feat(M4): Reusable code abstractions and dead-code removal

2026-05-03 21:45:49 -05:00
parent 86ad783f82
commit 7495020a9c
98 changed files with 1696 additions and 950 deletions
@@ -0,0 +1,139 @@
+import assert from "node:assert/strict";
+import { mkdtemp, mkdir, writeFile, readFile, readdir, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import test from "node:test";
+
+import { safeReplaceDir } from "../lib/safe-replace-dir.mjs";
+
+// ── Happy path ────────────────────────────────────────────────────────────
+
+test("safeReplaceDir copies source content into the target", async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), "safe-replace-copy-"));
+  try {
+    const safetyRoot = path.join(dir, "root");
+    const source = path.join(dir, "source");
+    const target = path.join(safetyRoot, "target");
+
+    await mkdir(source, { recursive: true });
+    await writeFile(path.join(source, "file.txt"), "hello");
+    await mkdir(safetyRoot, { recursive: true });
+
+    await safeReplaceDir(source, target, safetyRoot);
+
+    const content = await readFile(path.join(target, "file.txt"), "utf8");
+    assert.equal(content, "hello");
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("safeReplaceDir removes existing content before replacing", async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), "safe-replace-stale-"));
+  try {
+    const safetyRoot = path.join(dir, "root");
+    const source = path.join(dir, "source");
+    const target = path.join(safetyRoot, "target");
+
+    await mkdir(target, { recursive: true });
+    await writeFile(path.join(target, "old.txt"), "stale");
+    await mkdir(source, { recursive: true });
+    await writeFile(path.join(source, "new.txt"), "fresh");
+
+    await safeReplaceDir(source, target, safetyRoot);
+
+    const files = await readdir(target);
+    assert.deepEqual(files.sort(), ["new.txt"]);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("safeReplaceDir creates target parent directories if they do not exist", async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), "safe-replace-mkdir-"));
+  try {
+    const safetyRoot = path.join(dir, "root");
+    const source = path.join(dir, "source");
+    const target = path.join(safetyRoot, "nested", "target");
+
+    await mkdir(source, { recursive: true });
+    await writeFile(path.join(source, "data.txt"), "data");
+    await mkdir(safetyRoot, { recursive: true });
+    // nested parent does NOT exist yet
+
+    await safeReplaceDir(source, target, safetyRoot);
+
+    const content = await readFile(path.join(target, "data.txt"), "utf8");
+    assert.equal(content, "data");
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("safeReplaceDir creates deeply nested parent directories (2+ levels missing)", async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), "safe-replace-deep-"));
+  try {
+    const safetyRoot = path.join(dir, "root");
+    const source = path.join(dir, "source");
+    // two parent levels (a/b) do NOT exist under safetyRoot
+    const target = path.join(safetyRoot, "a", "b", "target");
+
+    await mkdir(source, { recursive: true });
+    await writeFile(path.join(source, "deep.txt"), "deep");
+    await mkdir(safetyRoot, { recursive: true });
+    // a/ and a/b/ intentionally NOT created
+
+    await safeReplaceDir(source, target, safetyRoot);
+
+    const content = await readFile(path.join(target, "deep.txt"), "utf8");
+    assert.equal(content, "deep");
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+// ── Safety checks ─────────────────────────────────────────────────────────
+
+test("safeReplaceDir refuses when target is outside the safety root", async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), "safe-replace-outside-"));
+  try {
+    const safetyRoot = path.join(dir, "root");
+    const source = path.join(dir, "source");
+    const outside = path.join(dir, "outside");
+
+    await mkdir(source, { recursive: true });
+    await mkdir(safetyRoot, { recursive: true });
+
+    await assert.rejects(
+      () => safeReplaceDir(source, outside, safetyRoot),
+      /outside safety root/,
+    );
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("safeReplaceDir refuses when target equals the safety root", async () => {
+  const dir = await mkdtemp(path.join(tmpdir(), "safe-replace-same-"));
+  try {
+    const safetyRoot = path.join(dir, "root");
+    const source = path.join(dir, "source");
+
+    await mkdir(source, { recursive: true });
+    await mkdir(safetyRoot, { recursive: true });
+
+    await assert.rejects(
+      () => safeReplaceDir(source, safetyRoot, safetyRoot),
+      /outside safety root/,
+    );
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("safeReplaceDir refuses an empty target string", async () => {
+  await assert.rejects(
+    () => safeReplaceDir("/any", "", "/root"),
+    /unsafe target/,
+  );
+});