feat: add dirname functions to return a directory name

This is useful when you don't want to create a directory with vitest-testdirs, but just want to generate a path that you can be created by something else.

Author: luxass

src/index.ts

@@ -27,7 +27,6 @@ import {
 } from "node:fs/promises";
 import {
   dirname,
-  join,
   normalize,
   sep as pathSeparator,
   resolve,
@@ -42,7 +41,7 @@ import {
 } from "vitest/suite";
 import { BASE_DIR, FIXTURE_METADATA_SYMBOL, FIXTURE_ORIGINAL_PATH_SYMBOL } from "./constants";
 import { hasMetadata, isLink, isPrimitive, isSymlink } from "./helpers";
-import { createDirnameFromTask, isDirectory, isDirectorySync, isInVitest, processDirectory, processDirectorySync } from "./utils";
+import { internalGenerateDirname, isDirectory, isDirectorySync, isInVitest, processDirectory, processDirectorySync } from "./utils";
 
 export * from "./constants";
 export * from "./helpers";
@@ -96,11 +95,7 @@ export async function testdir(
   const test = getCurrentTest();
   const suite = getCurrentSuite();
 
-  const dirname = options?.dirname
-    ? normalize(join(BASE_DIR, options.dirname))
-    : normalize(join(BASE_DIR, createDirnameFromTask(
-        (test?.type === "test" ? test : suite) || suite,
-      )));
+  const dirname = internalGenerateDirname(options?.dirname);
 
   const allowOutside = options?.allowOutside ?? false;
 
@@ -134,6 +129,24 @@ export async function testdir(
   return dirname;
 }
 
+/**
+ * Generates the path for a test directory.
+ *
+ * @param {string?} dirname - The directory name to use.
+ *
+ * If not provided, a directory name will be generated based on the test name.
+ *
+ * @returns {string} The path of the current test directory.
+ * @throws An error if `testdir` is called outside of a test.
+ */
+testdir.dirname = (dirname?: string): string => {
+  if (!isInVitest()) {
+    throw new Error("testdir must be called inside vitest context");
+  }
+
+  return internalGenerateDirname(dirname);
+};
+
 /**
  * Creates a test directory with the specified files and options.
  *
@@ -153,11 +166,7 @@ export function testdirSync(
   const test = getCurrentTest();
   const suite = getCurrentSuite();
 
-  const dirname = options?.dirname
-    ? normalize(join(BASE_DIR, options.dirname))
-    : normalize(join(BASE_DIR, createDirnameFromTask(
-        (test?.type === "test" ? test : suite) || suite,
-      )));
+  const dirname = internalGenerateDirname(options?.dirname);
 
   const allowOutside = options?.allowOutside ?? false;
 
@@ -191,6 +200,24 @@ export function testdirSync(
   return dirname;
 }
 
+/**
+ * Generates the path for a test directory.
+ *
+ * @param {string?} dirname - The directory name to use.
+ *
+ * If not provided, a directory name will be generated based on the test name.
+ *
+ * @returns {string} The path of the current test directory.
+ * @throws An error if `testdir` is called outside of a test.
+ */
+testdirSync.dirname = (dirname?: string): string => {
+  if (!isInVitest()) {
+    throw new Error("testdirSync must be called inside vitest context");
+  }
+
+  return internalGenerateDirname(dirname);
+};
+
 /**
  * Creates a file tree at the specified path using the provided files object.
  * The files object represents the directory structure and file contents of the tree.

src/utils.ts

@@ -1,11 +1,12 @@
 import type { DirectoryJSON, FromFileSystemOptions } from "./types";
 import { readdirSync, readFileSync, readlinkSync, statSync } from "node:fs";
 import { readdir, readFile, readlink, stat } from "node:fs/promises";
-import { normalize } from "node:path";
+import { join, normalize } from "node:path";
 import process from "node:process";
 import { expect, type RunnerTask, type SuiteCollector } from "vitest";
 import { getCurrentSuite, getCurrentTest } from "vitest/suite";
 import {
+  BASE_DIR,
   FIXTURE_ORIGINAL_PATH_SYMBOL,
 } from "./constants";
 import { symlink } from "./helpers";
@@ -210,3 +211,24 @@ export function processDirectorySync(
 
   return files;
 }
+
+/**
+ * Generates a normalized directory path based on the provided dirname or the current test/suite context.
+ * This function must be called within a Vitest context.
+ *
+ * @param {string?} dirname - Optional directory name to use as the base path
+ * @returns {string} A normalized absolute path combining the base directory with either the provided dirname or a generated name from the current test/suite
+ * @internal
+ */
+export function internalGenerateDirname(dirname?: string): string {
+  const test = getCurrentTest();
+  const suite = getCurrentSuite();
+
+  if (dirname != null) {
+    return normalize(join(BASE_DIR, dirname));
+  }
+
+  return normalize(join(BASE_DIR, createDirnameFromTask(
+    (test?.type === "test" ? test : suite) || suite,
+  )));
+}