Allow setting a prefix for temp directory

index.d.ts

@@ -2,7 +2,7 @@
 import {MergeExclusive, TypedArray} from 'type-fest';
 
 declare namespace tempy {
-	type Options = MergeExclusive<
+	type FileOptions = MergeExclusive<
 		{
 			/**
 			File extension.
@@ -24,6 +24,17 @@ declare namespace tempy {
 			readonly name?: string;
 		}
 	>;
+
+	type DirectoryOptions = {
+		/**
+		_You usually won't need this option. Specify it only when actually needed._
+
+		Directory prefix.
+
+		Useful for testing by making it easier to identify cache directories that are created.
+		*/
+		readonly prefix?: string;
+	}
 }
 
 declare const tempy: {
@@ -47,7 +58,7 @@ declare const tempy: {
 	//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/2f3d094aec2cb1b93bb0f4cffce5ebd6'
 	```
 	*/
-	file(options?: tempy.Options): string;
+	file(options?: tempy.FileOptions): string;
 
 	/**
 	Get a temporary directory path. The directory is created for you.
@@ -58,9 +69,12 @@ declare const tempy: {
 
 	tempy.directory();
 	//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/2f3d094aec2cb1b93bb0f4cffce5ebd6'
+
+	tempy.directory({prefix: 'a'});
+	//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/name_3c085674ad31223b9653c88f725d6b41'
 	```
 	*/
-	directory(): string;
+	directory(options?: tempy.DirectoryOptions): string;
 
 	/**
 	Write data to a random temp file.
@@ -73,7 +87,7 @@ declare const tempy: {
 	//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/2f3d094aec2cb1b93bb0f4cffce5ebd6'
 	```
 	*/
-	write(fileContent: string | Buffer | TypedArray | DataView | NodeJS.ReadableStream, options?: tempy.Options): Promise<string>;
+	write(fileContent: string | Buffer | TypedArray | DataView | NodeJS.ReadableStream, options?: tempy.FileOptions): Promise<string>;
 
 	/**
 	Synchronously write data to a random temp file.
@@ -86,7 +100,7 @@ declare const tempy: {
 	//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/2f3d094aec2cb1b93bb0f4cffce5ebd6'
 	```
 	*/
-	writeSync(fileContent: string | Buffer | TypedArray | DataView, options?: tempy.Options): string;
+	writeSync(fileContent: string | Buffer | TypedArray | DataView, options?: tempy.FileOptions): string;
 
 	/**
 	Get the root temporary directory path.

index.js

@@ -10,7 +10,7 @@ const {promisify} = require('util');
 const pipeline = promisify(stream.pipeline);
 const {writeFile} = fs.promises;
 
-const getPath = () => path.join(tempDir, uniqueString());
+const getPath = (prefix = '') => path.join(tempDir, prefix + uniqueString());
 
 const writeStream = async (filePath, data) => pipeline(data, fs.createWriteStream(filePath));
 
@@ -30,8 +30,8 @@ module.exports.file = options => {
 	return getPath() + (options.extension === undefined || options.extension === null ? '' : '.' + options.extension.replace(/^\./, ''));
 };
 
-module.exports.directory = () => {
-	const directory = getPath();
+module.exports.directory = ({prefix = ''} = {}) => {
+	const directory = getPath(prefix);
 	fs.mkdirSync(directory);
 	return directory;
 };

index.test-d.ts

@@ -1,8 +1,9 @@
 import {expectType, expectError} from 'tsd';
 import tempy = require('.');
 
-const options: tempy.Options = {};
+const options: tempy.FileOptions = {};
 expectType<string>(tempy.directory());
+expectType<string>(tempy.directory({prefix: 'name_'}));
 expectType<string>(tempy.file());
 expectType<string>(tempy.file({extension: 'png'}));
 expectType<string>(tempy.file({name: 'afile.txt'}));

readme.md

@@ -24,6 +24,9 @@ tempy.file({name: 'unicorn.png'});
 
 tempy.directory();
 //=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/2f3d094aec2cb1b93bb0f4cffce5ebd6'
+
+tempy.directory({prefix: 'name'});
+//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T/name_3c085674ad31223b9653c88f725d6b41'
 ```
 
 ## API
@@ -50,10 +53,24 @@ Type: `string`
 
 Filename. Mutually exclusive with the `extension` option.
 
-### tempy.directory()
+### tempy.directory([options])
 
 Get a temporary directory path. The directory is created for you.
 
+#### options
+
+Type: `Object`
+
+##### prefix
+
+_You usually won't need this option. Specify it only when actually needed._
+
+Type: `string`
+
+Directory prefix.
+
+Useful for testing by making it easier to identify cache directories that are created.
+
 ### tempy.write(fileContent, options?)
 
 Write data to a random temp file.

test.js

@@ -33,7 +33,10 @@ test('.file()', t => {
 });
 
 test('.directory()', t => {
+	const prefix = 'name_';
+
 	t.true(tempy.directory().includes(tempDir));
+	t.true(path.basename(tempy.directory({prefix})).startsWith(prefix));
 });
 
 test('.write(string)', async t => {