feat: add ensureSymlink/ensureSymlinkSync for fs modules (#268)

fs/README.md

@@ -45,6 +45,29 @@ ensureFile("./folder/targetFile.dat"); // returns promise
 ensureFileSync("./folder/targetFile.dat"); // void
 ```
 
+### ensureSymlink
+
+Ensures that the link exists.
+If the directory structure does not exist, it is created.
+
+```ts
+import {
+  ensureSymlink,
+  ensureSymlinkSync
+} from "https://deno.land/std/fs/mod.ts";
+
+ensureSymlink(
+  "./folder/targetFile.dat",
+  "./folder/targetFile.link.dat",
+  "file"
+); // returns promise
+ensureSymlinkSync(
+  "./folder/targetFile.dat",
+  "./folder/targetFile.link.dat",
+  "file"
+); // void
+```
+
 ### eol
 
 Detects and format the passed string for the targeted End Of Line character.

fs/ensure_symlink.ts

@@ -0,0 +1,71 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as path from "./path/mod.ts";
+import { ensureDir, ensureDirSync } from "./ensure_dir.ts";
+import { exists, existsSync } from "./exists.ts";
+import { PathType, getFileInfoType } from "./utils.ts";
+
+const isWindows = Deno.platform.os === "win";
+
+/**
+ * Ensures that the link exists.
+ * If the directory structure does not exist, it is created.
+ *
+ * @param src the source file path
+ * @param dest the destination link path
+ */
+export async function ensureSymlink(src: string, dest: string): Promise<void> {
+  const srcStatInfo = await Deno.lstat(src);
+  const srcFilePathType = getFileInfoType(srcStatInfo);
+
+  if (await exists(dest)) {
+    const destStatInfo = await Deno.lstat(dest);
+    const destFilePathType = getFileInfoType(destStatInfo);
+    if (destFilePathType !== PathType.symlink) {
+      throw new Error(
+        `Ensure path exists, expected 'symlink', got '${destFilePathType}'`
+      );
+    }
+    return;
+  }
+
+  await ensureDir(path.dirname(dest));
+
+  // TODO(axetroy): remove this if condition. refs: https://github.com/denoland/deno/issues/2169
+  if (isWindows) {
+    await Deno.symlink(src, dest, srcFilePathType || undefined);
+  } else {
+    await Deno.symlink(src, dest);
+  }
+}
+
+/**
+ * Ensures that the link exists.
+ * If the directory structure does not exist, it is created.
+ *
+ * @param src the source file path
+ * @param dest the destination link path
+ */
+export function ensureSymlinkSync(src: string, dest: string): void {
+  const srcStatInfo = Deno.lstatSync(src);
+  const srcFilePathType = getFileInfoType(srcStatInfo);
+
+  if (existsSync(dest)) {
+    const destStatInfo = Deno.lstatSync(dest);
+    const destFilePathType = getFileInfoType(destStatInfo);
+    if (destFilePathType !== PathType.symlink) {
+      throw new Error(
+        `Ensure path exists, expected 'symlink', got '${destFilePathType}'`
+      );
+    }
+    return;
+  }
+
+  ensureDirSync(path.dirname(dest));
+
+  // TODO(axetroy): remove this if condition. refs: https://github.com/denoland/deno/issues/2169
+  if (isWindows) {
+    Deno.symlinkSync(src, dest, srcFilePathType || undefined);
+  } else {
+    Deno.symlinkSync(src, dest);
+  }
+}

fs/ensure_symlink_test.ts

@@ -0,0 +1,165 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// TODO(axetroy): Add test for Windows once symlink is implemented for Windows.
+import { test } from "../testing/mod.ts";
+import {
+  assertEquals,
+  assertThrows,
+  assertThrowsAsync
+} from "../testing/asserts.ts";
+import { ensureSymlink, ensureSymlinkSync } from "./ensure_symlink.ts";
+import * as path from "./path/mod.ts";
+
+const testdataDir = path.resolve("fs", "testdata");
+const isWindows = Deno.platform.os === "win";
+
+test(async function ensureSymlinkIfItNotExist() {
+  const testDir = path.join(testdataDir, "link_file_1");
+  const testFile = path.join(testDir, "test.txt");
+
+  assertThrowsAsync(async () => {
+    await ensureSymlink(testFile, path.join(testDir, "test1.txt"));
+  });
+
+  assertThrowsAsync(async () => {
+    await Deno.stat(testFile).then(() => {
+      throw new Error("test file should exists.");
+    });
+  });
+});
+
+test(function ensureSymlinkSyncIfItNotExist() {
+  const testDir = path.join(testdataDir, "link_file_2");
+  const testFile = path.join(testDir, "test.txt");
+
+  assertThrows(() => {
+    ensureSymlinkSync(testFile, path.join(testDir, "test1.txt"));
+  });
+
+  assertThrows(() => {
+    Deno.statSync(testFile);
+    throw new Error("test file should exists.");
+  });
+});
+
+test(async function ensureSymlinkIfItExist() {
+  const testDir = path.join(testdataDir, "link_file_3");
+  const testFile = path.join(testDir, "test.txt");
+  const linkFile = path.join(testDir, "link.txt");
+
+  await Deno.mkdir(testDir, true);
+  await Deno.writeFile(testFile, new Uint8Array());
+
+  if (isWindows) {
+    await assertThrowsAsync(
+      () => ensureSymlink(testFile, linkFile),
+      Error,
+      "Not implemented"
+    );
+    await Deno.remove(testDir, { recursive: true });
+    return;
+  } else {
+    await ensureSymlink(testFile, linkFile);
+  }
+
+  const srcStat = await Deno.lstat(testFile);
+  const linkStat = await Deno.lstat(linkFile);
+
+  assertEquals(srcStat.isFile(), true);
+  assertEquals(linkStat.isSymlink(), true);
+
+  await Deno.remove(testDir, { recursive: true });
+});
+
+test(function ensureSymlinkSyncIfItExist() {
+  const testDir = path.join(testdataDir, "link_file_4");
+  const testFile = path.join(testDir, "test.txt");
+  const linkFile = path.join(testDir, "link.txt");
+
+  Deno.mkdirSync(testDir, true);
+  Deno.writeFileSync(testFile, new Uint8Array());
+
+  if (isWindows) {
+    assertThrows(
+      () => ensureSymlinkSync(testFile, linkFile),
+      Error,
+      "Not implemented"
+    );
+    Deno.removeSync(testDir, { recursive: true });
+    return;
+  } else {
+    ensureSymlinkSync(testFile, linkFile);
+  }
+
+  const srcStat = Deno.lstatSync(testFile);
+
+  const linkStat = Deno.lstatSync(linkFile);
+
+  assertEquals(srcStat.isFile(), true);
+  assertEquals(linkStat.isSymlink(), true);
+
+  Deno.removeSync(testDir, { recursive: true });
+});
+
+test(async function ensureSymlinkDirectoryIfItExist() {
+  const testDir = path.join(testdataDir, "link_file_origin_3");
+  const linkDir = path.join(testdataDir, "link_file_link_3");
+  const testFile = path.join(testDir, "test.txt");
+
+  await Deno.mkdir(testDir, true);
+  await Deno.writeFile(testFile, new Uint8Array());
+
+  if (isWindows) {
+    await assertThrowsAsync(
+      () => ensureSymlink(testDir, linkDir),
+      Error,
+      "Not implemented"
+    );
+    await Deno.remove(testDir, { recursive: true });
+    return;
+  } else {
+    await ensureSymlink(testDir, linkDir);
+  }
+
+  const testDirStat = await Deno.lstat(testDir);
+  const linkDirStat = await Deno.lstat(linkDir);
+  const testFileStat = await Deno.lstat(testFile);
+
+  assertEquals(testFileStat.isFile(), true);
+  assertEquals(testDirStat.isDirectory(), true);
+  assertEquals(linkDirStat.isSymlink(), true);
+
+  await Deno.remove(linkDir, { recursive: true });
+  await Deno.remove(testDir, { recursive: true });
+});
+
+test(function ensureSymlinkSyncDirectoryIfItExist() {
+  const testDir = path.join(testdataDir, "link_file_origin_3");
+  const linkDir = path.join(testdataDir, "link_file_link_3");
+  const testFile = path.join(testDir, "test.txt");
+
+  Deno.mkdirSync(testDir, true);
+  Deno.writeFileSync(testFile, new Uint8Array());
+
+  if (isWindows) {
+    assertThrows(
+      () => ensureSymlinkSync(testDir, linkDir),
+      Error,
+      "Not implemented"
+    );
+    Deno.removeSync(testDir, { recursive: true });
+    return;
+  } else {
+    ensureSymlinkSync(testDir, linkDir);
+  }
+
+  const testDirStat = Deno.lstatSync(testDir);
+  const linkDirStat = Deno.lstatSync(linkDir);
+  const testFileStat = Deno.lstatSync(testFile);
+
+  assertEquals(testFileStat.isFile(), true);
+  assertEquals(testDirStat.isDirectory(), true);
+  assertEquals(linkDirStat.isSymlink(), true);
+
+  Deno.removeSync(linkDir, { recursive: true });
+  Deno.removeSync(testDir, { recursive: true });
+});

fs/test.ts

@@ -8,6 +8,7 @@ import "./eol_test.ts";
 import "./empty_dir_test.ts";
 import "./ensure_dir_test.ts";
 import "./ensure_file_test.ts";
+import "./ensure_symlink_test.ts";
 import "./move_test.ts";
 import "./read_json_test.ts";
 import "./write_json_test.ts";