fix(ui): [input-amount] make sure that previous locale is not used for parsing on user-edit with <= 2 decimals

.changeset/odd-feet-teach.md

@@ -0,0 +1,5 @@
+---
+'@lion/ui': patch
+---
+
+[input-amount] make sure that previous locale is not used for parsing on user-edit with <= 2 decimals

packages/ui/components/input-amount/test/lion-input-amount.test.js

@@ -131,7 +131,7 @@ describe('<lion-input-amount>', () => {
     expect(_inputNode.value).to.equal('100.12');
   });
 
-  it('adjusts formats with locale when formatOptions.mode is "user-edited"', async () => {
+  it('formats with locale when formatOptions.mode is "user-edited" and value has three decimal places', async () => {
     const el = /** @type {LionInputAmount} */ (
       await fixture(
         html`<lion-input-amount
@@ -154,6 +154,14 @@ describe('<lion-input-amount>', () => {
     expect(el.modelValue).to.equal(123456);
     expect(el.formattedValue).to.equal('123.456,00');
 
+    // When editing an already existing value, we interpet the separators as they are.
+    // However, only when the decimal places are 3 or more.
+    mimicUserInput(el, '123.456.00');
+    expect(parserSpy.lastCall.args[1]?.mode).to.equal('user-edited');
+    expect(formatterSpy.lastCall.args[1]?.mode).to.equal('user-edited');
+    expect(el.modelValue).to.equal(123456);
+    expect(el.formattedValue).to.equal('123.456,00');
+
     // Formatting should only affect values that should be formatted / parsed as a consequence of user input.
     // When a user finished editing, the default should be restored.
     // (think of a programmatically set modelValue, that should behave idempotent, regardless of when it is set)
@@ -162,6 +170,45 @@ describe('<lion-input-amount>', () => {
     expect(formatterSpy.lastCall.args[1]?.mode).to.equal('auto');
   });
 
+  it('formats with heuristic when formatOptions.mode is "user-edited" and value has two decimal places', async () => {
+    const el = /** @type {LionInputAmount} */ (
+      await fixture(
+        html`<lion-input-amount
+          .modelValue=${64}
+          currency="EUR"
+          .formatOptions="${{ locale: 'en-GB' }}"
+        ></lion-input-amount>`,
+      )
+    );
+    const parserSpy = sinon.spy(el, 'parser');
+    const formatterSpy = sinon.spy(el, 'formatter');
+
+    expect(el.formattedValue).to.equal('64.00');
+    // @ts-expect-error [allow-protected] in test
+    expect(el._inputNode.value).to.equal('64.00');
+
+    // When editing an already existing value, we interpret the separators based on decimal places when there's 1 or
+    // less separator in total (otherwise we would accidentally multiply or divide by 1000)
+    mimicUserInput(el, '64,00');
+    expect(parserSpy.lastCall.args[1]?.mode).to.equal('user-edited');
+    expect(formatterSpy.lastCall.args[1]?.mode).to.equal('user-edited');
+    expect(el.modelValue).to.equal(64);
+    expect(el.formattedValue).to.equal('64.00');
+
+    mimicUserInput(el, '64,0');
+    expect(parserSpy.lastCall.args[1]?.mode).to.equal('user-edited');
+    expect(formatterSpy.lastCall.args[1]?.mode).to.equal('user-edited');
+    expect(el.modelValue).to.equal(64);
+    expect(el.formattedValue).to.equal('64.00');
+
+    // Formatting should only affect values that should be formatted / parsed as a consequence of user input.
+    // When a user finished editing, the default should be restored.
+    // (think of a programmatically set modelValue, that should behave idempotent, regardless of when it is set)
+    el.modelValue = 1234;
+    expect(el.formattedValue).to.equal('1,234.00');
+    expect(formatterSpy.lastCall.args[1]?.mode).to.equal('auto');
+  });
+
   it('sets inputmode attribute to decimal', async () => {
     const el = /** @type {LionInputAmount} */ (
       await fixture(`<lion-input-amount></lion-input-amount>`)

packages/ui/components/input-amount/test/parsers.test.js

@@ -69,6 +69,6 @@ describe('parseAmount()', async () => {
     expect(parseAmount('123.456,78', { mode: 'auto' })).to.equal(123456.78);
     expect(
       parseAmount('123.456,78', { mode: 'user-edited', viewValueStates: ['formatted'] }),
-    ).to.equal(123.45678);
+    ).to.equal(123456.78);
   });
 });

packages/ui/components/localize/src/number/parseNumber.js

@@ -20,25 +20,34 @@ import { getDecimalSeparator } from './getDecimalSeparator.js';
  * @return {string} unparseable|withLocale|heuristic
  */
 function getParseMode(value, { mode = 'auto', viewValueStates } = {}) {
-  const separators = value.match(/[., ]/g);
-
-  // When a user edits an existing value, we already formatted it with a certain locale.
-  // For best UX, we stick with this locale
-  const shouldAlignWithExistingSeparators =
+  const separatorsRe = /[., ]/g;
+  const separators = value.match(separatorsRe) || [];
+  // @ts-expect-error [wait-for-platform-types]
+  const decimalPlaces = (value.split(separatorsRe) || []).at(-1).length;
+  const isCurViewFormattedAndUserIsEditing =
     viewValueStates?.includes('formatted') && mode === 'user-edited';
 
-  if (!separators || shouldAlignWithExistingSeparators) {
+  // When a user edits an existing value, we already formatted it with a certain locale.
+  // For best UX, we stick with this locale. However, we only do this when the user has
+  // entered at least 3 decimal places.
+  const shouldUseCurLocale = isCurViewFormattedAndUserIsEditing && decimalPlaces > 2;
+
+  const shouldUseLocale =
+    shouldUseCurLocale ||
+    !separators.length ||
+    (mode === 'auto' && separators.length === 1 && decimalPlaces >= 3);
+  if (shouldUseLocale) {
     return 'withLocale';
   }
-  if (mode === 'auto' && separators.length === 1) {
-    const decimalLength = value.split(`${separators}`)[1].length;
-    if (decimalLength >= 3) {
-      return 'withLocale';
-    }
-  }
-  if (separators.length === 1 || separators[0] !== separators[separators.length - 1]) {
+
+  const shouldUseHeuristic =
+    (isCurViewFormattedAndUserIsEditing && decimalPlaces <= 2) ||
+    separators.length === 1 ||
+    separators[0] !== separators[separators.length - 1];
+  if (shouldUseHeuristic) {
     return 'heuristic';
   }
+
   return 'unparseable';
 }
 

packages/ui/components/localize/test/number/parseNumber.test.js

@@ -82,7 +82,7 @@ describe('parseNumber()', () => {
     expect(parseNumber('123.456,78', { mode: 'auto' })).to.equal(123456.78);
     expect(
       parseNumber('123.456,78', { mode: 'user-edited', viewValueStates: ['formatted'] }),
-    ).to.equal(123.45678);
+    ).to.equal(123456.78);
   });
 
   it('detects separators unparseable when there are 2 same ones e.g. 1.234.56', () => {