path: assert inputs are strings

This commit makes input type checking consistent across all path
functions.

PR-URL: #5348
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

doc/api/path.markdown

@@ -3,16 +3,16 @@
     Stability: 2 - Stable
 
 This module contains utilities for handling and transforming file
-paths.  Almost all these methods perform only string transformations.
-The file system is not consulted to check whether paths are valid.
+paths. The file system is not consulted to check whether paths are valid.
 
 Use `require('path')` to use this module.  The following methods are provided:
 
-## path.basename(p[, ext])
+## path.basename(path[, ext])
 
-Return the last portion of a path.  Similar to the Unix `basename` command.
+Return the last portion of a path, similar to the Unix `basename` command.
+`path` must be a string. `ext`, if given, must also be a string.
 
-Example:
+Examples:
 
 ```js
 path.basename('/foo/bar/baz/asdf/quux.html')
@@ -46,9 +46,10 @@ process.env.PATH.split(path.delimiter)
 // returns ['C:\\Windows\\system32', 'C:\\Windows', 'C:\\Program Files\\node\\']
 ```
 
-## path.dirname(p)
+## path.dirname(path)
 
-Return the directory name of a path.  Similar to the Unix `dirname` command.
+Return the directory name of a path, similar to the Unix `dirname` command.
+`path` must be a string.
 
 Example:
 
@@ -57,12 +58,14 @@ path.dirname('/foo/bar/baz/asdf/quux')
 // returns '/foo/bar/baz/asdf'
 ```
 
-## path.extname(p)
+## path.extname(path)
 
 Return the extension of the path, from the last '.' to end of string
 in the last portion of the path.  If there is no '.' in the last portion
 of the path or the first character of it is '.', then it returns
-an empty string.  Examples:
+an empty string. `path` must be a string.
+
+Examples:
 
 ```js
 path.extname('index.html')
@@ -100,6 +103,8 @@ string will be the contents of the `base` property.
 If the `base` property is not supplied, a concatenation of the `name` property
 and the `ext` property will be used as the `base` property.
 
+Examples:
+
 ```js
 path.format({
     root : "/",
@@ -123,9 +128,10 @@ path.format({
 ## path.isAbsolute(path)
 
 Determines whether `path` is an absolute path. An absolute path will always
-resolve to the same location, regardless of the working directory.
+resolve to the same location, regardless of the working directory. `path` must
+be a string.
 
-Posix examples:
+Examples on \*nix:
 
 ```js
 path.isAbsolute('/foo/bar') // true
@@ -134,7 +140,7 @@ path.isAbsolute('qux/')     // false
 path.isAbsolute('.')        // false
 ```
 
-Windows examples:
+Examples on Windows:
 
 ```js
 path.isAbsolute('//server')  // true
@@ -151,10 +157,10 @@ path.isAbsolute('.')         // false
 
 Join all arguments together and normalize the resulting path.
 
-Arguments must be strings.  In v0.8, non-string arguments were
+All arguments must be strings.  In v0.8, non-string arguments were
 silently ignored.  In v0.10 and up, an exception is thrown.
 
-Example:
+Examples:
 
 ```js
 path.join('/foo', 'bar', 'baz/asdf', 'quux', '..')
@@ -170,9 +176,10 @@ TypeError: Arguments to path.join must be strings
         zero-length string then `'.'` will be returned, which represents the
         current working directory.
 
-## path.normalize(p)
+## path.normalize(path)
 
-Normalize a string path, taking care of `'..'` and `'.'` parts.
+Normalize a path, taking care of `'..'` and `'.'` parts. `path` must be a
+string.
 
 When multiple slashes are found, they're replaced by a single one;
 when the path contains a trailing slash, it is preserved.
@@ -188,9 +195,9 @@ path.normalize('/foo/bar//baz/asdf/quux/..')
 *Note:* If the path string passed as argument is a zero-length string then `'.'`
         will be returned, which represents the current working directory.
 
-## path.parse(pathString)
+## path.parse(path)
 
-Returns an object from a path string.
+Returns an object from a path. `path` must be a string.
 
 An example on \*nix:
 
@@ -227,7 +234,7 @@ compatible way.
 
 ## path.relative(from, to)
 
-Solve the relative path from `from` to `to`.
+Solve the relative path from `from` to `to`. `from` and `to` must be strings.
 
 At times we have two absolute paths, and we need to derive the relative
 path from one to the other.  This is actually the reverse transform of
@@ -253,13 +260,13 @@ path.relative('/data/orandea/test/aaa', '/data/orandea/impl/bbb')
 
 ## path.resolve([from ...], to)
 
-Resolves `to` to an absolute path.
+Resolves `to` to an absolute path. All arguments must be strings.
 
 If `to` isn't already absolute `from` arguments are prepended in right to left
 order, until an absolute path is found. If after using all `from` paths still
 no absolute path is found, the current working directory is used as well. The
 resulting path is normalized, and trailing slashes are removed unless the path
-gets resolved to the root directory. Non-string `from` arguments are ignored.
+gets resolved to the root directory.
 
 Another way to think of it is as a sequence of `cd` commands in a shell.
 
@@ -320,4 +327,4 @@ An example on Windows:
 Provide access to aforementioned `path` methods but always interact in a win32
 compatible way.
 
-[`path.parse`]: #path_path_parse_pathstring
+[`path.parse`]: #path_path_parse_path

lib/path.js

@@ -734,8 +734,7 @@ const win32 = {
 
 
   dirname: function dirname(path) {
-    if (typeof path !== 'string')
-      path = '' + path;
+    assertPath(path);
     const len = path.length;
     if (len === 0)
       return '.';
@@ -839,8 +838,7 @@ const win32 = {
   basename: function basename(path, ext) {
     if (ext !== undefined && typeof ext !== 'string')
       throw new TypeError('"ext" argument must be a string');
-    if (typeof path !== 'string')
-      path = '' + path;
+    assertPath(path);
     var start = 0;
     var end = -1;
     var matchedSlash = true;
@@ -926,8 +924,7 @@ const win32 = {
 
 
   extname: function extname(path) {
-    if (typeof path !== 'string')
-      path = '' + path;
+    assertPath(path);
     var startDot = -1;
     var startPart = 0;
     var end = -1;
@@ -1364,8 +1361,7 @@ const posix = {
 
 
   dirname: function dirname(path) {
-    if (typeof path !== 'string')
-      path = '' + path;
+    assertPath(path);
     if (path.length === 0)
       return '.';
     var code = path.charCodeAt(0);
@@ -1396,8 +1392,7 @@ const posix = {
   basename: function basename(path, ext) {
     if (ext !== undefined && typeof ext !== 'string')
       throw new TypeError('"ext" argument must be a string');
-    if (typeof path !== 'string')
-      path = '' + path;
+    assertPath(path);
 
     var start = 0;
     var end = -1;
@@ -1471,8 +1466,7 @@ const posix = {
 
 
   extname: function extname(path) {
-    if (typeof path !== 'string')
-      path = '' + path;
+    assertPath(path);
     var startDot = -1;
     var startPart = 0;
     var end = -1;

test/parallel/test-path.js

@@ -23,11 +23,11 @@ assert.equal(path.win32.basename('basename.ext'), 'basename.ext');
 assert.equal(path.win32.basename('basename.ext\\'), 'basename.ext');
 assert.equal(path.win32.basename('basename.ext\\\\'), 'basename.ext');
 assert.equal(path.win32.basename('foo'), 'foo');
-assert.equal(path.win32.basename(null), 'null');
-assert.equal(path.win32.basename(true), 'true');
-assert.equal(path.win32.basename(1), '1');
-assert.equal(path.win32.basename(), 'undefined');
-assert.equal(path.win32.basename({}), '[object Object]');
+assert.throws(path.win32.basename.bind(null, null), TypeError);
+assert.throws(path.win32.basename.bind(null, true), TypeError);
+assert.throws(path.win32.basename.bind(null, 1), TypeError);
+assert.throws(path.win32.basename.bind(null), TypeError);
+assert.throws(path.win32.basename.bind(null, {}), TypeError);
 
 // On unix a backslash is just treated as any other character.
 assert.equal(path.posix.basename('\\dir\\basename.ext'), '\\dir\\basename.ext');
@@ -36,11 +36,11 @@ assert.equal(path.posix.basename('basename.ext'), 'basename.ext');
 assert.equal(path.posix.basename('basename.ext\\'), 'basename.ext\\');
 assert.equal(path.posix.basename('basename.ext\\\\'), 'basename.ext\\\\');
 assert.equal(path.posix.basename('foo'), 'foo');
-assert.equal(path.posix.basename(null), 'null');
-assert.equal(path.posix.basename(true), 'true');
-assert.equal(path.posix.basename(1), '1');
-assert.equal(path.posix.basename(), 'undefined');
-assert.equal(path.posix.basename({}), '[object Object]');
+assert.throws(path.posix.basename.bind(null, null), TypeError);
+assert.throws(path.posix.basename.bind(null, true), TypeError);
+assert.throws(path.posix.basename.bind(null, 1), TypeError);
+assert.throws(path.posix.basename.bind(null), TypeError);
+assert.throws(path.posix.basename.bind(null, {}), TypeError);
 
 // POSIX filenames may include control characters
 // c.f. http://www.dwheeler.com/essays/fixing-unix-linux-filenames.html
@@ -60,11 +60,11 @@ assert.equal(path.posix.dirname(''), '.');
 assert.equal(path.posix.dirname('/'), '/');
 assert.equal(path.posix.dirname('////'), '/');
 assert.equal(path.posix.dirname('foo'), '.');
-assert.equal(path.posix.dirname(null), '.');
-assert.equal(path.posix.dirname(true), '.');
-assert.equal(path.posix.dirname(1), '.');
-assert.equal(path.posix.dirname(), '.');
-assert.equal(path.posix.dirname({}), '.');
+assert.throws(path.posix.dirname.bind(null, null), TypeError);
+assert.throws(path.posix.dirname.bind(null, true), TypeError);
+assert.throws(path.posix.dirname.bind(null, 1), TypeError);
+assert.throws(path.posix.dirname.bind(null), TypeError);
+assert.throws(path.posix.dirname.bind(null, {}), TypeError);
 
 assert.equal(path.win32.dirname('c:\\'), 'c:\\');
 assert.equal(path.win32.dirname('c:\\foo'), 'c:\\');
@@ -100,11 +100,11 @@ assert.equal(path.win32.dirname(''), '.');
 assert.equal(path.win32.dirname('/'), '/');
 assert.equal(path.win32.dirname('////'), '/');
 assert.equal(path.win32.dirname('foo'), '.');
-assert.equal(path.win32.dirname(null), '.');
-assert.equal(path.win32.dirname(true), '.');
-assert.equal(path.win32.dirname(1), '.');
-assert.equal(path.win32.dirname(), '.');
-assert.equal(path.win32.dirname({}), '.');
+assert.throws(path.win32.dirname.bind(null, null), TypeError);
+assert.throws(path.win32.dirname.bind(null, true), TypeError);
+assert.throws(path.win32.dirname.bind(null, 1), TypeError);
+assert.throws(path.win32.dirname.bind(null), TypeError);
+assert.throws(path.win32.dirname.bind(null, {}), TypeError);
 
 
 // path.extname tests
@@ -180,11 +180,11 @@ assert.equal(path.win32.extname('file\\'), '');
 assert.equal(path.win32.extname('file\\\\'), '');
 assert.equal(path.win32.extname('file.\\'), '.');
 assert.equal(path.win32.extname('file.\\\\'), '.');
-assert.equal(path.win32.extname(null), '');
-assert.equal(path.win32.extname(true), '');
-assert.equal(path.win32.extname(1), '');
-assert.equal(path.win32.extname(), '');
-assert.equal(path.win32.extname({}), '');
+assert.throws(path.win32.extname.bind(null, null), TypeError);
+assert.throws(path.win32.extname.bind(null, true), TypeError);
+assert.throws(path.win32.extname.bind(null, 1), TypeError);
+assert.throws(path.win32.extname.bind(null), TypeError);
+assert.throws(path.win32.extname.bind(null, {}), TypeError);
 
 // On *nix, backslash is a valid name component like any other character.
 assert.equal(path.posix.extname('.\\'), '');
@@ -195,11 +195,11 @@ assert.equal(path.posix.extname('file\\'), '');
 assert.equal(path.posix.extname('file\\\\'), '');
 assert.equal(path.posix.extname('file.\\'), '.\\');
 assert.equal(path.posix.extname('file.\\\\'), '.\\\\');
-assert.equal(path.posix.extname(null), '');
-assert.equal(path.posix.extname(true), '');
-assert.equal(path.posix.extname(1), '');
-assert.equal(path.posix.extname(), '');
-assert.equal(path.posix.extname({}), '');
+assert.throws(path.posix.extname.bind(null, null), TypeError);
+assert.throws(path.posix.extname.bind(null, true), TypeError);
+assert.throws(path.posix.extname.bind(null, 1), TypeError);
+assert.throws(path.posix.extname.bind(null), TypeError);
+assert.throws(path.posix.extname.bind(null, {}), TypeError);
 
 
 // path.join tests
@@ -336,35 +336,34 @@ assert.equal(failures.length, 0, failures.join(''));
 
 
 // Test thrown TypeErrors
-var typeErrorTests = [true, false, 7, null, {}, undefined, [], NaN];
+const typeErrorTests = [true, false, 7, null, {}, undefined, [], NaN];
 
 function fail(fn) {
-  var args = Array.prototype.slice.call(arguments, 1);
+  const args = Array.prototype.slice.call(arguments, 1);
 
   assert.throws(function() {
     fn.apply(null, args);
   }, TypeError);
 }
 
 typeErrorTests.forEach(function(test) {
-  fail(path.join, test);
-  fail(path.resolve, test);
-  fail(path.normalize, test);
-  fail(path.isAbsolute, test);
-  fail(path.relative, test, 'foo');
-  fail(path.relative, 'foo', test);
-  fail(path.parse, test);
-
-  // These methods should throw a TypeError, but do not for backwards
-  // compatibility. Uncommenting these lines in the future should be a goal.
-  // fail(path.dirname, test);
-  // fail(path.basename, test);
-  // fail(path.extname, test);
-
-  // undefined is a valid value as the second argument to basename
-  if (test !== undefined) {
-    fail(path.basename, 'foo', test);
-  }
+  [path.posix, path.win32].forEach(function(namespace) {
+    fail(namespace.join, test);
+    fail(namespace.resolve, test);
+    fail(namespace.normalize, test);
+    fail(namespace.isAbsolute, test);
+    fail(namespace.relative, test, 'foo');
+    fail(namespace.relative, 'foo', test);
+    fail(namespace.parse, test);
+    fail(namespace.dirname, test);
+    fail(namespace.basename, test);
+    fail(namespace.extname, test);
+
+    // undefined is a valid value as the second argument to basename
+    if (test !== undefined) {
+      fail(namespace.basename, 'foo', test);
+    }
+  });
 });