diff --git a/deps.testing.ts b/deps.testing.ts
new file mode 100644
index 0000000..878ad92
--- /dev/null
+++ b/deps.testing.ts
@@ -0,0 +1,6 @@
+export {
+  describe,
+  expect,
+  it,
+  mockfn,
+} from "https://js.thunderk.net/testing@1.0.0/mod.ts";
diff --git a/src/normalize.test.ts b/src/normalize.test.ts
index e69de29..0734bff 100644
--- a/src/normalize.test.ts
+++ b/src/normalize.test.ts
@@ -0,0 +1,28 @@
+import { ProjectNormalizer } from "./normalize.ts";
+import { describe, expect, it, mockfn } from "../deps.testing.ts";
+
+describe(ProjectNormalizer, () => {
+  it("uses 'deno fmt' to format path", async () => {
+    const sys = {
+      run: mockfn(() => ({
+        async status() {
+          return { success: true };
+        },
+        async output() {
+          return new TextEncoder().encode("");
+        },
+        async stderrOutput() {
+          return new TextEncoder().encode("");
+        },
+      })),
+    } as typeof Deno;
+    const normalizer = new ProjectNormalizer(sys);
+    await normalizer.formatPath("dist/test.js");
+    expect(sys.run).toHaveBeenCalledTimes(1);
+    expect(sys.run).toHaveBeenCalledWith({
+      cmd: ["./run", "fmt", "-q", "dist/test.js"],
+      stdout: "piped",
+      stderr: "piped",
+    });
+  });
+});