Adding unit tests for donut chart (#27424)

* Adding unit tests for donut chart

* Adding unit tests for another culture

* Adding colors utility unit tests and resolving PR comments

* Rearranging test plan

packages/react-charting/docs/TestPlans/Utilities/UnitTests.md

@@ -0,0 +1,16 @@
+# Unit test plan for Donut Chart
+
+This test plan contains the list of unit testable functions which are used as a part of the Donut Chart component.
+
+Identify the functions that can be unit tested (example, functions having calculations or getting values from Utils, etc).
+
+- If required, extract the unit testable portions out of the functions which can be independently unit tested without any requirement of DOM elements.
+- Alternatively, mock the sections that cannot be unit tested.
+
+| Functions                     | Can it be unit tested | Reason                                                                                                                                                                                 |
+| ----------------------------- | --------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| a. `convertToLocaleString()`  | Yes                   |                                                                                                                                                                                        |
+| b.`getAccessibleDataObject()` | Yes                   |                                                                                                                                                                                        |
+| c. `_valueInsideDonut()`      | No                    | private function which can only be tested by rendering the donut chart component.                                                                                                      |
+| d. `wrapTextInsideDonut()`    | No                    | cannot be unit tested as it requires the tspan length to be calculated using Browser Functions like getComputedTextLength().                                                           |
+| e. `_computeTotalValue()`     | No                    | depends on the data prop passed down from the DonutChart.base to Pie during component rendering. Also since this is a private function, it can only be tested via component rendering. |

packages/react-charting/src/utilities/UtilityUnitTests.test.ts

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+import * as utils from './utilities';
+import * as colors from './colors';
+
+// Reference to the test plan: packages\react-charting\docs\TestPlans\Utilities\UnitTests.md
+
+describe('Unit test to convert data to localized string', () => {
+  test('Should return undefined when data provided is undefined', () => {
+    expect(utils.convertToLocaleString(undefined)).toBeUndefined();
+  });
+
+  test('Should return the localised data in the given culture when input data is a string', () => {
+    expect(utils.convertToLocaleString('text', 'en-GB')).toBe('text');
+    expect(utils.convertToLocaleString('text', 'ar-SY')).toBe('text');
+  });
+
+  test('Should return the localised data in the given culture when the input data is a number', () => {
+    expect(utils.convertToLocaleString(10, 'en-GB')).toBe('10');
+    expect(utils.convertToLocaleString(2560, 'ar-SY')).toBe('٢٬٥٦٠');
+  });
+
+  test('Should return the localised data when the input data is a string containing a number', () => {
+    expect(utils.convertToLocaleString('10', 'en-GB')).toBe('10');
+    expect(utils.convertToLocaleString('1234', 'ar-SY')).toBe('١٬٢٣٤');
+  });
+});
+
+describe('Unit test to return the accessible data object', () => {
+  test('Should return the appropriate accessible data object no parameters are provided as input', () => {
+    expect(utils.getAccessibleDataObject()).toEqual({
+      role: 'text',
+      'data-is-focusable': true,
+      'aria-label': undefined,
+      'aria-labelledby': undefined,
+      'aria-describedby': undefined,
+    });
+  });
+
+  test('Should return the appropriate accessible data object only role is provided as input', () => {
+    expect(utils.getAccessibleDataObject(undefined, 'button')).toEqual({
+      role: 'button',
+      'data-is-focusable': true,
+      'aria-label': undefined,
+      'aria-labelledby': undefined,
+      'aria-describedby': undefined,
+    });
+  });
+
+  test('Should return the accessible data when both role and isDataFocusable is provided as input', () => {
+    expect(utils.getAccessibleDataObject(undefined, 'text', false)).toEqual({
+      role: 'text',
+      'data-is-focusable': false,
+      'aria-label': undefined,
+      'aria-labelledby': undefined,
+      'aria-describedby': undefined,
+    });
+  });
+
+  test('Should return the appropriate accessible data object when all parameters are provided as input', () => {
+    const accessibleData = {
+      ariaLabel: 'Start button',
+      ariaLabelledBy: 'Button',
+      ariaDescribedBy: 'This is a start button',
+    };
+    expect(utils.getAccessibleDataObject(accessibleData, 'button', false)).toEqual({
+      role: 'button',
+      'data-is-focusable': false,
+      'aria-label': 'Start button',
+      'aria-labelledby': 'Button',
+      'aria-describedby': 'This is a start button',
+    });
+  });
+});
+
+describe('Unit test for getting colors from token and returning the theme specific color', () => {
+  test('Should return the token itself when the token is not from DataVizPallette', () => {
+    expect(colors.getColorFromToken('blue')).toEqual('blue');
+  });
+  test('Should return the color code when the token is from DataVizPallette', () => {
+    expect(colors.getColorFromToken('qualitative.1')).toEqual('#637cef');
+  });
+
+  test('Should return the first color when dark theme is disabled and length of colors list is more than 1', () => {
+    expect(colors.getColorFromToken('qualitative.11', false)).toEqual('#3c51b4');
+  });
+
+  test('Should return the first color when dark theme is enabled and length of colors list is equal to 1', () => {
+    expect(colors.getColorFromToken('qualitative.1', true)).toEqual('#637cef');
+  });
+
+  test('Should return the second color when dark theme is enabled and length of colors list is more than 1', () => {
+    expect(colors.getColorFromToken('qualitative.11', true)).toEqual('#93a4f4');
+  });
+});