[docs] walk does not follow or resolve symlinks

Added test to verify behavior

Author: mxcl

Sources/sys/walk.swift

@@ -22,8 +22,7 @@ import libc
  be empty. It is up to you to check `path` is valid before using this
  function.
 
- - Warning: Symbolic links are *resolved*. Don’t expect to get the path of
- the link: you get the path of the file at which it points.
+ - Warning: Symbolic links that point to directories are *not* followed.
 
  - Note: setting recursively to `false` still causes the generator to feed
  you the directory; just not its contents.
@@ -44,8 +43,7 @@ public func walk(paths: String..., recursively: Bool = true) -> RecursibleDirect
  be empty. It is up to you to check `path` is valid before using this
  function.
 
- - Warning: Symbolic links are *resolved*. Don’t expect to get the path of
- the link: you get the path of the file at which it points.
+ - Warning: Symbolic links that point to directories are *not* followed.
 
  - Note: returning `false` from `recursing` still produces that directory
  from the generator; just not its contents.

Tests/sys/PathTests.swift

@@ -126,6 +126,32 @@ class WalkTests: XCTestCase {
 
         XCTAssertEqual(expected.count, 0)
     }
+
+    func testSymlinksNotWalked() {
+        do {
+            try mkdtemp("foo") { root in
+                let root = try realpath(root)
+
+                try mkdir(root, "foo")
+                try mkdir(root, "bar")
+                try mkdir(root, "bar/baz")
+                try mkdir(root, "bar/baz/goo")
+                try symlink(create: "\(root)/foo/symlink", pointingAt: "\(root)/bar", relativeTo: root)
+
+                XCTAssertTrue("\(root)/foo/symlink".isSymlink)
+                XCTAssertEqual(try! realpath("\(root)/foo/symlink"), "\(root)/bar")
+                XCTAssertTrue(try! realpath("\(root)/foo/symlink/baz").isDirectory)
+
+
+                let results = walk(root, "foo").map{$0}
+
+                XCTAssertEqual(results, ["\(root)/foo/symlink"])
+            }
+        } catch {
+            XCTFail("\(error)")
+        }
+    }
+
 }
 
 class StatTests: XCTestCase {