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Implement Symbol.hasInstance for MockDate #616

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Merged
merged 1 commit into from
Oct 2, 2025
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Implement Symbol.hasInstance for MockDate #616

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5 changes: 5 additions & 0 deletions .changeset/warm-ladybugs-admire.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"@ladle/react": patch
---

Fix instanceof implementation for mocked Dates
18 changes: 18 additions & 0 deletions e2e/decorators/src/mock-date.stories.tsx
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Expand Up @@ -31,3 +31,21 @@ export const Inactive: Story = () => {
</h1>
);
};

export const Instanceof: Story = () => {
const mockDate = new Date();
const realDate = new Date(1234);

return (
<dl>
<dt>mockDate instanceof Date:</dt>
<dd data-testid="mockDate">{mockDate instanceof Date ? "yes" : "no"}</dd>
<dt>realDate instanceof Date:</dt>
<dd data-testid="realDate">{realDate instanceof Date ? "yes" : "no"}</dd>
</dl>
);
};

Instanceof.meta = {
mockDate: "1995-12-17T03:24:00",
};
7 changes: 7 additions & 0 deletions e2e/decorators/tests/mock-date.spec.ts
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Expand Up @@ -25,3 +25,10 @@ test("the date is current", async ({ page }) => {
}),
);
});

test("MockDate works with instanceof", async ({ page }) => {
await page.goto("/?story=mock-date--instanceof");

await expect(page.locator('[data-testid="mockDate"]')).toHaveText("yes");
await expect(page.locator('[data-testid="realDate"]')).toHaveText("yes");
});
11 changes: 11 additions & 0 deletions e2e/decorators/tests/params.spec.ts
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Expand Up @@ -69,6 +69,17 @@ test("meta.json is correctly using defaults and overrides", async ({
name: "Inactive",
namedExport: "Inactive",
},
"mock-date--instanceof": {
filePath: "src/mock-date.stories.tsx",
levels: ["Mock date"],
locEnd: 47,
locStart: 35,
meta: {
mockDate: "1995-12-17T03:24:00",
},
name: "Instanceof",
namedExport: "Instanceof",
},
"root--examples--first": {
filePath: "src/params.stories.tsx",
levels: ["Root", "Examples"],
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4 changes: 4 additions & 0 deletions packages/ladle/lib/app/src/mock-date.ts
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Expand Up @@ -56,6 +56,10 @@ const MockDate = class Date extends RealDate {

return date;
}

static [Symbol.hasInstance](instance: unknown): boolean {
return instance instanceof RealDate;
}
};

MockDate.UTC = RealDate.UTC;
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