Refactor Study Desk application structure

tests/helpers/testDatabase.test.ts

@@ -0,0 +1,41 @@
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+import { assertDisposableTestDatabase } from "./testDatabase";
+
+const cleanup: string[] = [];
+
+afterEach(() => {
+  for (const directory of cleanup.splice(0)) {
+    rmSync(directory, { recursive: true, force: true });
+  }
+});
+
+describe("assertDisposableTestDatabase", () => {
+  it("accepts a new uniquely named test database", () => {
+    const directory = mkdtempSync(path.join(tmpdir(), "study-db-safety-"));
+    cleanup.push(directory);
+    const target = path.join(directory, "unique.test.db");
+    expect(assertDisposableTestDatabase(`file:${target}`)).toBe(path.resolve(target));
+  });
+
+  it.each(["file:./dev.db", "file:/app/data/study.db"])(
+    "rejects protected database path %s",
+    (databaseUrl) => {
+      expect(() => assertDisposableTestDatabase(databaseUrl)).toThrow(
+        "Refusing to use non-disposable database"
+      );
+    }
+  );
+
+  it("rejects an existing database even when its name looks like a test", () => {
+    const directory = mkdtempSync(path.join(tmpdir(), "study-db-safety-"));
+    cleanup.push(directory);
+    const target = path.join(directory, "existing.test.db");
+    writeFileSync(target, "not disposable");
+    expect(() => assertDisposableTestDatabase(`file:${target}`)).toThrow(
+      "Refusing to use non-disposable database"
+    );
+  });
+});