test: cover filesystem interface contract (#245)

Signed-off-by: EfeDurmaz16 <efebarandurmaz05@gmail.com>

Author: EfeDurmaz16

packages/just-bash/src/fs/interface.contract.test.ts

@@ -0,0 +1,72 @@
+import { describe, expect, it } from "vitest";
+import { InMemoryFs } from "./in-memory-fs/in-memory-fs.js";
+
+describe("IFileSystem contract", () => {
+  it("reads, writes, appends, stats, lists, and removes files", async () => {
+    const fs = new InMemoryFs();
+
+    await fs.mkdir("/docs", { recursive: true });
+    await fs.writeFile("/docs/readme.md", "hello");
+    await fs.appendFile("/docs/readme.md", " world");
+
+    expect(await fs.readFile("/docs/readme.md")).toBe("hello world");
+    expect(await fs.exists("/docs/readme.md")).toBe(true);
+    expect((await fs.stat("/docs/readme.md")).isFile).toBe(true);
+    expect(await fs.readdir("/docs")).toContain("readme.md");
+
+    await fs.rm("/docs/readme.md");
+    expect(await fs.exists("/docs/readme.md")).toBe(false);
+  });
+
+  it("copies and moves files without changing file contents", async () => {
+    const fs = new InMemoryFs();
+
+    await fs.mkdir("/tmp", { recursive: true });
+    await fs.writeFile("/tmp/source.txt", "contents");
+    await fs.cp("/tmp/source.txt", "/tmp/copy.txt");
+    await fs.mv("/tmp/copy.txt", "/tmp/moved.txt");
+
+    expect(await fs.readFile("/tmp/source.txt")).toBe("contents");
+    expect(await fs.readFile("/tmp/moved.txt")).toBe("contents");
+    expect(await fs.exists("/tmp/copy.txt")).toBe(false);
+  });
+
+  it("rejects null-byte paths for mutating and read operations", async () => {
+    const fs = new InMemoryFs();
+
+    await expect(fs.readFile("/evil\0.txt")).rejects.toThrow("null byte");
+    await expect(fs.writeFile("/evil\0.txt", "data")).rejects.toThrow(
+      "null byte",
+    );
+    await expect(fs.mkdir("/evil\0dir")).rejects.toThrow("null byte");
+    await expect(fs.rm("/evil\0.txt")).rejects.toThrow("null byte");
+  });
+
+  it("clamps traversal above the virtual root", async () => {
+    const fs = new InMemoryFs();
+
+    await fs.writeFile("/root.txt", "root");
+
+    expect(await fs.readFile("/../../root.txt")).toBe("root");
+    expect((await fs.stat("/../../")).isDirectory).toBe(true);
+  });
+
+  it("resolves relative paths consistently", () => {
+    const fs = new InMemoryFs();
+
+    expect(fs.resolvePath("/work", "file.txt")).toBe("/work/file.txt");
+    expect(fs.resolvePath("/work", "../file.txt")).toBe("/file.txt");
+    expect(fs.resolvePath("/work", "/absolute.txt")).toBe("/absolute.txt");
+  });
+
+  it("creates symlinks and keeps absolute symlink targets virtual", async () => {
+    const fs = new InMemoryFs();
+
+    await fs.writeFile("/target.txt", "target");
+    await fs.symlink("/target.txt", "/link.txt");
+
+    expect(await fs.readlink("/link.txt")).toBe("/target.txt");
+    expect((await fs.lstat("/link.txt")).isSymbolicLink).toBe(true);
+    expect(await fs.readFile("/link.txt")).toBe("target");
+  });
+});