Prettify test runner a bit:
[lhc/web/wiklou.git] / maintenance / parserTests.inc
index 064370f..7df2c70 100644 (file)
  */
 
 /** */
-$options = array( 'quick', 'color', 'quiet', 'help', 'show-output' );
+$options = array( 'quick', 'color', 'quiet', 'help', 'show-output', 'record' );
 $optionsWithArgs = array( 'regex' );
 
 require_once( 'commandLine.inc' );
-require_once( "$IP/includes/ObjectCache.php" );
-require_once( "$IP/includes/BagOStuff.php" );
-require_once( "$IP/includes/Hooks.php" );
 require_once( "$IP/maintenance/parserTestsParserHook.php" );
 require_once( "$IP/maintenance/parserTestsStaticParserHook.php" );
 require_once( "$IP/maintenance/parserTestsParserTime.php" );
@@ -47,12 +44,6 @@ class ParserTest {
         */
        var $color;
 
-       /**
-        * boolean $lightcolor whereas output should use light colors
-        * @private
-        */
-       var $lightcolor;
-
        /**
         * boolean $showOutput Show test output
         */
@@ -68,7 +59,6 @@ class ParserTest {
                global $options;
 
                # Only colorize output if stdout is a terminal.
-               $this->lightcolor = false;
                $this->color = !wfIsWindows() && posix_isatty(1);
 
                if( isset( $options['color'] ) ) {
@@ -76,18 +66,23 @@ class ParserTest {
                        case 'no':
                                $this->color = false;
                                break;
-                       case 'light':
-                               $this->lightcolor = true;
-                               # Fall through
                        case 'yes':
                        default:
                                $this->color = true;
                                break;
                        }
                }
+               $this->term = $this->color
+                       ? new AnsiTermColorer()
+                       : new DummyTermColorer();
 
                $this->showDiffs = !isset( $options['quick'] );
-               $this->quiet = isset( $options['quiet'] );
+               $this->showProgress = !isset( $options['quiet'] );
+               $this->showFailure = !(
+                       isset( $options['quiet'] )
+                       && ( isset( $options['record'] )
+                               || isset( $options['compare'] ) ) ); // redundant output
+               
                $this->showOutput = isset( $options['show-output'] );
 
 
@@ -97,8 +92,17 @@ class ParserTest {
                        # Matches anything
                        $this->regex = '';
                }
-               
+
+               if( isset( $options['record'] ) ) {
+                       $this->recorder = new DbTestRecorder( $this->term );
+               } elseif( isset( $options['compare'] ) ) {
+                       $this->recorder = new DbTestPreviewer( $this->term );
+               } else {
+                       $this->recorder = new TestRecorder( $this->term );
+               }
+
                $this->hooks = array();
+               $this->functionHooks = array();
        }
 
        /**
@@ -115,38 +119,56 @@ class ParserTest {
        }
 
        /**
-        * Run a series of tests listed in the given text file.
+        * Run a series of tests listed in the given text files.
         * Each test consists of a brief description, wikitext input,
         * and the expected HTML output.
         *
         * Prints status updates on stdout and counts up the total
         * number and percentage of passed tests.
         *
-        * @param string $filename
+        * @param array of strings $filenames
         * @return bool True if passed all tests, false if any tests failed.
         * @public
         */
-       function runTestsFromFile( $filename ) {
+       function runTestsFromFiles( $filenames ) {
+               $this->recorder->start();
+               $ok = true;
+               foreach( $filenames as $filename ) {
+                       $ok = $this->runFile( $filename ) && $ok;
+               }
+               $this->recorder->report();
+               $this->recorder->end();
+               return $ok;
+       }
+
+       private function runFile( $filename ) {
                $infile = fopen( $filename, 'rt' );
                if( !$infile ) {
                        wfDie( "Couldn't open $filename\n" );
+               } else {
+                       global $IP;
+                       $relative = wfRelativePath( $filename, $IP );
+                       print $this->term->color( 1 ) .
+                               "Reading tests from \"$relative\"..." .
+                               $this->term->reset() .
+                               "\n";
                }
 
                $data = array();
                $section = null;
-               $success = 0;
-               $total = 0;
                $n = 0;
+               $ok = true;
                while( false !== ($line = fgets( $infile ) ) ) {
                        $n++;
+                       $matches = array();
                        if( preg_match( '/^!!\s*(\w+)/', $line, $matches ) ) {
                                $section = strtolower( $matches[1] );
                                if( $section == 'endarticle') {
                                        if( !isset( $data['text'] ) ) {
-                                               wfDie( "'endarticle' without 'text' at line $n\n" );
+                                               wfDie( "'endarticle' without 'text' at line $n of $filename\n" );
                                        }
                                        if( !isset( $data['article'] ) ) {
-                                               wfDie( "'endarticle' without 'article' at line $n\n" );
+                                               wfDie( "'endarticle' without 'article' at line $n of $filename\n" );
                                        }
                                        $this->addArticle($this->chomp($data['article']), $this->chomp($data['text']), $n);
                                        $data = array();
@@ -155,7 +177,7 @@ class ParserTest {
                                }
                                if( $section == 'endhooks' ) {
                                        if( !isset( $data['hooks'] ) ) {
-                                               wfDie( "'endhooks' without 'hooks' at line $n\n" );
+                                               wfDie( "'endhooks' without 'hooks' at line $n of $filename\n" );
                                        }
                                        foreach( explode( "\n", $data['hooks'] ) as $line ) {
                                                $line = trim( $line );
@@ -167,15 +189,29 @@ class ParserTest {
                                        $section = null;
                                        continue;
                                }
+                               if( $section == 'endfunctionhooks' ) {
+                                       if( !isset( $data['functionhooks'] ) ) {
+                                               wfDie( "'endfunctionhooks' without 'functionhooks' at line $n of $filename\n" );
+                                       }
+                                       foreach( explode( "\n", $data['functionhooks'] ) as $line ) {
+                                               $line = trim( $line );
+                                               if( $line ) {
+                                                       $this->requireFunctionHook( $line );
+                                               }
+                                       }
+                                       $data = array();
+                                       $section = null;
+                                       continue;
+                               }
                                if( $section == 'end' ) {
                                        if( !isset( $data['test'] ) ) {
-                                               wfDie( "'end' without 'test' at line $n\n" );
+                                               wfDie( "'end' without 'test' at line $n of $filename\n" );
                                        }
                                        if( !isset( $data['input'] ) ) {
-                                               wfDie( "'end' without 'input' at line $n\n" );
+                                               wfDie( "'end' without 'input' at line $n of $filename\n" );
                                        }
                                        if( !isset( $data['result'] ) ) {
-                                               wfDie( "'end' without 'result' at line $n\n" );
+                                               wfDie( "'end' without 'result' at line $n of $filename\n" );
                                        }
                                        if( !isset( $data['options'] ) ) {
                                                $data['options'] = '';
@@ -190,20 +226,19 @@ class ParserTest {
                                                $section = null;
                                                continue;
                                        }
-                                       if( $this->runTest(
+                                       $result = $this->runTest(
                                                $this->chomp( $data['test'] ),
                                                $this->chomp( $data['input'] ),
                                                $this->chomp( $data['result'] ),
-                                               $this->chomp( $data['options'] ) ) ) {
-                                               $success++;
-                                       }
-                                       $total++;
+                                               $this->chomp( $data['options'] ) );
+                                       $ok = $ok && $result;
+                                       $this->recorder->record( $this->chomp( $data['test'] ), $result );
                                        $data = array();
                                        $section = null;
                                        continue;
                                }
                                if ( isset ($data[$section] ) ) {
-                                       wfDie( "duplicate section '$section' at line $n\n" );
+                                       wfDie( "duplicate section '$section' at line $n of $filename\n" );
                                }
                                $data[$section] = '';
                                continue;
@@ -212,19 +247,8 @@ class ParserTest {
                                $data[$section] .= $line;
                        }
                }
-               if( $total > 0 ) {
-                       $ratio = wfPercent( 100 * $success / $total );
-                       print $this->termColor( 1 ) . "\nPassed $success of $total tests ($ratio) ";
-                       if( $success == $total ) {
-                               print $this->termColor( 32 ) . "PASSED!";
-                       } else {
-                               print $this->termColor( 31 ) . "FAILED!";
-                       }
-                       print $this->termReset() . "\n";
-                       return ($success == $total);
-               } else {
-                       wfDie( "No tests found.\n" );
-               }
+               print "\n";
+               return $ok;
        }
 
        /**
@@ -237,7 +261,7 @@ class ParserTest {
         * @return bool
         */
        function runTest( $desc, $input, $result, $opts ) {
-               if( !$this->quiet ) {
+               if( $this->showProgress ) {
                        $this->showTesting( $desc );
                }
 
@@ -251,6 +275,7 @@ class ParserTest {
                        $options->setUseTex(true);
                }
 
+               $m = array();
                if (preg_match('/title=\[\[(.*)\]\]/', $opts, $m)) {
                        $titleText = $m[1];
                }
@@ -264,10 +289,14 @@ class ParserTest {
                foreach( $this->hooks as $tag => $callback ) {
                        $parser->setHook( $tag, $callback );
                }
+               foreach( $this->functionHooks as $tag => $callback ) {
+                       $parser->setFunctionHook( $tag, $callback );
+               }
                wfRunHooks( 'ParserTestParser', array( &$parser ) );
-               
+
                $title =& Title::makeTitle( NS_MAIN, $titleText );
 
+               $matches = array();
                if (preg_match('/\\bpst\\b/i', $opts)) {
                        $out = $parser->preSaveTransform( $input, $title, $user, $options );
                } elseif (preg_match('/\\bmsg\\b/i', $opts)) {
@@ -319,13 +348,21 @@ class ParserTest {
                if( !isset( $this->uploadDir ) ) {
                        $this->uploadDir = $this->setupUploadDir();
                }
-               
+
+               $m = array();
                if( preg_match( '/language=([a-z]+(?:_[a-z]+)?)/', $opts, $m ) ) {
                        $lang = $m[1];
                } else {
                        $lang = 'en';
                }
 
+               if( preg_match( '/variant=([a-z]+(?:-[a-z]+)?)/', $opts, $m ) ) {
+                       $variant = $m[1];
+               } else {
+                       $variant = false;
+               }
+
+
                $settings = array(
                        'wgServer' => 'http://localhost',
                        'wgScript' => '/index.php',
@@ -340,7 +377,7 @@ class ParserTest {
                        'wgLanguageCode' => $lang,
                        'wgContLanguageCode' => $lang,
                        'wgDBprefix' => 'parsertest_',
-
+                       'wgRawHtml' => preg_match('/\\brawhtml\\b/i', $opts),
                        'wgLang' => null,
                        'wgContLang' => null,
                        'wgNamespacesWithSubpages' => array( 0 => preg_match('/\\bsubpage\\b/i', $opts)),
@@ -352,6 +389,8 @@ class ParserTest {
                        'wgLocaltimezone' => 'UTC',
                        'wgAllowExternalImages' => true,
                        'wgUseTidy' => false,
+                       'wgDefaultLanguageVariant' => $variant,
+                       'wgVariantArticlePath' => false,
                        );
                $this->savedGlobals = array();
                foreach( $settings as $var => $val ) {
@@ -373,7 +412,7 @@ class ParserTest {
        # List of temporary tables to create, without prefix
        # Some of these probably aren't necessary
        function listTables() {
-               $tables = array('user', 'page', 'revision', 'text',
+               $tables = array('user', 'page', 'page_restrictions', 'revision', 'text',
                        'pagelinks', 'imagelinks', 'categorylinks',
                        'templatelinks', 'externallinks', 'langlinks',
                        'site_stats', 'hitcounter',
@@ -381,7 +420,8 @@ class ParserTest {
                        'recentchanges',
                        'watchlist', 'math', 'searchindex',
                        'interwiki', 'querycache',
-                       'objectcache', 'job'
+                       'objectcache', 'job', 'redirect',
+                       'querycachetwo'
                );
 
                // FIXME manually adding additional table for the tasks extension
@@ -484,8 +524,9 @@ class ParserTest {
                                'img_media_type'  => MEDIATYPE_BITMAP,
                                'img_major_mime'  => "image",
                                'img_minor_mime'  => "jpeg",
+                               'img_metadata'    => serialize( array() ),
                                ) );
-                               
+
                        # Update certain things in site_stats
                        $db->insert( 'site_stats', array( 'ss_row_id' => 1, 'ss_images' => 1, 'ss_good_articles' => 1 ) );
 
@@ -539,19 +580,54 @@ class ParserTest {
         * @private
         */
        function teardownUploadDir( $dir ) {
-               unlink( "$dir/3/3a/Foobar.jpg" );
-               rmdir( "$dir/3/3a" );
-               rmdir( "$dir/3" );
-               @rmdir( "$dir/thumb/6/65" );
-               @rmdir( "$dir/thumb/6" );
+               // delete the files first, then the dirs.
+               self::deleteFiles(
+                       array (
+                               "$dir/3/3a/Foobar.jpg",
+                               "$dir/thumb/3/3a/Foobar.jpg/180px-Foobar.jpg",
+                               "$dir/thumb/3/3a/Foobar.jpg/200px-Foobar.jpg",
+                               "$dir/thumb/3/3a/Foobar.jpg/640px-Foobar.jpg",
+                               "$dir/thumb/3/3a/Foobar.jpg/120px-Foobar.jpg",
+                       )
+               );
 
-               @unlink( "$dir/thumb/3/3a/Foobar.jpg/180px-Foobar.jpg" );
-               @rmdir( "$dir/thumb/3/3a/Foobar.jpg" );
-               @rmdir( "$dir/thumb/3/3a" );
-               @rmdir( "$dir/thumb/3/39" ); # wtf?
-               @rmdir( "$dir/thumb/3" );
-               @rmdir( "$dir/thumb" );
-               @rmdir( "$dir" );
+               self::deleteDirs(
+                       array (
+                               "$dir/3/3a",
+                               "$dir/3",
+                               "$dir/thumb/6/65",
+                               "$dir/thumb/6",
+                               "$dir/thumb/3/3a/Foobar.jpg",
+                               "$dir/thumb/3/3a",
+                               "$dir/thumb/3",
+                               "$dir/thumb",
+                               "$dir",
+                       )
+               );
+       }
+
+       /**
+        * @desc delete the specified files, if they exist.
+        * @param array $files full paths to files to delete.
+        */
+       private static function deleteFiles( $files ) {
+               foreach( $files as $file ) {
+                       if( file_exists( $file ) ) {
+                               unlink( $file );
+                       }
+               }
+       }
+
+       /**
+        * @desc delete the specified directories, if they exist. Must be empty.
+        * @param array $dirs full paths to directories to delete.
+        */
+       private static function deleteDirs( $dirs ) {
+               foreach( $dirs as $dir ) {
+                       if( is_dir( $dir ) ) {
+                               rmdir( $dir );
+                       }
+               }
        }
 
        /**
@@ -570,8 +646,8 @@ class ParserTest {
         * @private
         */
        function showSuccess( $desc ) {
-               if( !$this->quiet ) {
-                       print $this->termColor( '1;32' ) . 'PASSED' . $this->termReset() . "\n";
+               if( $this->showProgress ) {
+                       print $this->term->color( '1;32' ) . 'PASSED' . $this->term->reset() . "\n";
                }
                return true;
        }
@@ -587,19 +663,21 @@ class ParserTest {
         * @private
         */
        function showFailure( $desc, $result, $html ) {
-               if( $this->quiet ) {
-                       # In quiet mode we didn't show the 'Testing' message before the
-                       # test, in case it succeeded. Show it now:
-                       $this->showTesting( $desc );
-               }
-               print $this->termColor( '1;31' ) . 'FAILED!' . $this->termReset() . "\n";
-               if ( $this->showOutput ) {
-                       print "--- Expected ---\n$result\n--- Actual ---\n$html\n";
-               }
-               if( $this->showDiffs ) {
-                       print $this->quickDiff( $result, $html );
-                       if( !$this->wellFormed( $html ) ) {
-                               print "XML error: $this->mXmlError\n";
+               if( $this->showFailure ) {
+                       if( !$this->showProgress ) {
+                               # In quiet mode we didn't show the 'Testing' message before the
+                               # test, in case it succeeded. Show it now:
+                               $this->showTesting( $desc );
+                       }
+                       print $this->term->color( '31' ) . 'FAILED!' . $this->term->reset() . "\n";
+                       if ( $this->showOutput ) {
+                               print "--- Expected ---\n$result\n--- Actual ---\n$html\n";
+                       }
+                       if( $this->showDiffs ) {
+                               print $this->quickDiff( $result, $html );
+                               if( !$this->wellFormed( $html ) ) {
+                                       print "XML error: $this->mXmlError\n";
+                               }
                        }
                }
                return false;
@@ -645,33 +723,6 @@ class ParserTest {
                fclose( $file );
        }
 
-       /**
-        * Return ANSI terminal escape code for changing text attribs/color,
-        * or empty string if color output is disabled.
-        *
-        * @param string $color Semicolon-separated list of attribute/color codes
-        * @return string
-        * @private
-        */
-       function termColor( $color ) {
-               if($this->lightcolor) {
-                       return $this->color ? "\x1b[1;{$color}m" : '';
-               } else {
-                       return $this->color ? "\x1b[{$color}m" : '';
-               }
-       }
-
-       /**
-        * Return ANSI terminal escape code for restoring default text attributes,
-        * or empty string if color output is disabled.
-        *
-        * @return string
-        * @private
-        */
-       function termReset() {
-               return $this->color ? "\x1b[0m" : '';
-       }
-
        /**
         * Colorize unified diff output if set for ANSI color output.
         * Subtractions are colored blue, additions red.
@@ -683,8 +734,8 @@ class ParserTest {
        function colorDiff( $text ) {
                return preg_replace(
                        array( '/^(-.*)$/m', '/^(\+.*)$/m' ),
-                       array( $this->termColor( 34 ) . '$1' . $this->termReset(),
-                              $this->termColor( 31 ) . '$1' . $this->termReset() ),
+                       array( $this->term->color( 34 ) . '$1' . $this->term->reset(),
+                              $this->term->color( 31 ) . '$1' . $this->term->reset() ),
                        $text );
        }
 
@@ -711,7 +762,7 @@ class ParserTest {
                $art->insertNewArticle($text, '', false, false );
                $this->teardownGlobals();
        }
-       
+
        /**
         * Steal a callback function from the primary parser, save it for
         * application to our scary parser. If the hook is not installed,
@@ -727,6 +778,21 @@ class ParserTest {
                }
        }
 
+       /**
+        * Steal a callback function from the primary parser, save it for
+        * application to our scary parser. If the hook is not installed,
+        * die a painful dead to warn the others.
+        * @param string $name
+        */
+       private function requireFunctionHook( $name ) {
+               global $wgParser;
+               if( isset( $wgParser->mFunctionHooks[$name] ) ) {
+                       $this->functionHooks[$name] = $wgParser->mFunctionHooks[$name];
+               } else {
+                       wfDie( "This test suite requires the '$name' function hook extension.\n" );
+               }
+       }
+
        /*
         * Run the "tidy" command on text if the $wgUseTidy
         * global is true
@@ -772,26 +838,259 @@ class ParserTest {
                $start = max( 0, $position - 10 );
                $before = $position - $start;
                $fragment = '...' .
-                       $this->termColor( 34 ) .
+                       $this->term->color( 34 ) .
                        substr( $text, $start, $before ) .
-                       $this->termColor( 0 ) .
-                       $this->termColor( 31 ) .
-                       $this->termColor( 1 ) .
+                       $this->term->color( 0 ) .
+                       $this->term->color( 31 ) .
+                       $this->term->color( 1 ) .
                        substr( $text, $position, 1 ) .
-                       $this->termColor( 0 ) .
-                       $this->termColor( 34 ) .
+                       $this->term->color( 0 ) .
+                       $this->term->color( 34 ) .
                        substr( $text, $position + 1, 9 ) .
-                       $this->termColor( 0 ) .
+                       $this->term->color( 0 ) .
                        '...';
                $display = str_replace( "\n", ' ', $fragment );
                $caret = '   ' .
                        str_repeat( ' ', $before ) .
-                       $this->termColor( 31 ) .
+                       $this->term->color( 31 ) .
                        '^' .
-                       $this->termColor( 0 );
+                       $this->term->color( 0 );
                return "$display\n$caret";
        }
+}
+
+class AnsiTermColorer {
+       function __construct() {
+       }
+
+       /**
+        * Return ANSI terminal escape code for changing text attribs/color
+        *
+        * @param string $color Semicolon-separated list of attribute/color codes
+        * @return string
+        * @private
+        */
+       function color( $color ) {
+               global $wgCommandLineDarkBg;
+               $light = $wgCommandLineDarkBg ? "1;" : "0;";
+               return "\x1b[{$light}{$color}m";
+       }
+
+       /**
+        * Return ANSI terminal escape code for restoring default text attributes
+        *
+        * @return string
+        * @private
+        */
+       function reset() {
+               return $this->color( 0 );
+       }
+}
+
+/* A colour-less terminal */
+class DummyTermColorer {
+       function color( $color ) {
+               return '';
+       }
+
+       function reset() {
+               return '';
+       }
+}
+
+class TestRecorder {
+       function __construct( $term ) {
+               $this->term = $term;
+       }
+
+       function start() {
+               $this->total = 0;
+               $this->success = 0;
+       }
+
+       function record( $test, $result ) {
+               $this->total++;
+               $this->success += ($result ? 1 : 0);
+       }
+
+       function end() {
+               // dummy
+       }
+
+       function report() {
+               if( $this->total > 0 ) {
+                       $this->reportPercentage( $this->success, $this->total );
+               } else {
+                       wfDie( "No tests found.\n" );
+               }
+       }
+
+       function reportPercentage( $success, $total ) {
+               $ratio = wfPercent( 100 * $success / $total );
+               print $this->term->color( 1 ) . "Passed $success of $total tests ($ratio)... ";
+               if( $success == $total ) {
+                       print $this->term->color( 32 ) . "ALL TESTS PASSED!";
+               } else {
+                       print $this->term->color( 31 ) . "some tests failed!";
+               }
+               print $this->term->reset() . "\n";
+               return ($success == $total);
+       }
+}
+
+class DbTestRecorder extends TestRecorder  {
+       protected $db;      ///< Database connection to the main DB
+       protected $curRun;  ///< run ID number for the current run
+       protected $prevRun; ///< run ID number for the previous run, if any
+
+       function __construct( $term ) {
+               parent::__construct( $term );
+               $this->db = wfGetDB( DB_MASTER );
+       }
+
+       /**
+        * Set up result recording; insert a record for the run with the date
+        * and all that fun stuff
+        */
+       function start() {
+               parent::start();
+
+               $this->db->begin();
+
+               if( ! $this->db->tableExists( 'testrun' ) or ! $this->db->tableExists( 'testitem') ) {
+                       print "WARNING> `testrun` table not found in database. Trying to create table.\n";
+                       dbsource( 'testRunner.sql',  $this->db );
+                       echo "OK, resuming.\n";
+               }
+
+               // We'll make comparisons against the previous run later...
+               $this->prevRun = $this->db->selectField( 'testrun', 'MAX(tr_id)' );
+
+               $this->db->insert( 'testrun',
+                       array(
+                               'tr_date'        => $this->db->timestamp(),
+                               'tr_mw_version'  => SpecialVersion::getVersion(),
+                               'tr_php_version' => phpversion(),
+                               'tr_db_version'  => $this->db->getServerVersion(),
+                               'tr_uname'       => php_uname()
+                       ),
+                       __METHOD__ );
+               $this->curRun = $this->db->insertId();
+       }
+
+       /**
+        * Record an individual test item's success or failure to the db
+        * @param string $test
+        * @param bool $result
+        */
+       function record( $test, $result ) {
+               parent::record( $test, $result );
+               $this->db->insert( 'testitem',
+                       array(
+                               'ti_run'     => $this->curRun,
+                               'ti_name'    => $test,
+                               'ti_success' => $result ? 1 : 0,
+                       ),
+                       __METHOD__ );
+       }
+
+       /**
+        * Commit transaction and clean up for result recording
+        */
+       function end() {
+               $this->db->commit();
+               parent::end();
+       }
+
+       function report() {
+               if( $this->prevRun ) {
+                       $table = array(
+                               array( 'previously failing test(s) now PASSING! :)', 0, 1 ),
+                               array( 'previously PASSING test(s) removed o_O', 1, null ),
+                               array( 'new PASSING test(s) :)', null, 1 ),
+
+                               array( 'previously passing test(s) now FAILING! :(', 1, 0 ),
+                               array( 'previously FAILING test(s) removed O_o', 0, null ),
+                               array( 'new FAILING test(s) :(', null, 0 ),
+                               array( 'still FAILING test(s) :(', 0, 0 ),
+                       );
+                       foreach( $table as $criteria ) {
+                               list( $label, $before, $after ) = $criteria;
+                               $differences = $this->compareResult( $before, $after );
+                               if( $differences ) {
+                                       $count = count($differences);
+                                       printf( "%4d %s\n", $count, $label );
+                                       foreach ($differences as $differing_test_name) {
+                                               print "      * $differing_test_name\n";
+                                       }
+                               }
+                       }
+               } else {
+                       print "No previous test runs to compare against.\n";
+               }
+               print "\n";
+               parent::report();
+       }
+
+       /**
+        ** @desc: Returns an array of the test names with changed results, based on the specified
+        **        before/after criteria.
+        */
+       private function compareResult( $before, $after ) {
+               $testitem = $this->db->tableName( 'testitem' );
+               $prevRun = intval( $this->prevRun );
+               $curRun = intval( $this->curRun );
+               $prevStatus = $this->condition( $before );
+               $curStatus = $this->condition( $after );
+
+               // note: requires mysql >= ver 4.1 for subselects
+               if( is_null( $after ) ) {
+                       $sql = "
+                               select prev.ti_name as t from $testitem as prev
+                                       where prev.ti_run=$prevRun and
+                                               prev.ti_success $prevStatus and
+                                               (select current.ti_success from $testitem as current
+                                                       where current.ti_run=$curRun
+                                                               and prev.ti_name=current.ti_name) $curStatus";
+               } else {
+                       $sql = "
+                               select current.ti_name as t from $testitem as current 
+                                       where current.ti_run=$curRun and
+                                               current.ti_success $curStatus and
+                                               (select prev.ti_success from $testitem as prev
+                                                       where prev.ti_run=$prevRun
+                                                               and prev.ti_name=current.ti_name) $prevStatus";
+               }
+               $result = $this->db->query( $sql, __METHOD__ );
+               $retval = array();
+               while ($row = $this->db->fetchObject( $result )) {
+                       $retval[] = $row->t;
+               }
+               $this->db->freeResult( $result );
+               return $retval;
+       }
 
+       /**
+        ** @desc: Helper function for compareResult() database querying.
+        */
+       private function condition( $value ) {
+               if( is_null( $value ) ) {
+                       return 'IS NULL';
+               } else {
+                       return '=' . intval( $value );
+               }
+       }
+
+}
+
+class DbTestPreviewer extends DbTestRecorder  {
+       /**
+        * Commit transaction and clean up for result recording
+        */
+       function end() {
+               $this->db->rollback();
+               TestRecorder::end();
+       }
 }
 
 ?>