Index: wp-testcase/test_http.php
===================================================================
--- wp-testcase/test_http.php	(revision 712)
+++ wp-testcase/test_http.php	(working copy)
@@ -165,4 +165,63 @@
 }
 class WPHTTP_fsockopen extends _WPHTTP {
 	var $transport = 'fsockopen';
+}
+
+
+// non-transport-specific WP_HTTP Tests
+class WPHTTP extends WPTestCase {
+
+	/**
+	 * @dataProvider make_absolute_url_testcases
+	 */
+	function test_make_absolute_url( $relative_url, $absolute_url, $expected ) {
+		if ( ! is_callable( array( 'WP_HTTP', 'make_absolute_url' ) ) ) {
+			$this->markTestSkipped( "This version of WP_HTTP does't support WP_HTTP::make_absolute_url()" );
+			return;
+		}
+	
+		$actual = WP_HTTP::make_absolute_url( $relative_url, $absolute_url );
+		$this->assertEquals( $expected, $actual );
+	}
+
+	function make_absolute_url_testcases() {
+		// 0: The Location header, 1: The current url, 3: The expected url
+		return array(
+			array( 'http://site.com/', 'http://example.com/', 'http://site.com/' ), // Absolute URL provided
+			array( '/location', '', '/location' ), // No current url provided
+			
+			array( '', 'http://example.com', 'http://example.com/' ), // No location provided
+			
+			// Location provided relative to site root
+			array( '/root-relative-link.ext', 'http://example.com/', 'http://example.com/root-relative-link.ext' ),
+			array( '/root-relative-link.ext?with=query', 'http://example.com/index.ext?query', 'http://example.com/root-relative-link.ext?with=query' ),
+			
+			// Location provided relative to current file/directory
+			array( 'relative-file.ext', 'http://example.com/', 'http://example.com/relative-file.ext' ),
+			array( 'relative-file.ext', 'http://example.com/filename', 'http://example.com/relative-file.ext' ),
+			array( 'relative-file.ext', 'http://example.com/directory/', 'http://example.com/directory/relative-file.ext' ),
+			
+			// Location provided relative to current file/directory but in a parent directory
+			array( '../file-in-parent.ext', 'http://example.com', 'http://example.com/file-in-parent.ext' ),
+			array( '../file-in-parent.ext', 'http://example.com/filename', 'http://example.com/file-in-parent.ext' ),
+			array( '../file-in-parent.ext', 'http://example.com/directory/', 'http://example.com/file-in-parent.ext' ),
+			array( '../file-in-parent.ext', 'http://example.com/directory/filename', 'http://example.com/file-in-parent.ext' ),
+
+			// Location provided in muliple levels higher, including impossible to reach (../ below DOCROOT)
+			array( '../../file-in-grand-parent.ext', 'http://example.com', 'http://example.com/file-in-grand-parent.ext' ),
+			array( '../../file-in-grand-parent.ext', 'http://example.com/filename', 'http://example.com/file-in-grand-parent.ext' ),
+			array( '../../file-in-grand-parent.ext', 'http://example.com/directory/', 'http://example.com/file-in-grand-parent.ext' ),
+			array( '../../file-in-grand-parent.ext', 'http://example.com/directory/filename/', 'http://example.com/file-in-grand-parent.ext' ),
+			array( '../../file-in-grand-parent.ext', 'http://example.com/directory1/directory2/filename', 'http://example.com/file-in-grand-parent.ext' ),
+			
+			// Query strings should attach, or replace existing query string.
+			array( '?query=string', 'http://example.com', 'http://example.com/?query=string' ),
+			array( '?query=string', 'http://example.com/file.ext', 'http://example.com/file.ext?query=string' ),
+			array( '?query=string', 'http://example.com/file.ext?existing=query-string', 'http://example.com/file.ext?query=string' ),
+			array( 'otherfile.ext?query=string', 'http://example.com/file.ext?existing=query-string', 'http://example.com/otherfile.ext?query=string' ),
+			
+			// A file with a leading dot
+			array( '.ext', 'http://example.com/', 'http://example.com/.ext' )
+		);
+	}
 }
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