Treat "initial" as black for border color

[juliaroldi]

When pasting a table that has border color set to "initial", use black as default color. Otherwise, the table border color handler will treat the table as it has no border color.

[Copilot]

Pull request overview

This PR adjusts table border color parsing so that when pasted content uses the CSS keyword initial for a border color, the system treats it as a concrete default color (black) instead of effectively “no color”, preserving intended borders during paste/transform.

Changes:

• Default border*-color: initial to #000000 during borderColorFormatHandler.parse().
• Refactor apply() slightly to reuse the computed border color property key.
• Add a unit test covering the new initial parsing behavior (light mode).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/roosterjs-content-model-dom/lib/formatHandlers/common/borderColorFormatHandler.ts	Adds defaulting behavior for initial border color and minor apply refactor.
packages/roosterjs-content-model-dom/test/formatHandlers/common/borderColorFormatHandlerTest.ts	Adds a parse test asserting initial becomes black.

Comments suppressed due to low confidence (1)

packages/roosterjs-content-model-dom/lib/formatHandlers/common/borderColorFormatHandler.ts:53

• When context.isDarkMode is true and a darkColorHandler is present, getLightModeColor('#000000', true, handler) can return an empty string (it treats unknown non-var colors as potentially dark colors and drops them). For the 'initial' case this would defeat the intent (defaulting to black) and may result in a border value without a color. Consider bypassing getLightModeColor for the 'initial' keyword (or call it with isDarkMode=false/without darkColorHandler) so the default black is preserved regardless of current mode.

                const color = retrieveElementColor(element, key);
                const borderColor = color == 'initial' ? DEFAULT_COLOR : color;

                if (borderColor) {
                    const lightModeColor = getLightModeColor(
                        borderColor,
                        !!context.isDarkMode,
                        context.darkColorHandler
                    );

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[Copilot]

The new "initial" parsing behavior is only covered in light mode. Adding a dark-mode test (with context.isDarkMode = true and a darkColorHandler present) would help catch regressions where the default black gets dropped/altered by getLightModeColor logic in dark mode.

Suggested change

	});
	});
	it('Parse border with initial color in dark mode - should use default color', () => {
	div.style.borderWidth = '1px';
	div.style.borderStyle = 'solid';
	div.style.borderTopColor = 'initial';
	const mockDarkColorHandler = {
	knownColors: {},
	getDarkColor: jasmine.createSpy('getDarkColor').and.returnValue('#000000'),
	updateKnownColor: jasmine.createSpy('updateKnownColor'),
	generateColorKey: jasmine.createSpy('generateColorKey').and.returnValue('--colorKeyInitial'),
	reset: jasmine.createSpy('reset'),
	};
	context.isDarkMode = true;
	context.darkColorHandler = mockDarkColorHandler;
	spyOn(colorUtils, 'retrieveElementColor').and.returnValue('initial');
	spyOn(colorUtils, 'getLightModeColor').and.returnValue('#000000');
	borderColorFormatHandler.parse(format, div, context, {});
	expect(colorUtils.retrieveElementColor).toHaveBeenCalledWith(div, 'borderTop');
	expect(colorUtils.getLightModeColor).toHaveBeenCalledWith(
	'#000000',
	true,
	mockDarkColorHandler
	);
	expect(format.borderTop).toBe('1px solid #000000');
	});