cabana: switching endianness of a signal located in a single byte doesn't change bit coverage

src/__tests__/components/AddSignals.test.js

@@ -288,3 +288,20 @@ test('a big endian signal spanning one byte should switch to little endian prese
     expect(signal.isLittleEndian).toBe(true);
     expect(signal.startBit).toBe(0);
 });
+
+test('dragging the msb of a 2-bit little endian signal to a lower byte should not change the signal', () => {
+    const component = createAddSignals();
+    component.instance().createSignal({startBit: 14, size: 2, isLittleEndian: true});
+
+    const msb = component.find('.bit').at(8);
+    msb.simulate('mousedown');
+    const bitOutOfBounds = component.find('.bit').at(0);
+    bitOutOfBounds.simulate('mouseenter');
+    bitOutOfBounds.simulate('mouseup');
+
+    const signal = Object.values(component.state('signals'))[0];
+    expect(signal).toBeDefined();
+    expect(signal.size).toBe(2);
+    expect(signal.isLittleEndian).toBe(true);
+    expect(signal.startBit).toBe(14);
+});

src/__tests__/components/SignalLegendEntry.test.js

@@ -14,31 +14,34 @@ afterEach(() => {
 });
 
 function createSignalLegendEntry(props) {
-    let signal = props.signal, onSignalChange = props.onSignalChange;
+    let signal = props.signal,
+        onSignalChange = props.onSignalChange,
+        onTentativeSignalChange = props.onTentativeSignalChange;
     if(signal === undefined) {
         signal = new Signal({name: 'NEW_SIGNAL'});
     }
     if(onSignalChange === undefined) {
         onSignalChange = () => {};
     }
+    if(onTentativeSignalChange === undefined) {
+        onTentativeSignalChange = () => {};
+    }
 
     return shallow(<SignalLegendEntry
                      highlightedStyle={null}
                      signal={signal}
                      onSignalChange={onSignalChange}
+                     onTentativeSignalChange={onTentativeSignalChange}
                     />);
 }
 
 test('a little endian signal spanning one byte should adjust its startBit switching to big endian, preserving its bit coverage', () => {
-    const mockOnSignalChange = jest.fn();
-
     const signal = new Signal({name: 'signal',
                                startBit: 0,
                                size: 8,
                                isLittleEndian: true});
-    const props = {onSignalChange: mockOnSignalChange,
-                   signal};
-    const component = createSignalLegendEntry(props);
+
+    const component = createSignalLegendEntry({signal});
     const endiannessFieldSpec = SignalLegendEntry.fieldSpecForName('isLittleEndian');
     component.instance().updateField(endiannessFieldSpec, false);
 
@@ -49,15 +52,11 @@ test('a little endian signal spanning one byte should adjust its startBit switch
 });
 
 test('a big endian signal spanning two bytes should should adjust its startBit switching to little endian, preserving its bit coverage', () => {
-    const mockOnSignalChange = jest.fn();
-
     const signal = new Signal({name: 'signal',
                                startBit: 7,
                                size: 8,
                                isLittleEndian: false});
-    const props = {onSignalChange: mockOnSignalChange,
-                   signal};
-    const component = createSignalLegendEntry(props);
+    const component = createSignalLegendEntry({signal});
     const endiannessFieldSpec = SignalLegendEntry.fieldSpecForName('isLittleEndian');
     component.instance().updateField(endiannessFieldSpec, true);
 
@@ -68,15 +67,12 @@ test('a big endian signal spanning two bytes should should adjust its startBit s
 });
 
 test("a big endian signal spanning one and a half bytes should adjust its startBit switching to little endian, preserving the first byte's coverage", () => {
-    const mockOnSignalChange = jest.fn();
-
     const signal = new Signal({name: 'signal',
                                startBit: 7,
                                size: 12,
                                isLittleEndian: false});
-    const props = {onSignalChange: mockOnSignalChange,
-                   signal};
-    const component = createSignalLegendEntry(props);
+
+    const component = createSignalLegendEntry({signal});
     const endiannessFieldSpec = SignalLegendEntry.fieldSpecForName('isLittleEndian');
     component.instance().updateField(endiannessFieldSpec, true);
 
@@ -85,3 +81,33 @@ test("a big endian signal spanning one and a half bytes should adjust its startB
     expect(signalEdited.startBit).toBe(0);
     expect(signalEdited.size).toBe(12);
 });
+
+test('a little endian signal spanning 3 bits on one byte should adjust its startBit switching to big endian, preserving its bit coverage', () => {
+    const signal = new Signal({name: 'signal',
+                               startBit: 13,
+                               size: 3,
+                               isLittleEndian: true});
+    const component = createSignalLegendEntry({signal});
+    const endiannessFieldSpec = SignalLegendEntry.fieldSpecForName('isLittleEndian');
+    component.instance().updateField(endiannessFieldSpec, false);
+
+    const signalEdited = component.state('signalEdited');
+    expect(signalEdited.isLittleEndian).toBe(false);
+    expect(signalEdited.startBit).toBe(15);
+    expect(signalEdited.size).toBe(3);
+});
+
+test('a big endian signal spanning 3 bytes on one byte should adjust its startBit switching to little endian, preserving its bit coverage', () => {
+    const signal = new Signal({name: 'signal',
+                               startBit: 15,
+                               size: 3,
+                               isLittleEndian: false});
+    const component = createSignalLegendEntry({signal});
+    const endiannessFieldSpec = SignalLegendEntry.fieldSpecForName('isLittleEndian');
+    component.instance().updateField(endiannessFieldSpec, true);
+
+    const signalEdited = component.state('signalEdited');
+    expect(signalEdited.isLittleEndian).toBe(true);
+    expect(signalEdited.startBit).toBe(13);
+    expect(signalEdited.size).toBe(3);
+});

src/components/AddSignals.js

@@ -194,6 +194,10 @@ export default class AddSignals extends Component {
                         }
                     }
                 } else if(dragSignal.isLittleEndian && dragStartBit === dragSignal.msbBitIndex()) {
+                    if(bitIdx < dragSignal.startBit) {
+                        // should not be able to drag the MSB past the LSB
+                        return;
+                    }
                     const diff = bitIdx - dragStartBit;
                     if(dragSignal.bitDescription(bitIdx) === null) {
                         dragSignal.size += Math.abs(diff);

src/components/SignalLegendEntry.js

@@ -60,12 +60,27 @@ export default class SignalLegendEntry extends Component {
             transform: (isLittleEndian, signal) => {
                 if(signal.isLittleEndian !== isLittleEndian) {
                     const {startBit} = signal;
+
                     if(isLittleEndian) {
                         // big endian -> little endian
-                        signal.startBit = DbcUtils.matrixBitNumber(startBit);
+                        const startByte = Math.floor(signal.startBit / 8),
+                              endByte = Math.floor((signal.startBit - signal.size + 1) / 8);
+
+                        if(startByte === endByte) {
+                            signal.startBit = signal.startBit - signal.size + 1;
+                        } else {
+                            signal.startBit = DbcUtils.matrixBitNumber(startBit);
+                        }
                     } else {
                         // little endian -> big endian
-                        signal.startBit = DbcUtils.bigEndianBitIndex(startBit);
+                        const startByte = Math.floor(signal.startBit / 8),
+                              endByte = Math.floor((signal.startBit + signal.size - 1) / 8);
+
+                        if(startByte === endByte) {
+                            signal.startBit = signal.startBit + signal.size - 1;
+                        } else {
+                            signal.startBit = DbcUtils.bigEndianBitIndex(startBit);
+                        }
                     }
                     signal.isLittleEndian = isLittleEndian;
                 }
@@ -125,6 +140,7 @@ export default class SignalLegendEntry extends Component {
         };
 
         this.toggleEditing = this.toggleEditing.bind(this);
+        this.updateField = this.updateField.bind(this);
     }
 
     componentWillReceiveProps(nextProps) {