fix(date, date-range): ensure date format override returns correct formatted value

src/components/date-range/date-range.component.tsx

@@ -149,6 +149,7 @@ export const DateRange = ({
   endRef,
   required,
   isOptional,
+  dateFormatOverride: dateFormatOverrideProp,
   datePickerStartAriaLabel,
   datePickerStartAriaLabelledBy,
   datePickerEndAriaLabel,
@@ -169,8 +170,12 @@ export const DateRange = ({
   const l = useLocale();
   const { dateFnsLocale, dateFormatOverride } = l.date;
   const { format } = useMemo(
-    () => getFormatData(dateFnsLocale(), dateFormatOverride),
-    [dateFnsLocale, dateFormatOverride],
+    () =>
+      getFormatData(
+        dateFnsLocale(),
+        dateFormatOverrideProp || dateFormatOverride,
+      ),
+    [dateFnsLocale, dateFormatOverrideProp, dateFormatOverride],
   );
   const inlineLabelWidth = 40;
   const [lastChangedDate, setLastChangedDate] = useState("");

src/components/date-range/date-range.test.tsx

@@ -2,7 +2,6 @@ import React from "react";
 import { render, screen, within } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import { enGB as enGBLocale } from "date-fns/locale/en-GB";
-import { de as deLocale } from "date-fns/locale/de";
 
 import DateRange, { DateRangeChangeEvent } from "./date-range.component";
 import { testStyledSystemMargin } from "../../__spec_helper__/__internal__/test-utils";
@@ -1219,17 +1218,17 @@ test("should have the default styling when the `labelsInline` prop is set and `v
 });
 
 describe("Locale formatting overrides", () => {
-  test("should render with the input value matching the expected format when `dateFormatOverride` is set and the language is `de-DE`", () => {
+  it("should render with the input value matching the expected format when `dateFormatOverride` is passed as a translation key", () => {
     render(
       <I18nProvider
         locale={{
-          locale: () => "de-DE",
+          locale: () => "en-GB",
           date: {
             ariaLabels: {
               nextMonthButton: () => "foo",
               previousMonthButton: () => "foo",
             },
-            dateFnsLocale: () => deLocale,
+            dateFnsLocale: () => enGBLocale,
             dateFormatOverride: "y-m-ddd",
           },
         }}
@@ -1251,28 +1250,15 @@ describe("Locale formatting overrides", () => {
     );
   });
 
-  test("should render with the input value matching the expected format when `dateFormatOverride` is set and the language is `en-GB`", () => {
+  it("should render with the input value matching the expected format when `dateFormatOverride` is passed as a prop", () => {
     render(
-      <I18nProvider
-        locale={{
-          locale: () => "en-GB",
-          date: {
-            ariaLabels: {
-              nextMonthButton: () => "foo",
-              previousMonthButton: () => "foo",
-            },
-            dateFnsLocale: () => enGBLocale,
-            dateFormatOverride: "y-m-ddd",
-          },
-        }}
-      >
-        <DateRange
-          startLabel="start"
-          endLabel="end"
-          value={["2016-10-10", "2016-11-11"]}
-          onChange={() => {}}
-        />
-      </I18nProvider>,
+      <DateRange
+        startLabel="start"
+        endLabel="end"
+        value={["2016-10-10", "2016-11-11"]}
+        onChange={() => {}}
+        dateFormatOverride="y-m-ddd"
+      />,
     );
 
     expect(screen.getByRole("textbox", { name: "start" })).toHaveValue(

src/components/date/__internal__/date-formats/date-formats.test.ts

@@ -511,39 +511,65 @@ test("should default to en-GB locale if no locale code string passed to `getForm
 });
 
 describe("dateFormatOverride tests", () => {
-  const localeCodes = [
-    // handled locales
-    "en-CA",
-    "en-US",
-    "en-ZA",
-    "fr-CA",
-    "ar-EG",
-    // random locale to cover default switch scenario
-    "zh-HK",
-  ];
-  const dateFormatOverride = "dd Mo yyyy";
-
-  test.each(localeCodes)(
-    "should support %s locale code string passed to `getFormatData` when dateFormatOverride is provided",
-    (code: string) => {
-      const { formats, format } = getFormatData({ code }, dateFormatOverride);
-
-      const expectedFormats = getExpectedFormatForLocale(code);
-
-      expect(
-        expectedFormats.every((formatStr) => formats.includes(formatStr)) &&
-          formats.length === expectedFormats.length,
-      ).toEqual(true);
-
-      expect(format).toEqual(dateFormatOverride);
-    },
-  );
+  it("should return the expected formats when `dateFormatOverride` is passed as NA locale", () => {
+    const dateFormatOverride = "MM/dd/yyyy";
+    const { formats, format } = getFormatData(
+      { code: "en-GB" },
+      dateFormatOverride,
+    );
+
+    // since the dateFormatOverride starts with the month, it should be treated as a NA locale
+    const expectedFormats = getExpectedFormatForLocale("en-US");
+
+    expect(
+      expectedFormats.every((formatStr) => formats.includes(formatStr)) &&
+        formats.length === expectedFormats.length,
+    ).toEqual(true);
+
+    expect(format).toEqual(dateFormatOverride);
+  });
+
+  it("should return the expected formats when `dateFormatOverride` is passed as EU locale", () => {
+    const dateFormatOverride = "dd/MM/yyyy";
+    const { formats, format } = getFormatData(
+      { code: "en-US" },
+      dateFormatOverride,
+    );
+
+    // since the dateFormatOverride starts with the day, it should be treated as a EU locale
+    const expectedFormats = getExpectedFormatForLocale("en-GB");
+
+    expect(
+      expectedFormats.every((formatStr) => formats.includes(formatStr)) &&
+        formats.length === expectedFormats.length,
+    ).toEqual(true);
+
+    expect(format).toEqual(dateFormatOverride);
+  });
+
+  it("should return the expected formats when `dateFormatOverride` is passed as CN locale", () => {
+    const dateFormatOverride = "yyyy/MM/dd";
+    const { formats, format } = getFormatData(
+      { code: "en-GB" },
+      dateFormatOverride,
+    );
+
+    // since the dateFormatOverride starts with the year, it should be treated as a CN locale
+    const expectedFormats = getExpectedFormatForLocale("zh");
+
+    expect(
+      expectedFormats.every((formatStr) => formats.includes(formatStr)) &&
+        formats.length === expectedFormats.length,
+    ).toEqual(true);
+
+    expect(format).toEqual(dateFormatOverride);
+  });
 });
 
 describe.each(euLocales)(
   "when EU locales are passed to `getFormatData`",
   (locale: string) => {
-    test(`should return the expected object shape for ${locale} locale`, () => {
+    it(`should return the expected object shape for ${locale} locale`, () => {
       const { formats } = getFormatData({ code: locale });
 
       const expectedFormats = getExpectedFormatForLocale(locale);
@@ -559,7 +585,7 @@ describe.each(euLocales)(
 describe.each(naLocales)(
   "when NA locales are passed to `getFormatData`",
   (locale: string) => {
-    test(`should return the expected object shape for ${locale} locale`, () => {
+    it(`should return the expected object shape for ${locale} locale`, () => {
       const { formats } = getFormatData({ code: locale });
 
       const expectedFormats = getExpectedFormatForLocale(locale);
@@ -575,7 +601,7 @@ describe.each(naLocales)(
 describe.each(cnLocales)(
   "when CN locales are passed to `getFormatData`",
   (locale: string) => {
-    test(`should return the expected object shape for ${locale} locale`, () => {
+    it(`should return the expected object shape for ${locale} locale`, () => {
       const { formats } = getFormatData({ code: locale });
 
       const expectedFormats = getExpectedFormatForLocale(locale);

src/components/date/__internal__/date-formats/index.ts

@@ -145,51 +145,30 @@ const getFormatData = (
   dateFormatOverride?: string,
 ): LocaleFormats => {
   const code = locale?.code || "en-GB";
-  if (dateFormatOverride) {
-    const { format } = getOutputFormatForLocale(code);
-    let formatFromLocale;
-
-    switch (code) {
-      case "en-CA":
-      case "en-US":
-        formatFromLocale = "MM/dd/yyyy";
-        break;
-      case "ar-EG":
-      case "en-ZA":
-      case "fr-CA":
-        formatFromLocale = "dd/MM/yyyy";
-        break;
-      default:
-        formatFromLocale = format;
-    }
 
-    const formatsForLocale = getInputFormatsArrayForLocale(formatFromLocale);
+  const dateFnsFormatOverrides: Record<
+    string,
+    { format: string; separator?: Separator }
+  > = {
+    "en-CA": { format: "MM/dd/yyyy", separator: "/" },
+    "en-US": { format: "MM/dd/yyyy", separator: "/" },
+    "fr-CA": { format: "dd/MM/yyyy" },
+    "en-ZA": { format: "dd/MM/yyyy" },
+    "ar-EG": { format: "dd/MM/yyyy" },
+  };
 
-    return {
-      format: dateFormatOverride,
-      formats: generateFormats(formatsForLocale, "/"),
-    };
-  }
+  const { format: defaultFormat, separator: defaultSeparator } =
+    getOutputFormatForLocale(code);
 
-  if (["en-CA", "en-US"].includes(code)) {
-    const format = "MM/dd/yyyy";
-    const formats = getInputFormatsArrayForLocale(format);
-    return {
-      format,
-      formats: generateFormats(formats, "/"),
-    };
-  }
+  const override = dateFnsFormatOverrides[code] || {};
 
-  const { format, separator } = getOutputFormatForLocale(code);
-  const outputFormat = ["fr-CA", "en-ZA", "ar-EG"].includes(code)
-    ? "dd/MM/yyyy"
-    : format;
-  const formatsForLocale = getInputFormatsArrayForLocale(outputFormat);
+  const format = dateFormatOverride ?? override.format ?? defaultFormat;
+  const separator = override.separator ?? defaultSeparator;
 
   return {
-    format: outputFormat,
+    format,
     formats: generateFormats(
-      formatsForLocale,
+      getInputFormatsArrayForLocale(format),
       separator,
       getTrailingChar(format),
     ),