, pairs.count, "Iterated count should match inserted count")
+        for (iter, expected) in zip(iteratedPairs, pairs) {
+            XCTAssertEqual(iter.0, expected.0, "Keys should match in order")
+            XCTAssertEqual(iter.1, expected.1, "Values should match in order")
+        }
+    }
+    
+    // Test that the values stored in the map are deallocated when the map is deallocated.
+    func testMemoryLeak() {
+        weak var weakMap: LinkedHashMap<Int, LeakTester>?
+        var deinitCalled = false
+        
+        do {
+            let map = LinkedHashMap<Int, LeakTester>()
+            let tester = LeakTester(id: 1) { deinitCalled = true }
+            map.put(key: 1, value: tester)
+            weakMap = map
+            XCTAssertNotNil(map.get(key: 1))
+        }
+        // At this point the map (and its stored objects) should be deallocated.
+        XCTAssertNil(weakMap, "LinkedHashMap should be deallocated when out of scope")
+        XCTAssertTrue(deinitCalled, "LeakTester should be deallocated, indicating no memory leak")
+    }
+    
+    // Test that removal from the map correctly frees stored objects.
+    func testMemoryLeakOnRemoval() {
+        var deinitCalledForTester1 = false
+        var deinitCalledForTester2 = false
+        
+        let map = LinkedHashMap<Int, LeakTester>()
+        autoreleasepool {
+            let tester1 = LeakTester(id: 1) { deinitCalledForTester1 = true }
+            let tester2 = LeakTester(id: 2) { deinitCalledForTester2 = true }
+            map.put(key: 1, value: tester1)
+            map.put(key: 2, value: tester2)
+            
+            XCTAssertNotNil(map.get(key: 1))
+            XCTAssertNotNil(map.get(key: 2))
+            
+            // Remove tester1; it should be deallocated if no retain cycle exists.
+            _ = map.remove(key: 1)
+        }
+        // tester1 should be deallocated immediately after removal.
+        XCTAssertTrue(deinitCalledForTester1, "Tester1 should be deallocated after removal")
+        // tester2 is still in the map.
+        XCTAssertNotNil(map.get(key: 2))
+        
+        // Clear the map and tester2 should be deallocated.
+        map.clear()
+        XCTAssertTrue(deinitCalledForTester2, "Tester2 should be deallocated after clearing the map")
+    }
+    
+    func testDefaultSubscriptExtension() {
+            // Create an instance of LinkedHashMap with String keys and Bool values.
+            let map = LinkedHashMap<String, Bool>()
+            
+            // Verify that accessing a non-existent key returns the default value (false).
+            XCTAssertEqual(map["testKey", default: false], false)
+            
+            // Use the default subscript setter to assign 'true' for the key.
+            map["testKey", default: false] = true
+            XCTAssertEqual(map["testKey", default: false], true)
+            
+            // Simulate in-place toggle: read the value, toggle it, then write it back.
+            var current = map["testKey", default: false]
+            current.toggle() // now false
+            map["testKey", default: false] = current
+            XCTAssertEqual(map["testKey", default: false], false)
+        }
+}
--- a/SideStore/Tests/UnitTests/datastructures/TreeMapTests.swift
+++ b/SideStore/Tests/UnitTests/datastructures/TreeMapTests.swift
@@ -0,0 +1,154 @@
+//
+//  TreeMapTests.swift
+//  AltStore
+//
+//  Created by Magesh K on 21/02/25.
+//  Copyright © 2025 SideStore. All rights reserved.
+//
+
+
+import XCTest
+
+class TreeMapTests: XCTestCase {
+    
+    func testInsertionAndRetrieval() {
+        let map = TreeMap<Int, String>()
+        XCTAssertNil(map[10])
+        map[10] = "ten"
+        XCTAssertEqual(map[10], "ten")
+        
+        map[5] = "five"
+        map[15] = "fifteen"
+        XCTAssertEqual(map.count, 3)
+        XCTAssertEqual(map[5], "five")
+        XCTAssertEqual(map[15], "fifteen")
+    }
+    
+    func testUpdateValue() {
+        let map = TreeMap<Int, String>()
+        map[10] = "ten"
+        let oldValue = map.insert(key: 10, value: "TEN")
+        XCTAssertEqual(oldValue, "ten")
+        XCTAssertEqual(map[10], "TEN")
+        XCTAssertEqual(map.count, 1)
+    }
+    
+    func testDeletion() {
+        let map = TreeMap<Int, String>()
+        // Setup: Inserting three nodes.
+        map[20] = "twenty"
+        map[10] = "ten"
+        map[30] = "thirty"
+        
+        // Remove a leaf node.
+        let removedLeaf = map.remove(key: 10)
+        XCTAssertEqual(removedLeaf, "ten")
+        XCTAssertNil(map[10])
+        XCTAssertEqual(map.count, 2)
+        
+        // Setup additional nodes to create a one-child scenario.
+        map[25] = "twenty-five"
+        map[27] = "twenty-seven" // Right child for 25.
+        // Remove a node with one child.
+        let removedOneChild = map.remove(key: 25)
+        XCTAssertEqual(removedOneChild, "twenty-five")
+        XCTAssertNil(map[25])
+        XCTAssertEqual(map.count, 3)
+        
+        // Setup for a node with two children.
+        map[40] = "forty"
+        map[35] = "thirty-five"
+        map[45] = "forty-five"
+        // Remove a node with two children.
+        let removedTwoChildren = map.remove(key: 40)
+        XCTAssertEqual(removedTwoChildren, "forty")
+        XCTAssertNil(map[40])
+        XCTAssertEqual(map.count, 5)
+    }
+    
+    func testDeletionOfRoot() {
+        let map = TreeMap<Int, String>()
+        map[50] = "fifty"
+        map[30] = "thirty"
+        map[70] = "seventy"
+        
+        // Delete the root node.
+        let removedRoot = map.remove(key: 50)
+        XCTAssertEqual(removedRoot, "fifty")
+        XCTAssertNil(map[50])
+        // After deletion, remaining keys should be in sorted order.
+        XCTAssertEqual(map.keys, [30, 70])
+    }
+    
+    func testSortedIteration() {
+        let map = TreeMap<Int, String>()
+        let keys = [20, 10, 30, 5, 15, 25, 35]
+        for key in keys {
+            map[key] = "\(key)"
+        }
+        let sortedKeys = map.keys
+        XCTAssertEqual(sortedKeys, keys.sorted())
+        
+        // Verify in-order traversal.
+        var previous: Int? = nil
+        for (key, value) in map {
+            if let prev = previous {
+                XCTAssertLessThanOrEqual(prev, key)
+            }
+            previous = key
+            XCTAssertEqual(value, "\(key)")
+        }
+    }
+    
+    func testRemoveAll() {
+        let map = TreeMap<Int, String>()
+        for i in 0..<100 {
+            map[i] = "\(i)"
+        }
+        XCTAssertEqual(map.count, 100)
+        map.removeAll()
+        XCTAssertEqual(map.count, 0)
+        XCTAssertTrue(map.isEmpty)
+    }
+    
+    func testBalancing() {
+        let map = TreeMap<Int, Int>()
+        // Insert elements in ascending order to challenge the balancing.
+        for i in 1...1000 {
+            map[i] = i
+        }
+        // Verify in-order traversal produces sorted order.
+        var expected = 1
+        for (key, value) in map {
+            XCTAssertEqual(key, expected)
+            XCTAssertEqual(value, expected)
+            expected += 1
+        }
+        XCTAssertEqual(expected - 1, 1000)
+        
+        // Remove odd keys to force rebalancing.
+        for i in stride(from: 1, through: 1000, by: 2) {
+            _ = map.remove(key: i)
+        }
+        let expectedEvenKeys = (1...1000).filter { $0 % 2 == 0 }
+        XCTAssertEqual(map.keys, expectedEvenKeys)
+    }
+    
+    func testNonExistentDeletion() {
+        let map = TreeMap<Int, String>()
+        map[10] = "ten"
+        let removed = map.remove(key: 20)
+        XCTAssertNil(removed)
+        XCTAssertEqual(map.count, 1)
+    }
+    
+    func testDuplicateInsertion() {
+        let map = TreeMap<String, String>()
+        map["a"] = "first"
+        XCTAssertEqual(map["a"], "first")
+        let oldValue = map.insert(key: "a", value: "second")
+        XCTAssertEqual(oldValue, "first")
+        XCTAssertEqual(map["a"], "second")
+        XCTAssertEqual(map.count, 1)
+    }
+}