Update dependencies, require Node.js 8

.travis.yml

@@ -2,6 +2,5 @@ language: node_js
 node_js:
   - '10'
   - '8'
-  - '6'
 after_script:
   - 'cat ./coverage/lcov.info | ./node_modules/.bin/coveralls'

package.json

@@ -5,7 +5,7 @@
 	"license": "MIT",
 	"repository": "avajs/find-cache-dir",
 	"engines": {
-		"node": ">=6"
+		"node": ">=8"
 	},
 	"scripts": {
 		"test": "xo && nyc ava"
@@ -23,8 +23,8 @@
 	],
 	"dependencies": {
 		"commondir": "^1.0.1",
-		"make-dir": "^2.0.0",
-		"pkg-dir": "^3.0.0"
+		"make-dir": "^3.0.0",
+		"pkg-dir": "^4.1.0"
 	},
 	"devDependencies": {
 		"ava": "^1.3.1",

readme.md

@@ -60,7 +60,7 @@ findCacheDir({name: 'unicorns'});
 
 ### findCacheDir([options])
 
-Finds the cache directory using the supplied options. The algorithm tries to find a `package.json` file, searching every parent directory of the `cwd` specified (or implied from other options). It returns a `string` containing the absolute path to the cache directory, or `null` if `package.json` was never found.
+Finds the cache directory using the supplied options. The algorithm tries to find a `package.json` file, searching every parent directory of the `cwd` specified (or implied from other options). It returns a `string` containing the absolute path to the cache directory, or `undefined` if `package.json` was never found.
 
 #### options
 

test.js

@@ -35,7 +35,7 @@ test('thunk', t => {
 	t.is(thunk('bar'), path.join(directory, 'bar'));
 });
 
-test('returns null if it can\'t find package.json', t => {
+test('returns undefined if it can\'t find package.json', t => {
 	process.chdir(path.join(__dirname, '..'));
-	t.is(findCacheDir({name: 'foo'}), null);
+	t.is(findCacheDir({name: 'foo'}), undefined);
 });