test: add tests

tests/unit/routes/layout.test.ts

@@ -0,0 +1,50 @@
+import { themeState } from "$states/theme.svelte";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+describe("+layout.svelte", () => {
+  beforeEach(() => {
+    themeState.theme = "dark";
+    vi.clearAllMocks();
+  });
+
+  it("should apply dark theme", () => {
+    themeState.theme = "dark";
+
+    expect(themeState.theme).toBe("dark");
+  });
+
+  it("should apply light theme", () => {
+    themeState.theme = "light";
+
+    expect(themeState.theme).toBe("light");
+  });
+
+  it("should toggle theme", () => {
+    themeState.theme = "dark";
+    themeState.toggle();
+
+    expect(themeState.theme).toBe("light");
+  });
+});
+
+import Layout from "$routes/+layout.svelte";
+import { render, screen } from "@testing-library/svelte";
+import { createRawSnippet } from "svelte";
+
+describe("Layout Component Coverage", () => {
+  it("should render children snippet and initialize props", () => {
+    const testId = "test-child";
+    const childrenSnippet = createRawSnippet(() => ({
+      render: () => `<span data-testid="${testId}">Hello</span>`,
+    }));
+
+    render(Layout, {
+      props: {
+        children: childrenSnippet,
+      },
+    });
+
+    expect(screen.getByTestId(testId)).toBeInTheDocument();
+    expect(screen.getByRole("banner")).toBeInTheDocument();
+  });
+});