address @misterdjules's comments

doc/api/path.markdown

@@ -202,7 +202,7 @@ An example on Windows:
     // returns
     ['C:\Windows\system32', 'C:\Windows', 'C:\Program Files\nodejs\']
 
-## path.parse
+## path.parse(pathString)
 
 Returns an object from a path string.
 
@@ -230,7 +230,7 @@ An example on Windows:
         name : "index"
     }
 
-## path.format
+## path.format(pathObject)
 
 Returns a path string from an object, the opposite of `path.parse` above.
 

lib/path.js

@@ -363,10 +363,19 @@ win32.extname = function(path) {
 };
 
 
-win32.format = function(object) {
-  var root = object.root || '';
-  var dir = object.dir;
-  var base = object.base || '';
+win32.format = function(pathObject) {
+  if (!util.isObject(pathObject)) {
+    throw new TypeError("Parameter 'pathObject' must be an object, not " + typeof pathObject);
+  }
+
+  var root = pathObject.root || '';
+
+  if (!util.isString(root)) {
+    throw new TypeError("'pathObject.root' must be a string or undefined, not " + typeof pathObject.root);
+  }
+
+  var dir = pathObject.dir;
+  var base = pathObject.base || '';
   if (dir.slice(dir.length - 1, dir.length) === win32.sep) {
     return dir + base;
   } else {
@@ -375,8 +384,14 @@ win32.format = function(object) {
 };
 
 
-win32.parse = function(string) {
-  var allParts = win32SplitPath(string);
+win32.parse = function(pathString) {
+  if (!util.isString(pathString)) {
+    throw new TypeError("Parameter 'pathString' must be a string, not " + typeof pathString);
+  }
+  var allParts = win32SplitPath(pathString);
+  if (!allParts || allParts.length !== 4) {
+    throw new TypeError("Invalid path '" + pathString + "'");
+  }
   return {
     root: allParts[0],
     dir: allParts[0] + allParts[1].slice(0, allParts[1].length - 1),
@@ -568,20 +583,39 @@ posix.extname = function(path) {
 };
 
 
-posix.format = function(object) {
-  var root = object.root || '';
+posix.format = function(pathObject) {
+  if (!util.isObject(pathObject)) {
+    throw new TypeError("Parameter 'pathObject' must be an object, not " + typeof pathObject);
+  }
+
+  var root = pathObject.root || '';
+
+  if (!util.isString(root)) {
+    throw new TypeError("'pathObject.root' must be a string or undefined, not " + typeof pathObject.root);
+  }
+
   var sep = posix.sep;
   if (root.indexOf(':') > -1) {
     sep = '\\';
   }
-  var dir = object.dir + sep;
-  var base = object.base || '';
+  var dir = pathObject.dir + sep;
+  var base = pathObject.base || '';
   return dir + base;
 };
 
 
-posix.parse = function(string) {
-  var allParts = posixSplitPath(string);
+posix.parse = function(pathString) {
+  if (!util.isString(pathString)) {
+    throw new TypeError("Parameter 'pathString' must be a string, not " + typeof pathString);
+  }
+  var allParts = posixSplitPath(pathString);
+  if (!allParts || allParts.length !== 4) {
+    throw new TypeError("Invalid path '" + pathString + "'");
+  }
+  allParts[1] = allParts[1] || '';
+  allParts[2] = allParts[2] || '';
+  allParts[3] = allParts[3] || '';
+
   return {
     root: allParts[0],
     dir: allParts[0] + allParts[1].slice(0, allParts[1].length - 1),

test/simple/test-path-parse-format.js

@@ -30,7 +30,8 @@ var winPaths = [
   // unc
   '\\\\server\\share\\file_path',
   '\\\\server two\\shared folder\\file path.zip',
-  '\\\\teela\\admin$\\system32'
+  '\\\\teela\\admin$\\system32',
+  '\\\\?\\UNC\\server\\share'
 
 ];
 
@@ -42,23 +43,50 @@ var unixPaths = [
   'user/dir/another File.zip'
 ];
 
+var errors = [
+  {method: 'parse', input: [null], message: /Parameter 'pathString' must be a string, not/},
+  {method: 'parse', input: [{}], message: /Parameter 'pathString' must be a string, not object/},
+  {method: 'parse', input: [true], message: /Parameter 'pathString' must be a string, not boolean/},
+  {method: 'parse', input: [1], message: /Parameter 'pathString' must be a string, not number/},
+  {method: 'parse', input: [], message: /Parameter 'pathString' must be a string, not undefined/},
+  // {method: 'parse', input: [''], message: /Invalid path/}, // omitted because it's hard to trigger!
+  {method: 'format', input: [null], message: /Parameter 'pathObject' must be an object, not/},
+  {method: 'format', input: [''], message: /Parameter 'pathObject' must be an object, not string/},
+  {method: 'format', input: [true], message: /Parameter 'pathObject' must be an object, not boolean/},
+  {method: 'format', input: [1], message: /Parameter 'pathObject' must be an object, not number/},
+  {method: 'format', input: [{root: true}], message: /'pathObject.root' must be a string or undefined, not boolean/},
+  {method: 'format', input: [{root: 12}], message: /'pathObject.root' must be a string or undefined, not number/},
+];
+
 check(path.win32, winPaths);
 check(path.posix, unixPaths);
+checkErrors(path.win32);
+checkErrors(path.posix);
+
+function checkErrors(path) {
+  errors.forEach(function(errorCase) {
+    try {
+      path[errorCase.method].apply(path, errorCase.input);
+    } catch(err) {
+      assert.ok(err instanceof TypeError);
+      assert.ok(
+        errorCase.message.test(err.message),
+        'expected ' + errorCase.message + ' to match ' + err.message
+      );
+      return;
+    }
+
+    assert.fail('should have thrown');
+  });
+}
+
 
 function check(path, paths) {
   paths.forEach(function(element, index, array) {
-    var count = index + 1;
-    console.log(count + ': `' + element + '`');
     var output = path.parse(element);
-    var keys = Object.keys(output);
-    var values = [];
-    for (var i = 0; i < Object.keys(output).length; i++) {
-      values.push(output[keys[i]]);
-    }
-
     assert.strictEqual(path.format(path.parse(element)), element);
     assert.strictEqual(path.parse(element).dir, path.dirname(element));
     assert.strictEqual(path.parse(element).base, path.basename(element));
     assert.strictEqual(path.parse(element).ext, path.extname(element));
-  })
+  });
 }