Improve tests and docs for Deno.rename (#4597)

2 files changed, 168 insertions, 32 deletions

diff --git a/cli/js/lib.deno.ns.d.ts b/cli/js/lib.deno.ns.d.ts
index 9cef597a4..b76fac1a5 100644
--- a/cli/js/lib.deno.ns.d.ts
+++ b/cli/js/lib.deno.ns.d.ts
@@ -1284,8 +1284,10 @@ declare namespace Deno {
    *
    *       Deno.renameSync("old/path", "new/path");
    *
-   * Throws error if attempting to rename to a directory which exists and is not
-   * empty.
+   * On Unix, this operation does not follow symlinks at either path.
+   *
+   * It varies between platforms when the operation throws errors, and if so what
+   * they are. It's always an error to rename anything to a non-empty directory.
    *
    * Requires `allow-read` and `allow-write` permissions. */
   export function renameSync(oldpath: string, newpath: string): void;
@@ -1297,10 +1299,12 @@ declare namespace Deno {
    *
    *       await Deno.rename("old/path", "new/path");
    *
-   * Throws error if attempting to rename to a directory which exists and is not
-   * empty.
+   * On Unix, this operation does not follow symlinks at either path.
+   *
+   * It varies between platforms when the operation throws errors, and if so what
+   * they are. It's always an error to rename anything to a non-empty directory.
    *
-   * Requires `allow-read` and `allow-write`. */
+   * Requires `allow-read` and `allow-write` permission. */
   export function rename(oldpath: string, newpath: string): Promise<void>;
 
   /** Synchronously reads and returns the entire contents of a file as an array
diff --git a/cli/js/tests/rename_test.ts b/cli/js/tests/rename_test.ts
index 288f24bd7..45f6d709e 100644
--- a/cli/js/tests/rename_test.ts
+++ b/cli/js/tests/rename_test.ts
@@ -1,5 +1,31 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { unitTest, assert, assertEquals } from "./test_util.ts";
+import { unitTest, assert, assertEquals, assertThrows } from "./test_util.ts";
+
+function assertMissing(path: string): void {
+  let caughtErr = false;
+  let info;
+  try {
+    info = Deno.lstatSync(path);
+  } catch (e) {
+    caughtErr = true;
+    assert(e instanceof Deno.errors.NotFound);
+  }
+  assert(caughtErr);
+  assertEquals(info, undefined);
+}
+
+function assertFile(path: string): void {
+  const info = Deno.lstatSync(path);
+  assert(info.isFile());
+}
+
+function assertDirectory(path: string, mode?: number): void {
+  const info = Deno.lstatSync(path);
+  assert(info.isDirectory());
+  if (Deno.build.os !== "win" && mode !== undefined) {
+    assertEquals(info.mode! & 0o777, mode & ~Deno.umask());
+  }
+}
 
 unitTest(
   { perms: { read: true, write: true } },
@@ -9,20 +35,8 @@ unitTest(
     const newpath = testDir + "/newpath";
     Deno.mkdirSync(oldpath);
     Deno.renameSync(oldpath, newpath);
-    const newPathInfo = Deno.statSync(newpath);
-    assert(newPathInfo.isDirectory());
-
-    let caughtErr = false;
-    let oldPathInfo;
-
-    try {
-      oldPathInfo = Deno.statSync(oldpath);
-    } catch (e) {
-      caughtErr = true;
-      assert(e instanceof Deno.errors.NotFound);
-    }
-    assert(caughtErr);
-    assertEquals(oldPathInfo, undefined);
+    assertDirectory(newpath);
+    assertMissing(oldpath);
   }
 );
 
@@ -66,19 +80,137 @@ unitTest(
     const newpath = testDir + "/newpath";
     Deno.mkdirSync(oldpath);
     await Deno.rename(oldpath, newpath);
-    const newPathInfo = Deno.statSync(newpath);
-    assert(newPathInfo.isDirectory());
+    assertDirectory(newpath);
+    assertMissing(oldpath);
+  }
+);
 
-    let caughtErr = false;
-    let oldPathInfo;
+function readFileString(filename: string): string {
+  const dataRead = Deno.readFileSync(filename);
+  const dec = new TextDecoder("utf-8");
+  return dec.decode(dataRead);
+}
 
-    try {
-      oldPathInfo = Deno.statSync(oldpath);
-    } catch (e) {
-      caughtErr = true;
-      assert(e instanceof Deno.errors.NotFound);
-    }
-    assert(caughtErr);
-    assertEquals(oldPathInfo, undefined);
+function writeFileString(filename: string, s: string): void {
+  const enc = new TextEncoder();
+  const data = enc.encode(s);
+  Deno.writeFileSync(filename, data, { mode: 0o666 });
+}
+
+unitTest(
+  { ignore: Deno.build.os === "win", perms: { read: true, write: true } },
+  function renameSyncErrorsUnix(): void {
+    const testDir = Deno.makeTempDirSync();
+    const oldfile = testDir + "/oldfile";
+    const olddir = testDir + "/olddir";
+    const emptydir = testDir + "/empty";
+    const fulldir = testDir + "/dir";
+    const file = fulldir + "/file";
+    writeFileString(oldfile, "Hello");
+    Deno.mkdirSync(olddir);
+    Deno.mkdirSync(emptydir);
+    Deno.mkdirSync(fulldir);
+    writeFileString(file, "world");
+
+    assertThrows(
+      (): void => {
+        Deno.renameSync(oldfile, emptydir);
+      },
+      Error,
+      "Is a directory"
+    );
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, fulldir);
+      },
+      Error,
+      "Directory not empty"
+    );
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, file);
+      },
+      Error,
+      "Not a directory"
+    );
+
+    const fileLink = testDir + "/fileLink";
+    const dirLink = testDir + "/dirLink";
+    const danglingLink = testDir + "/danglingLink";
+    Deno.symlinkSync(file, fileLink);
+    Deno.symlinkSync(emptydir, dirLink);
+    Deno.symlinkSync(testDir + "/nonexistent", danglingLink);
+
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, fileLink);
+      },
+      Error,
+      "Not a directory"
+    );
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, dirLink);
+      },
+      Error,
+      "Not a directory"
+    );
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, danglingLink);
+      },
+      Error,
+      "Not a directory"
+    );
+
+    // should succeed on Unix
+    Deno.renameSync(olddir, emptydir);
+    Deno.renameSync(oldfile, dirLink);
+    Deno.renameSync(dirLink, danglingLink);
+    assertFile(danglingLink);
+    assertEquals("Hello", readFileString(danglingLink));
+  }
+);
+
+unitTest(
+  { ignore: Deno.build.os !== "win", perms: { read: true, write: true } },
+  function renameSyncErrorsWin(): void {
+    const testDir = Deno.makeTempDirSync();
+    const oldfile = testDir + "/oldfile";
+    const olddir = testDir + "/olddir";
+    const emptydir = testDir + "/empty";
+    const fulldir = testDir + "/dir";
+    const file = fulldir + "/file";
+    writeFileString(oldfile, "Hello");
+    Deno.mkdirSync(olddir);
+    Deno.mkdirSync(emptydir);
+    Deno.mkdirSync(fulldir);
+    writeFileString(file, "world");
+
+    assertThrows(
+      (): void => {
+        Deno.renameSync(oldfile, emptydir);
+      },
+      Deno.errors.PermissionDenied,
+      "Access is denied"
+    );
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, fulldir);
+      },
+      Deno.errors.PermissionDenied,
+      "Access is denied"
+    );
+    assertThrows(
+      (): void => {
+        Deno.renameSync(olddir, emptydir);
+      },
+      Deno.errors.PermissionDenied,
+      "Access is denied"
+    );
+
+    // should succeed on Windows
+    Deno.renameSync(olddir, file);
+    assertDirectory(file);
   }
 );