40 lines
1.6 KiB
TypeScript
40 lines
1.6 KiB
TypeScript
// Prüfung: Kontrastwerte erfüllen mindestens AA (SHL-01 Prüfung 3 / Akzeptanzkriterium 4).
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import { describe, expect, it } from "vitest";
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import { colorTokens } from "../tokens/tokens";
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// WCAG-2.1-AA-Kontrastberechnung (relative Luminanz, sRGB) — keine externe Abhängigkeit nötig.
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function relLuminance(hex: string): number {
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const rgb = [1, 3, 5].map((i) => parseInt(hex.slice(i, i + 2), 16) / 255);
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const [r, g, b] = rgb.map((c) => (c <= 0.03928 ? c / 12.92 : ((c + 0.055) / 1.055) ** 2.4));
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return 0.2126 * r + 0.7152 * g + 0.0722 * b;
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}
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function contrastRatio(a: string, b: string): number {
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const l1 = relLuminance(a);
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const l2 = relLuminance(b);
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const [lighter, darker] = l1 > l2 ? [l1, l2] : [l2, l1];
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return (lighter + 0.05) / (darker + 0.05);
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}
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describe("Design-Tokens: WCAG 2.1 AA Kontrast", () => {
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for (const scheme of ["light", "dark"] as const) {
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const c = colorTokens[scheme];
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it(`${scheme}: textPrimary auf background erfüllt AA (>= 4.5:1)`, () => {
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expect(contrastRatio(c.textPrimary, c.background)).toBeGreaterThanOrEqual(4.5);
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});
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it(`${scheme}: textSecondary auf surface erfüllt AA (>= 4.5:1)`, () => {
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expect(contrastRatio(c.textSecondary, c.surface)).toBeGreaterThanOrEqual(4.5);
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});
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it(`${scheme}: accentContrast auf accent erfüllt AA (>= 4.5:1)`, () => {
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expect(contrastRatio(c.accentContrast, c.accent)).toBeGreaterThanOrEqual(4.5);
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});
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it(`${scheme}: dangerContrast auf danger erfüllt AA (>= 4.5:1)`, () => {
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expect(contrastRatio(c.dangerContrast, c.danger)).toBeGreaterThanOrEqual(4.5);
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});
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}
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});
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