test || die

Presented by Zoe Slattery at PHP London Conference 2008

As PHP becomes ever more successful the requirement for stability increases and the freedom to make changes in the core code is correspondingly restricted.

Is the test coverage sufficient? Especially given the wide range and depth of change required to implement Unicode support.

Based on experience of contributing PHP tests, I'll talk about tests, coverage and what needs to happen!

Transcript

1. test||die
   Testing the PHP implementation
   Zoë Slattery
   PHP London , February 29th 2008
   

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2. PHP Interpreter
   Extensions ( C )
   PHP code
   Why is the initialisation of
   class values
   unpredictable?
   Enough! – I’m going to
   spend my free time at
   parties…no more PHP
   Another BOGUS bug!
   I want to check­in this
   elegant bug fix but I
   have no clue what else
   it might break…
   Why is ­2^31 a float
   sometimes and an int
   other times?
   WHY?
   

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3. var_dump(PHP_INT_MAX);
   $min = ­PHP_INT_MAX ­ 1;
   var_dump($min);
   $min2 = ­2147483648;
   var_dump($min2);
   ?>
   int(2147483647)
   int(­2147483648)
   float(­2147483648)
   EXAMPLE 1
   

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4. B
   A K
   class C {
   const A = K;
   const B = K;
   }
   class C {
   public static $a = K;
   public static $b = K;
   }
   $b
   $a K
   C::A; K
   B
   A K
   K
   K
   C::$a;
   $b
   $a K
   echo “C::A = “.C::A.”\n”;
   echo “C::B = “.C::B.”\n”;
   6 6
   K
   B
   A K
   K K 6
   echo “C::$a = “.C::$a.”\n”;
   echo “C::$b = “.C::$b.”\n”;
   $b
   $a K
   define(‘K’, 6); K 6
   B
   A K
   define(‘K’, 6); K
   K 6
   $b
   $a K
   Class constants Static variables
   EXAMPLE 2
   

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5. Changes in source/ext, source/Zend, source/tests
   This looks like a lot …but actually – it’s a drop in the ocean ….
   What are we doing?
   2005 2006 2007 2008
   0
   500
   1000
   1500
   2000
   2500
   C and PHPT files changed in PHP 5
   C files added
   C files modified
   PHPT files added
   PHPT files modified
   Year
   Number of files
   

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8. A simple PHPTest
   ­­TEST­­
   strtr() function ­ basic test for strtr()
   ­­FILE­­
   $trans = array("hello"=>"hi",
   "hi"=>"hello",
   "a"=>"A", "world"=>"planet");
   var_dump(strtr("# hi all, I said hello world! #", $trans));
   ?>
   ­­EXPECT­­
   string(32) "# hello All, I sAid hi planet! #"
   

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9. test.phpt
   test.out
   test.exp
   test.diff
   run­tests.php
   Summary
   Summary + files
   Running PHPT tests
   php run­tests.php test.phpt
   Pass
   Fail
   

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10. PHP needs TESTS!
    PHP doesn't have enough test cases
    If you can write PHP you can write tests
    Writing tests can help improve your PHP coding
    Marcus BÖrger's slides on writing tests
    http://talks.somabo.de/
    

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11. Get involved!
    

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12. PHP Worldwide
    http://wiki.pooteeweet.org/TestFest
    LONDON! Second week in May – watch this Wiki!
    

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13. zoe@php.net
    zoe@uk.ibm.com
    The End
    

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14. EXAMPLE 3
    Functions which expect integer input cast floating point values to int.
    #define DVAL_TO_LVAL(d, l) \
    if ((d) > LONG_MAX) { \
    (l) = (unsigned long) (d); \
    } else { \
    (l) = (long) (d); \
    }
    Linux, Windows 32 => lowest 32 bits of the representation as an integer.
    Mac=> lowest 32 bit UNLESS the integer overflows THEN ­1.
    Functions which are passed doubles by mistake will give unpredictable results on all platforms
    unless the function code makes an explicit check.
    

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15. This went into PHP4:
    #define DVAL_TO_LVAL(d, l) \
    if ((d) > LONG_MAX) { \
    (l) = LONG_MAX; \
    } else if ((d) < LONG_MIN) {/
    (l) = LONG_MIN; \
    } else { \
    (l) = (long) (d); \
    }
    Didn't work – Bug 30695
    Will convert 0x80000000 to INT_MAX (0x7FFFFFFF).
    What now?
    special case 0x8000000 to 0xFFFFFFFF (what side effects would there be?)
    every extension does it’s own checking (time consuming!)
    EXAMPLE 3 ­ Fix#1
    

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16. Integer repr'n in
    decimal on Mac
    Integer rep'n in
    decimal on
    Linux/Win
    Integer represented
    in hex on Lin/Win
    Cast to integer
    Floating point
    representation of
    4 bits
    O’flow
    ­1
    1
    0x1
    0001
    0001
    INT_MAX * 2 + 3 (17)
    ­1
    0
    0x0
    0000
    0001
    INT_MAX *2 + 2 (16)
    ­1
    ­1
    0xF
    1111
    INT_MAX *2 + 1 (15)
    ­2
    ­2
    0xE
    1110
    INT_MAX *2 (14)
    ­3
    ­3
    0xD
    1101
    INT_Max * 2 – 1 (13)
    ­7
    ­7
    0x9
    1001
    INT_MAX + 2 (9)
    ­8
    ­8
    0x8
    1000
    INT_MAX + 1 (8)
    7
    7
    0x7
    0111
    INT_MAX (7)
    EXAMPLE 3 ­ details
    

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17. EXAMPLE 3 ­ Fix#2
    # define DVAL_TO_LVAL(d, l) \
    if ((d) > LONG_MAX) { \
    if ((d) >
    MAX_UNSIGNED_INT) { \
    (l) = LONG_MAX;
    \
    } else { \
    (l) = (unsigned
    long) (d); \
    } \
    } else { \
    if((d) < LONG_MIN)
    { \
    (l) = LONG_MIN;
    \
    } else { \
    (l) = (long)
    (d); \
    } \
    }
    

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