path: add examples

This change adds several examples, with emphasis on special or edge
cases such as a directory parameter consisting of an empty string.

Change-Id: Ib4ac3d0f6d503493eeed0c4fda7c12acf782e9e2
Reviewed-on: https://go-review.googlesource.com/43010
Reviewed-by: Steve Francia <spf@golang.org>
Run-TryBot: Jaana Burcu Dogan <jbd@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/path/example_test.go

@@ -11,7 +11,12 @@ import (
 
 func ExampleBase() {
 	fmt.Println(path.Base("/a/b"))
-	// Output: b
+	fmt.Println(path.Base("/"))
+	fmt.Println(path.Base(""))
+	// Output:
+	// b
+	// /
+	// .
 }
 
 func ExampleClean() {
@@ -22,6 +27,7 @@ func ExampleClean() {
 		"a/c/b/..",
 		"/../a/c",
 		"/../a/b/../././/c",
+		"",
 	}
 
 	for _, p := range paths {
@@ -35,16 +41,29 @@ func ExampleClean() {
 	// Clean("a/c/b/..") = "a/c"
 	// Clean("/../a/c") = "/a/c"
 	// Clean("/../a/b/../././/c") = "/a/c"
+	// Clean("") = "."
 }
 
 func ExampleDir() {
 	fmt.Println(path.Dir("/a/b/c"))
-	// Output: /a/b
+	fmt.Println(path.Dir("a/b/c"))
+	fmt.Println(path.Dir("/"))
+	fmt.Println(path.Dir(""))
+	// Output:
+	// /a/b
+	// a/b
+	// /
+	// .
 }
 
 func ExampleExt() {
 	fmt.Println(path.Ext("/a/b/c/bar.css"))
-	// Output: .css
+	fmt.Println(path.Ext("/"))
+	fmt.Println(path.Ext(""))
+	// Output:
+	// .css
+	//
+	//
 }
 
 func ExampleIsAbs() {
@@ -56,15 +75,24 @@ func ExampleJoin() {
 	fmt.Println(path.Join("a", "b", "c"))
 	fmt.Println(path.Join("a", "b/c"))
 	fmt.Println(path.Join("a/b", "c"))
-	fmt.Println(path.Join("a/b", "/c"))
+	fmt.Println(path.Join("", ""))
+	fmt.Println(path.Join("a", ""))
+	fmt.Println(path.Join("", "a"))
 	// Output:
 	// a/b/c
 	// a/b/c
 	// a/b/c
-	// a/b/c
+	//
+	// a
+	// a
 }
 
 func ExampleSplit() {
 	fmt.Println(path.Split("static/myfile.css"))
-	// Output: static/ myfile.css
+	fmt.Println(path.Split("myfile.css"))
+	fmt.Println(path.Split(""))
+	// Output:
+	// static/ myfile.css
+	//  myfile.css
+	//
 }