diff --git a/McBopomofo.xcodeproj/project.pbxproj b/McBopomofo.xcodeproj/project.pbxproj
index 0e608666..c4ae5ad4 100644
--- a/McBopomofo.xcodeproj/project.pbxproj
+++ b/McBopomofo.xcodeproj/project.pbxproj
@@ -60,7 +60,7 @@
 		D485D3B92796A8A000657FF3 /* PreferencesTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D485D3B82796A8A000657FF3 /* PreferencesTests.swift */; };
 		D485D3C02796CE3200657FF3 /* VersionUpdateTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D485D3BF2796CE3200657FF3 /* VersionUpdateTests.swift */; };
 		D4E569DC27A34D0E00AC2CEF /* KeyHandler.mm in Sources */ = {isa = PBXBuildFile; fileRef = D4E569DB27A34CC100AC2CEF /* KeyHandler.mm */; };
-		D4E569DF27A40F1400AC2CEF /* KeyHandlerTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = D4E569DE27A40F1400AC2CEF /* KeyHandlerTests.mm */; };
+		D4E569DF27A40F1400AC2CEF /* KeyHandlerBopomofoTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = D4E569DE27A40F1400AC2CEF /* KeyHandlerBopomofoTests.mm */; };
 		D4E569E027A4123200AC2CEF /* KeyHandlerInput.swift in Sources */ = {isa = PBXBuildFile; fileRef = D456576D279E4F7B00DF6BC9 /* KeyHandlerInput.swift */; };
 		D4E569E127A4128300AC2CEF /* InputState.swift in Sources */ = {isa = PBXBuildFile; fileRef = D461B791279DAC010070E734 /* InputState.swift */; };
 		D4E569E227A412E700AC2CEF /* Preferences.swift in Sources */ = {isa = PBXBuildFile; fileRef = D44FB74427915555003C80A6 /* Preferences.swift */; };
@@ -224,7 +224,7 @@
 		D4E569DA27A34CC100AC2CEF /* KeyHandler.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = KeyHandler.h; sourceTree = "<group>"; };
 		D4E569DB27A34CC100AC2CEF /* KeyHandler.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = KeyHandler.mm; sourceTree = "<group>"; };
 		D4E569DD27A40F1300AC2CEF /* McBopomofoTests-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "McBopomofoTests-Bridging-Header.h"; sourceTree = "<group>"; };
-		D4E569DE27A40F1400AC2CEF /* KeyHandlerTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = KeyHandlerTests.mm; sourceTree = "<group>"; };
+		D4E569DE27A40F1400AC2CEF /* KeyHandlerBopomofoTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = KeyHandlerBopomofoTests.mm; sourceTree = "<group>"; };
 		D4F0BBDE279AF1AF0071253C /* ArchiveUtil.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ArchiveUtil.swift; sourceTree = "<group>"; };
 		D4F0BBE0279AF8B30071253C /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		D4F0BBE2279B08900071253C /* BundleTranslocate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = BundleTranslocate.h; sourceTree = "<group>"; };
@@ -502,7 +502,7 @@
 			children = (
 				D485D3B82796A8A000657FF3 /* PreferencesTests.swift */,
 				D485D3BF2796CE3200657FF3 /* VersionUpdateTests.swift */,
-				D4E569DE27A40F1400AC2CEF /* KeyHandlerTests.mm */,
+				D4E569DE27A40F1400AC2CEF /* KeyHandlerBopomofoTests.mm */,
 				D4E569DD27A40F1300AC2CEF /* McBopomofoTests-Bridging-Header.h */,
 			);
 			path = McBopomofoTests;
@@ -750,7 +750,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				D4E569DF27A40F1400AC2CEF /* KeyHandlerTests.mm in Sources */,
+				D4E569DF27A40F1400AC2CEF /* KeyHandlerBopomofoTests.mm in Sources */,
 				D485D3B92796A8A000657FF3 /* PreferencesTests.swift in Sources */,
 				D4E569E227A412E700AC2CEF /* Preferences.swift in Sources */,
 				D4E569E127A4128300AC2CEF /* InputState.swift in Sources */,
diff --git a/McBopomofoTests/KeyHandlerBopomofoTests.mm b/McBopomofoTests/KeyHandlerBopomofoTests.mm
new file mode 100644
index 00000000..7c2589cf
--- /dev/null
+++ b/McBopomofoTests/KeyHandlerBopomofoTests.mm
@@ -0,0 +1,655 @@
+#import <XCTest/XCTest.h>
+#import "KeyHandler.h"
+#import "LanguageModelManager.h"
+#import "McBopomofoTests-Swift.h"
+
+@interface KeyHandlerBopomofoTests : XCTestCase
+
+@end
+
+@implementation KeyHandlerBopomofoTests
+
+- (void)setUp
+{
+    [LanguageModelManager loadDataModels];
+}
+
+- (void)tearDown
+{
+}
+
+- (void)testPunctuationComma
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"<" keyCode:0 charCode:'<' flags:NSEventModifierFlagShift isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"，"], @"It should be ， but %@", composingBuffer);
+}
+
+- (void)testPunctuationPeriod
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@">" keyCode:0 charCode:'>' flags:NSEventModifierFlagShift isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"。"], @"It should be 。 but %@", composingBuffer);
+}
+
+- (void)testInputtingNihao
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+}
+
+- (void)testCommittingNihao
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    __block NSInteger count = 0;
+
+    __block InputState *empty;
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:0 charCode:13 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        if (!count) {
+            state = inState;
+        }
+        empty = inState;
+        count++;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateCommitting")], @"It should be a committing state %@.", NSStringFromClass([state class]));
+    NSString *poppedText = [(InputStateCommitting *)state poppedText];
+    XCTAssertTrue([poppedText isEqualToString:@"你好"], @"It should be 你好 but %@", poppedText);
+
+    XCTAssertTrue([empty isKindOfClass:NSClassFromString(@"McBopomofo.InputStateEmpty")], @"It should be an empty state %@.", NSStringFromClass([state class]));
+}
+
+- (void)testDelete
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 2);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:123 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 1);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:117 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你"], @"It should be 你 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 1);
+
+    __block BOOL errorCalled = NO;
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:117 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+        errorCalled = YES;
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你"], @"It should be 你 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 1);
+    XCTAssertTrue(errorCalled);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:123 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你"], @"It should be 你 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 0);
+
+    errorCalled = NO;
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:117 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+        errorCalled = YES;
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateEmptyIgnoringPreviousState")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    XCTAssertFalse(errorCalled);
+}
+
+- (void)testBackspace
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:0 charCode:8 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你"], @"It should be 你 but %@", composingBuffer);
+
+    __block InputStateEmpty *empty;
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:0 charCode:8 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        empty = (InputStateEmpty *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([empty isKindOfClass:NSClassFromString(@"McBopomofo.InputStateEmptyIgnoringPreviousState")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+}
+
+- (void)testCursor
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 2);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:123 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 1);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:123 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 0);
+
+    __block BOOL errorCalled = NO;
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:123 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+        errorCalled = YES;
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 0);
+    XCTAssertTrue(errorCalled);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:124 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 1);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:124 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 2);
+
+    errorCalled = NO;
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:124 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = (InputStateInputting *)inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+        errorCalled = YES;
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 2);
+    XCTAssertTrue(errorCalled);
+}
+
+- (void)testCandidateWithDown
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:125 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateChoosingCandidate")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
+    NSArray *candidates = [(InputStateChoosingCandidate *)state candidates];
+    XCTAssertTrue([candidates containsObject:@"你"]);
+
+}
+
+- (void)testHomeAndEnd
+{
+    KeyHandler *handler = [[KeyHandler alloc] init];
+    handler.inputMode = kBopomofoModeIdentifier;
+
+    KeyHandlerInput *input;
+    __block InputState *state;
+    state = [[InputStateEmpty alloc] init];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 2);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:115 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 0);
+
+    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:119 charCode:0 flags:0 isVerticalMode:0];
+    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
+        state = inState;
+    } candidateSelectionCallback:^{
+    } errorCallback:^{
+    }];
+
+    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
+    composingBuffer = [(InputStateInputting *)state composingBuffer];
+    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
+    XCTAssertEqual([(InputStateInputting *)state cursorIndex], 2);
+
+}
+
+@end
+
diff --git a/McBopomofoTests/KeyHandlerTests.mm b/McBopomofoTests/KeyHandlerTests.mm
deleted file mode 100644
index 696e79b1..00000000
--- a/McBopomofoTests/KeyHandlerTests.mm
+++ /dev/null
@@ -1,230 +0,0 @@
-#import <XCTest/XCTest.h>
-#import "KeyHandler.h"
-#import "LanguageModelManager.h"
-#import "McBopomofoTests-Swift.h"
-
-@interface KeyHandlerTests : XCTestCase
-
-@end
-
-@implementation KeyHandlerTests
-
-- (void)setUp
-{
-    [LanguageModelManager loadDataModels];
-}
-
-- (void)tearDown
-{
-}
-
-- (void)testInputtingNihaoUsingMcBopomofo
-{
-    KeyHandler *handler = [[KeyHandler alloc] init];
-    handler.inputMode = kBopomofoModeIdentifier;
-
-    KeyHandlerInput *input;
-    __block InputState *state;
-    state = [[InputStateEmpty alloc] init];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
-    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
-    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
-}
-
-- (void)testComittingNihaoUsingMcBopomofo
-{
-    KeyHandler *handler = [[KeyHandler alloc] init];
-    handler.inputMode = kBopomofoModeIdentifier;
-
-    KeyHandlerInput *input;
-    __block InputState *state;
-    state = [[InputStateEmpty alloc] init];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    __block NSInteger count = 0;
-
-    __block InputState *empty;
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:0 charCode:13 flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        if (!count) {
-            state = inState;
-        }
-        empty = inState;
-        count++;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateCommitting")], @"It should be a committing state %@.", NSStringFromClass([state class]));
-    NSString *poppedText = [(InputStateCommitting *)state poppedText];
-    XCTAssertTrue([poppedText isEqualToString:@"你好"], @"It should be 你好 but %@", poppedText);
-
-    XCTAssertTrue([empty isKindOfClass:NSClassFromString(@"McBopomofo.InputStateEmpty")], @"It should be an empty state %@.", NSStringFromClass([state class]));
-}
-
-
-- (void)testBackspaceUsingMcBopomofo
-{
-    KeyHandler *handler = [[KeyHandler alloc] init];
-    handler.inputMode = kBopomofoModeIdentifier;
-
-    KeyHandlerInput *input;
-    __block InputState *state;
-    state = [[InputStateEmpty alloc] init];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"s" keyCode:0 charCode:'s' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"u" keyCode:0 charCode:'u' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"c" keyCode:0 charCode:'c' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"l" keyCode:0 charCode:'l' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@"3" keyCode:0 charCode:'3' flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be an inputting state %@.", NSStringFromClass([state class]));
-    NSString *composingBuffer = [(InputStateInputting *)state composingBuffer];
-    XCTAssertTrue([composingBuffer isEqualToString:@"你好"], @"It should be 你好 but %@", composingBuffer);
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:0 charCode:8 flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        state = (InputStateInputting *)inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    XCTAssertTrue([state isKindOfClass:NSClassFromString(@"McBopomofo.InputStateInputting")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
-    composingBuffer = [(InputStateInputting *)state composingBuffer];
-    XCTAssertTrue([composingBuffer isEqualToString:@"你"], @"It should be 你 but %@", composingBuffer);
-
-    __block InputStateEmpty *empty;
-
-    input = [[KeyHandlerInput alloc] initWithInputText:@" " keyCode:0 charCode:8 flags:0 isVerticalMode:0];
-    [handler handleInput:input state:state stateCallback:^(InputState * inState) {
-        empty = (InputStateEmpty *)inState;
-    } candidateSelectionCallback:^{
-    } errorCallback:^{
-    }];
-
-    XCTAssertTrue([empty isKindOfClass:NSClassFromString(@"McBopomofo.InputStateEmptyIgnoringPreviousState")], @"It should be a inputting state %@.", NSStringFromClass([state class]));
-}
-
-@end
-