Setting to highlight cells with an incorrect digit

src/components/modal/modal-settings.js

@@ -75,6 +75,12 @@ export default function ModalSettings({modalHandler, modalState}) {
                     allSettings={allSettings}
                     setSetting={setSetting}
                 />
+                <CheckBoxSetting
+                    name={SETTINGS.highlightErrors}
+                    text="Highlight errors"
+                    allSettings={allSettings}
+                    setSetting={setSetting}
+                />
                 <CheckBoxSetting
                     name={SETTINGS.autocleanPencilmarks}
                     text="Auto-clean pencil marks"

src/lib/sudoku-model.js

@@ -32,6 +32,7 @@ export const SETTINGS = {
     outlineSelection: "outline-selection",
     highlightMatches: "highlight-matches",
     highlightConflicts: "highlight-conflicts",
+    highlightErrors: "highlight-errors",
     autocleanPencilmarks: "autoclean-pencilmarks",
     flipNumericKeys: "flip-numeric-keys",
     playVictoryAnimation: "play-victory-animation",
@@ -149,6 +150,7 @@ export const modelHelpers = {
         [SETTINGS.outlineSelection]: false,
         [SETTINGS.highlightMatches]: true,
         [SETTINGS.highlightConflicts]: true,
+        [SETTINGS.highlightErrors]: false,
         [SETTINGS.autocleanPencilmarks]: true,
         [SETTINGS.flipNumericKeys]: false,
         [SETTINGS.playVictoryAnimation]: true,
@@ -1415,7 +1417,8 @@ export const modelHelpers = {
     },
 
     applyErrorHighlights: (grid, errorAtIndex = {}) => {
-        if (!modelHelpers.getSetting(grid, SETTINGS.highlightConflicts)) {
+        if (!modelHelpers.getSetting(grid, SETTINGS.highlightConflicts)
+            && !modelHelpers.getSetting(grid, SETTINGS.highlightErrors)) {
             return grid;
         }
         const cells = grid.get('cells').map((c) => {
@@ -1607,7 +1610,10 @@ export const modelHelpers = {
 
     checkCompletedDigits: (grid) => {
         const digits = grid.get('cells').map(c => c.get('digit')).join('');
-        const result = modelHelpers.checkDigits(digits);
+        const finalDigits = grid.get('finalDigits');
+        const result = modelHelpers.getSetting(grid, SETTINGS.highlightErrors)
+            ? modelHelpers.checkDigits(digits, finalDigits)
+            : modelHelpers.checkDigits(digits);
         grid = grid.set('completedDigits', result.completedDigits);
         if (result.isSolved && !grid.get('endTime')) {
             return modelHelpers.setGridSolved(grid);

src/lib/sudoku-model.test.js

@@ -557,6 +557,39 @@ test('no highlight conflicts', () => {
     });
 });
 
+test('set highlight errors', () => {
+    let grid = newSudokuModel({initialDigits: initialDigitsComplete});
+    const settings = grid.get('settings');
+    grid = grid.set('settings', { ...settings, [SETTINGS.highlightErrors]: true});
+
+    expect(grid.get('currentSnapshot')).toBe('');
+    grid = modelHelpers.applySelectionOp(grid, 'setSelection', 8);
+    grid = modelHelpers.updateSelectedCells(grid, 'setDigit', '9');
+
+    expect(grid.get('currentSnapshot')).toBe('19D9');
+    expect(grid.get('matchDigit')).toBe('9');
+
+    let c8 = grid.get('cells').get(8);
+    expect(c8.get('digit')).toBe('9');
+    expect(c8.get('snapshot')).toBe('D9');
+    expect(c8.get('errorMessage')).toBe('Incorrect digit');
+    expect(c8.get('isGiven')).toBe(false);
+    expect(c8.get('isSelected')).toBe(true);
+
+    // clear the cell and expect it should have no error
+    grid = modelHelpers.applySelectionOp(grid, 'setSelection', 8);
+    grid = modelHelpers.updateSelectedCells(grid, 'clearCell');
+
+    expect(grid.get('currentSnapshot')).toBe('');
+
+    c8 = grid.get('cells').get(8);
+    expect(c8.get('digit')).toBe('0');
+    expect(c8.get('snapshot')).toBe('');
+    expect(c8.get('errorMessage')).toBe(undefined);
+    expect(c8.get('isGiven')).toBe(false);
+    expect(c8.get('isSelected')).toBe(true);
+});
+
 test('set cell color', () => {
     let grid = newSudokuModel({initialDigits: initialDigitsPartial, skipCheck: true});