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MySQL Unit Testing Suite
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MyTAP 0.03

MyTAP is a unit testing framework for MySQL 5.x written using fuctions and procedures. It includes a collection of TAP-emitting assertion functions, as well as the ability to integrate with other TAP-emitting test frameworks.


To install MyTAP into a MySQL database, just run mytap.sql:

mysql -u root < mytap.sql

This will install all of the assertion functions, as well as a cache table, into a database named "tap".

MyTAP Test Scripts

Here's an example of how to write a MyTAP test script:

-- Start a transaction.

-- Plan the tests.
SELECT tap.plan(1);

-- Run the tests.
SELECT tap.pass( 'My test passed, w00t!' );

-- Finish the tests and clean up.
CALL tap.finish();

Note how the TAP test functions are reference from another database so as to keep them separate from your application database.

Now you're ready to run your test script!

% mysql -u root --disable-pager --batch --raw --skip-column-names --unbuffered --database test --execute 'source test.sql'
ok 1 - My test passed, w00t!

Yeah, that's rather a lot of options to have to remember to get valid tap. I suggest that you install TAP::Parser::SourceHandler::MyTAP instead and just use its my_prove utility:

% my_prove -u root --database test test.sql

Using MyTAP

The purpose of MyTAP is to provide a wide range of testing utilities that output TAP. TAP, or the "Test Anything Protocol", is an emerging standard for representing the output from unit tests. It owes its success to its format as a simple text-based interface that allows for practical machine parsing and high legibility for humans. TAP started life as part of the test harness for Perl but now has implementations in C/C++, Python, PHP, JavaScript, Perl, PostgreSQL, and now MySQL.

I love it when a plan comes together

Before anything else, you need a testing plan. This basically declares how many tests your script is going to run to protect against premature failure.

The preferred way to do this is to declare a plan by calling the plan() function:

SELECT tap.plan( 42 );

There are rare cases when you will not know beforehand how many tests your script is going to run. In this case, you can declare that you have no plan. (Try to avoid using this as it weakens your test.)

CALL tap.no_plan();

Often, though, you'll be able to calculate the number of tests, like so:

SELECT plan( COUNT(*) )
  FROM foo;

At the end of your script, you should always tell MyTAP that the tests have completed, so that it can output any diagnostics about failures or a discrepancy between the planned number of tests and the number actually run:

CALL tap.finish();

Test names

By convention, each test is assigned a number in order. This is largely done automatically for you. However, it's often very useful to assign a name to each test. Would you rather see this?

  ok 4
  not ok 5
  ok 6

Or this?

  ok 4 - basic multi-variable
  not ok 5 - simple exponential
  ok 6 - force == mass * acceleration

The latter gives you some idea of what failed. It also makes it easier to find the test in your script, simply search for "simple exponential".

Many test functions take a name argument. It's optional, but highly suggested that you use it.

I'm ok, you're not ok

The basic purpose of MyTAP--and of any TAP-emitting test framework, for that matter--is to print out either "ok #" or "not ok #", depending on whether a given test succeeded or failed. Everything else is just gravy.

All of the following functions return "ok" or "not ok" depending on whether the test succeeded or failed.

ok( boolean, description )

SELECT tap.ok( @this = @that, @description );

This function simply evaluates any expression (@this = @that is just a simple example) and uses that to determine if the test succeeded or failed. A true expression passes, a false one fails. Very simple.

For example:

SELECT tap.ok( 9 ^ 2 = 81,    'simple exponential' );
SELECT tap.ok( 9 < 10,        'simple comparison' );
SELECT tap.ok( 'foo' ~ '^f',  'simple regex' );
SELECT tap.ok( active,        concat(name, ' widget active' ))
  FROM widgets;

(Mnemonic: "This is ok.")

The @description is a very short description of the test that will be printed out. It makes it very easy to find a test in your script when it fails and gives others an idea of your intentions. The description is optional, but we very strongly encourage its use.

Should an ok() fail, it will produce some diagnostics:

not ok 18 - sufficient mucus
#     Failed test 18: "sufficient mucus"

Furthermore, should the boolean test result argument be passed as a NULL, ok() will assume a test failure and attach an additional diagnostic:

not ok 18 - sufficient mucus
#     Failed test 18: "sufficient mucus"
#     (test result was NULL)

eq( anyelement, anyelement, description )

isnt_eq( anyelement, anyelement, description )

SELECT tap.eq(   @this, @that, @description );
SELECT tap.not_eq( @this, @that, @description );

Similar to ok(), eq() and not_eq() compare their two arguments with = AND <>, respectively, and use the result of that to determine if the test succeeded or failed. So these:

-- Is the ultimate answer 42?
SELECT tap.eq( ultimate_answer(), 42, 'Meaning of Life' );

-- foo() doesn't return empty
SELECT tap.not_eq( foo(), '', 'Got some foo' );

are similar to these:

SELECT tap.ok(   ultimate_answer() =  42, 'Meaning of Life' );
SELECT tap.isnt( foo()             <> '', 'Got some foo'    );

(Mnemonic: "This is that." "This isn't that.")

Note: NULLs are not treated as unknowns by eq() or not_eq(). That is, if @this and @that are both NULL, the test will pass, and if only one of them is NULL, the test will fail.

So why use these test functions? They produce better diagnostics on failure. ok() cannot know what you are testing for (beyond the description), but eq() and not_eq() know what the test was and why it failed. For example this test:

SELECT tap.eq( 'waffle', 'yarblokos', 'Is foo the same as bar?' );

Will produce something like this:

# Failed test 17:  "Is foo the same as bar?"
#         have: waffle
#         want: yarblokos

So you can figure out what went wrong without re-running the test.

You are encouraged to use eq() and not_eq() over ok() where possible.

matches( anyelement, regex, description )

SELECT matches( @this, '^that', @description );

Similar to eq(), matches() matches @this against the regex /^that/.

So this:

SELECT matches( @this, '^that', 'this is like that' );

is similar to:

SELECT ok( @this REGEXP '^that', 'this is like that' );

(Mnemonic "This matches that".)

Its advantages over ok() are similar to that of eq() and not_eq(): Better diagnostics on failure.

doesnt_match( anyelement, regex, description )

SELECT doesnt_match( @this, '^that', @description );

This functions works exactly as matches() does, only it checks if @this does not match the given pattern.

alike( anyelement, pattern, description )

SELECT alike( @this, 'that%', @description );

Similar to matches(), alike() matches @this against the SQL LIKE pattern 'that%'. So this:

SELECT alike( @this, 'that%', 'this is alike that' );

is similar to:

SELECT ok( @this LIKE 'that%', 'this is like that' );

(Mnemonic "This is like that".)

Its advantages over ok() are similar to that of eq() and not_eq(): Better diagnostics on failure.

unalike( anyelement, pattern, description )

SELECT unalike( @this, 'that%', @description );

Works exactly as alike(), only it checks if @this does not match the given pattern.

pass( description )

fail( description )

SELECT tap.pass( @description );
SELECT @description );

Sometimes you just want to say that the tests have passed. Usually the case is you've got some complicated condition that is difficult to wedge into an ok(). In this case, you can simply use pass() (to declare the test ok) or fail() (for not ok). They are synonyms for ok(1, @description) and ok(0, @description).

Use these functions very, very, very sparingly.

The Schema Things

Need to make sure that your database is designed just the way you think it should be? Use these test functions and rest easy.

A note on comparisons: MyTAP uses a simple equivalence test (=) to compare identifier names.

has_table( database, table, description )

SELECT has_table(DATABASE(), 'sometable', 'I got sometable');

This function tests whether or not a table exists in a database. The first argument is a database name, the second is a table name, and the third is the test description. If you want to test for a table in the current database, use the DATABASE() function to specify the current databasen name. If you omit the test description, it will be set to "Table ':database'.':table' should exist".

No Test for the Wicked

There is more to MyTAP. Oh so much more! You can output your own diagnostics. You can write conditional tests based on the output of utility functions. You can batch up tests in functions. Read on to learn all about it.


If you pick the right test function, you'll usually get a good idea of what went wrong when it failed. But sometimes it doesn't work out that way. So here we have ways for you to write your own diagnostic messages which are safer than just \echo or SELECT foo.

diag( text )

Returns a diagnostic message which is guaranteed not to interfere with test output. Handy for this sort of thing:

-- Output a diagnostic message if the collation is not en_US.UTF-8.
SELECT tap.diag(concat(
     'These tests expect CHARACTER_SET_DATABASE to be en_US.UTF-8,\n',
     'but yours is set to ', VARIABLE_VALUE, '.\n',
     'As a result, some tests may fail. YMMV.'
  FROM information_schema.global_variables
   AND VARIABLE_VALUE <> 'utf-8'

Which would produce:

# These tests expect CHARACTER_SET_DATABASE to be en_US.UTF-8,
# but yours is set to latin1.
# As a result, some tests may fail. YMMV. 

Conditional Tests

Sometimes running a test under certain conditions will cause the test script or function to die. A certain function or feature isn't implemented (such as information_schema.global_variables() prior to MySQL 5.1), some resource isn't available (like a replication), or a third party library isn't available. In these cases it's necessary to skip tests, or declare that they are supposed to fail but will work in the future (a todo test).

skip( how_many, why )

Outputs SKIP test results. Use it in a conditional expression within a SELECT statement to replace the output of a test that you otherwise would have run.

SELECT CASE WHEN mysql_version() < 501000
    THEN skip(1, 'ExtractValue() not supported before 5.1' )
    ELSE ok( ExtractValue('<a><b/></a>', 'count(/a/b)'), 'ExtractValue should work')

SELECT CASE WHEN mysql_version() < 501000
    THEN skip(2, 'ExtractValue() not supported before 5.1' )
    ELSE concat(
        ok( ExtractValue('<a><b/></a>', 'count(/a/b)'), 'ExtractValue should work'),
        ok( ExtractValue('<a><b/></a>', 'count(/a/b)'), 'ExtractValue should work')

Note how use of the conditional CASE statement has been used to determine whether or not to run a couple of tests. If they are to be run, they are run through concat(), so that we can run a few tests in the same query. If we don't want to run them, we call skip() and tell it how many tests we're skipping.

todo( how_many, why )

Declares a series of tests that you expect to fail and why. Perhaps it's because you haven't fixed a bug or haven't finished a new feature:

SELECT todo(2, 'URIGeller not finished');

SET card 'Eight of clubs';
SELECT eq( yourCard(), @card, 'Is THIS your card?' );
SELECT eq( bendSpoon(), 'bent', 'Spoon bending, how original' );

With todo(), @how_many specifies how many tests are expected to fail. pgTAP will run the tests normally, but print out special flags indicating they are "todo" tests. The test harness will interpret these failures as ok. Should any todo test pass, the harness will report it as an unexpected success. You then know that the thing you had todo is done and can remove the call to todo().

The nice part about todo tests, as opposed to simply commenting out a block of tests, is that they're like a programmatic todo list. You know how much work is left to be done, you're aware of what bugs there are, and you'll know immediately when they're fixed.

todo_start( why )

This function allows you declare all subsequent tests as TODO tests, up until the todo_end() function is called.

The todo() syntax is generally pretty good about figuring out whether or not we're in a TODO test. However, often we find it difficult to specify the number of tests that are TODO tests. Thus, you can instead use todo_start() and todo_end() to more easily define the scope of your TODO tests.

Note that you can nest TODO tests, too:

SELECT todo_start('working on this');
-- lots of code
SELECT todo_start('working on that');
-- more code
SELECT todo_end();
SELECT todo_end();

This is generally not recommended, but large testing systems often have weird internal needs.

The todo_start() and todo_end() function should also work with the todo() function, although it's not guaranteed and its use is also discouraged:

SELECT todo_start('working on this');
-- lots of code
SELECT todo(2, 'working on that');
-- Two tests for which the above line applies
-- Followed by more tests scoped till the following line.
SELECT todo_end();

We recommend that you pick one style or another of TODO to be on the safe side.


Stops running tests as TODO tests. This function is fatal if called without a preceding todo_start() method call.


Returns true if the test is currently inside a TODO block.

Utility Functions

Along with the usual array of testing, planning, and diagnostic functions, pTAP provides a few extra functions to make the work of testing more pleasant.


SELECT mytap_version();

Returns the version of MyTAP installed in the server. The value is NUMERIC, and thus suitable for comparing to a decimal value.


SELECT mysql_version();

Returns an integer representation of the server version number. This function is useful for determining whether or not certain tests should be run or skipped (using skip()) depending on the version of MySQL. For example:

SELECT CASE WHEN mysql_version() < 501000
    THEN skip('ExtractValue() not supported before 5.1' )
    ELSE ok( ExtractValue('<a><b/></a>', 'count(/a/b)'), 'ExtractValue should work')

The revision level is in the hundres position, the minor version in the ten thousands position, and the major version in the hundred thousands position and above (assuming MySQL 10 is ever released, it will be in the millions position).

Compose Yourself

So, you've been using MyTAP for a while, and now you want to write your own test functions. Go ahead; I don't mind. In fact, I encourage it. How? Why, by providing a function you can use to test your tests, of course!

But first, a brief primer on writing your own test functions. There isn't much to it, really. Just write your function to do whatever comparison you want. As long as you have a boolean value indicating whether or not the test passed, you're golden. Just then use ok() to ensure that everything is tracked appropriately by a test script.

For example, say that you wanted to create a function to ensure that two text values always compare case-insensitively. Sure you could do this with eq() and the LOWER() function, but if you're doing this all the time, you might want to simplify things. Here's how to go about it:

CREATE FUNCTION lc_is (have TEXT, want TEXT, descr TEXT)
    IF LOWER(have) = LOWER(want) THEN
        RETURN ok(1, descr);
    END IF;
    RETURN concat(ok( 0, descr ), '\n', diag(concat(
           '    Have: ', have,
         '\n    Want: ', want
END //


Yep, that's it. The key is to always use MyTAP's ok() function to guarantee that the output is properly formatted, uses the next number in the sequence, and the results are properly recorded in the database for summarization at the end of the test script. You can also provide diagnostics as appropriate; just append them to the output of ok() as we've done here.

Of course, you don't have to directly use ok(); you can also use another MyTAP function that ultimately calls ok(). IOW, while the above example is instructive, this version is easier on the eyes:

CREATE FUNCTION lc_is ( have TEXT, want TEXT, descr TEXT )
     RETURN eq( LOWER(have), LOWER(want), descr);
END //

But either way, let MyTAP handle recording the test results and formatting the output.

Testing Test Functions

Now you've written your test function. So how do you test it? Why, with this handy-dandy test function!

check_test( test_output, is_ok, name, want_description, want_diag, match_diag )

SELECT check_test(
    lc_eq('This', 'THAT', 'not eq'),
    'lc_eq fail',
    'not eq',
    '    Want: this\n    Have: that'

SELECT check_test(
    lc_eq('This', 'THIS', 'eq'),

This function runs anywhere between one and three tests against a test function. For the impatient, the arguments are:

  • @test_output - The output from your test. Usually it's just returned by a call to the test function itself. Required.
  • @is_ok - Boolean indicating whether or not the test is expected to pass. Required.
  • @name - A brief name for your test, to make it easier to find failures in your test script. Optional.
  • @want_description - Expected test description to be output by the test. Optional. Use an empty string to test that no description is output.
  • @want_diag - Expected diagnostic message output during the execution of a test. Must always follow whatever is output by the call to ok(). Optional. Use an empty string to test that no description is output.
  • @match_diag - Use matches() to compare the diagnostics rather than @eq(). Useful for those situations where you're not sure what will be in the output, but you can match it with a regular expression.

Now, on with the detailed documentation. At its simplest, you just pass in the output of your test function (and it must be one and only one test function's output, or you'll screw up the count, so don't do that!) and a boolean value indicating whether or not you expect the test to have passed. That looks something like the second example above.

All other arguments are optional, but I recommend that you always include a short test name to make it easier to track down failures in your test script. check_test() uses this name to construct descriptions of all of the tests it runs. For example, without a short name, the above example will yield output like so:

not ok 14 - Test should pass

Yeah, but which test? So give it a very succinct name and you'll know what test. If you have a lot of these, it won't be much help. So give each call to check_test() a name:

SELECT check_test(
    lc_eq('This', 'THIS', 'eq'),
    'Simple lc_eq test',

Then you'll get output more like this:

not ok 14 - Simple lc_test should pass

Which will make it much easier to find the failing test in your test script.

The optional fourth argument is the description you expect to be output. This is especially important if your test function generates a description when none is passed to it. You want to make sure that your function generates the test description you think it should! This will cause a second test to be run on your test function. So for something like this:

SELECT check_test(
    lc_eq( ''this'', ''THIS'' ),
    'lc_eq() test',
    'this is THIS'

The output then would look something like this, assuming that the lc_eq() function generated the proper description (the above example does not):

ok 42 - lc_eq() test should pass
ok 43 - lc_eq() test should have the proper description

See how there are two tests run for a single call to check_test()? Be sure to adjust your plan accordingly. Also note how the test name was used in the descriptions for both tests.

If the test had failed, it would output a nice diagnostics. Internally it just uses eq() to compare the strings:

# Failed test 43:  "lc_eq() test should have the proper description"
#         have: 'this is this'
#         want: 'this is THIS'

The fifth argument, @want_diag, which is also optional, compares the diagnostics generated during the test to an expected string. Such diagnostics must follow whatever is output by the call to ok() in your test. Your test function should not call diag() until after it calls ok() or things will get truly funky.

Assuming you've followed that rule in your lc_eq() test function, see what happens when a lc_eq() fails. Write your test to test the diagnostics like so:

SELECT * FROM check_test(
    lc_eq( ''this'', ''THat'' ),
    'lc_eq() failing test',
    'this is THat',
    '    Want: this\n    Have: THat

This of course triggers a third test to run. The output will look like so:

ok 44 - lc_eq() failing test should fail
ok 45 - lc_eq() failing test should have the proper description
ok 46 - lc_eq() failing test should have the proper diagnostics

And of course, it the diagnostic test fails, it will output diagnostics just like a description failure would, something like this:

# Failed test 46:  "lc_eq() failing test should have the proper diagnostics"
#         have:     Have: this
#     Want: that
#         want:     Have: this
#     Want: THat

If you pass in the optional sixth argument, @match_diag, the @want_diag argument will be compared to the actual diagnostic output using matches() instead of eq(). This allows you to use a regular expression in the @want_diag argument to match the output, for those situations where some part of the output might vary, such as time-based diagnostics.

I realize that all of this can be a bit confusing, given the various haves and wants, but it gets the job done. Of course, if your diagnostics use something other than indented "have" and "want", such failures will be easier to read. But either way, do test your diagnostics!

To Do

  • Port lot of other assertion functions from pgTAP.

Public Repository

The source code for MyTAP is available on GitHub. Please feel free to fork and contribute!


David E. Wheeler


  • Michael Schwern and chromatic for Test::More.
  • Adrian Howard for Test::Exception.

Copyright and License

Copyright (c) 2010 David E. Wheeler. Some rights reserved.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies.



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