1DBD::Mock(3) User Contributed Perl Documentation DBD::Mock(3)
2
6 DBD::Mock - Mock database driver for testing
7
9 use DBI;
10 # connect to your as normal, using 'Mock' as your driver name
12 my $dbh = DBI->connect( 'DBI:Mock:', '', '' )
13 || die "Cannot create handle: $DBI::errstr\n";
14 # create a statement handle as normal and execute with parameters
16 my $sth = $dbh->prepare( 'SELECT this, that FROM foo WHERE id = ?' );
17 $sth->execute( 15 );
18 # Now query the statement handle as to what has been done with it
20 my $mock_params = $sth->{mock_params};
21 print "Used statement: ", $sth->{mock_statement}, "\n",
22 "Bound parameters: ", join( ', ', @{ $mock_params } ), "\n";
23
25 Testing with databases can be tricky. If you are developing a system
26 married to a single database then you can make some assumptions about
27 your environment and ask the user to provide relevant connection
28 information. But if you need to test a framework that uses DBI,
29 particularly a framework that uses different types of persistence
30 schemes, then it may be more useful to simply verify what the framework
31 is trying to do -- ensure the right SQL is generated and that the
32 correct parameters are bound. "DBD::Mock" makes it easy to just modify
33 your configuration (presumably held outside your code) and just use it
34 instead of "DBD::Foo" (like DBD::Pg or DBD::mysql) in your framework.
35 There is no distinct area where using this module makes sense. (Some
37 people may successfully argue that this is a solution looking for a
38 problem...) Indeed, if you can assume your users have something like
39 DBD::AnyData or DBD::SQLite or if you do not mind creating a dependency
40 on them then it makes far more sense to use these legitimate driver
41 implementations and test your application in the real world -- at least
42 as much of the real world as you can create in your tests...
43 And if your database handle exists as a package variable or something
45 else easily replaced at test-time then it may make more sense to use
46 Test::MockObject to create a fully dynamic handle. There is an
47 excellent article by chromatic about using Test::MockObject in this and
48 other ways, strongly recommended. (See "SEE ALSO" for a link)
49 How does it work?
51 "DBD::Mock" comprises a set of classes used by DBI to implement a
52 database driver. But instead of connecting to a datasource and
53 manipulating data found there it tracks all the calls made to the
54 database handle and any created statement handles. You can then inspect
55 them to ensure what you wanted to happen actually happened. For
56 instance, say you have a configuration file with your database
57 connection information:
58 [DBI]
60 dsn = DBI:Pg:dbname=myapp
61 user = foo
62 password = bar
63 And this file is read in at process startup and the handle stored for
65 other procedures to use:
66 package ObjectDirectory;
68 my ( $DBH );
70 sub run_at_startup {
72 my ( $class, $config ) = @_;
73 $config ||= read_configuration( ... );
74 my $dsn = $config->{DBI}{dsn};
75 my $user = $config->{DBI}{user};
76 my $pass = $config->{DBI}{password};
77 $DBH = DBI->connect( $dsn, $user, $pass ) || die ...;
78 }
79 sub get_database_handle {
81 return $DBH;
82 }
83 A procedure might use it like this (ignoring any error handling for the
85 moment):
86 package My::UserActions;
88 sub fetch_user {
90 my ( $class, $login ) = @_;
91 my $dbh = ObjectDirectory->get_database_handle;
92 my $sql = q{
93 SELECT login_name, first_name, last_name, creation_date, num_logins
94 FROM users
95 WHERE login_name = ?
96 };
97 my $sth = $dbh->prepare( $sql );
98 $sth->execute( $login );
99 my $row = $sth->fetchrow_arrayref;
100 return ( $row ) ? User->new( $row ) : undef;
101 }
102 So for the purposes of our tests we just want to ensure that:
104 1. The right SQL is being executed
106 2. The right parameters are bound
107 Assume whether the SQL actually works or not is irrelevant for this
109 test :-)
110 To do that our test might look like:
112 my $config = ObjectDirectory->read_configuration( ... );
114 $config->{DBI}{dsn} = 'DBI:Mock:';
115 ObjectDirectory->run_at_startup( $config );
116 my $login_name = 'foobar';
118 my $user = My::UserActions->fetch_user( $login_name );
119 # Get the handle from ObjectDirectory;
121 # this is the same handle used in the
122 # 'fetch_user()' procedure above
123 my $dbh = ObjectDirectory->get_database_handle();
124 # Ask the database handle for the history
126 # of all statements executed against it
127 my $history = $dbh->{mock_all_history};
128 # Now query that history record to
130 # see if our expectations match reality
131 is(scalar(@{$history}), 1, 'Correct number of statements executed' ;
132 my $login_st = $history->[0];
134 like($login_st->statement,
135 qr/SELECT login_name.*FROM users WHERE login_name = ?/sm,
136 'Correct statement generated' );
137 my $params = $login_st->bound_params;
139 is(scalar(@{$params}), 1, 'Correct number of parameters bound');
140 is($params->[0], $login_name, 'Correct value for parameter 1' );
141 # Reset the handle for future operations
143 $dbh->{mock_clear_history} = 1;
144 The list of properties and what they return is listed below. But in an
146 overall view:
147 · A database handle contains the history of all statements created
149 against it. Other properties set for the handle (e.g.,
150 'PrintError', 'RaiseError') are left alone and can be queried as
151 normal, but they do not affect anything. (A future feature may
152 track the sequence/history of these assignments but if there is no
153 demand it probably will not get implemented.)
154 · A statement handle contains the statement it was prepared with plus
156 all bound parameters or parameters passed via "execute()". It can
157 also contain predefined results for the statement handle to
158 'fetch', track how many fetches were called and what its current
159 record is.
160 A Word of Warning
162 This may be an incredibly naive implementation of a DBD. But it works
163 for me ...
164
166 Since this is a normal DBI statement handle we need to expose our
167 tracking information as properties (accessed like a hash) rather than
168 methods.
169 Database Driver Properties
171 mock_connect_fail
172 This is a boolean property which when set to true (1) will not
173 allow DBI to connect. This can be used to simulate a DSN error or
174 authentication failure. This can then be set back to false (0) to
175 resume normal DBI operations. Here is an example of how this works:
176 # install the DBD::Mock driver
178 my $drh = DBI->install_driver('Mock');
179 $drh->{mock_connect_fail} = 1;
181 # this connection will fail
183 my $dbh = DBI->connect('dbi:Mock:', '', '') || die "Cannot connect";
184 # this connection will throw an exception
186 my $dbh = DBI->connect('dbi:Mock:', '', '', { RaiseError => 1 });
187 $drh->{mock_connect_fail} = 0;
189 # this will work now ...
191 my $dbh = DBI->connect(...);
192 This feature is conceptually different from the 'mock_can_connect'
194 attribute of the $dbh in that it has a driver-wide scope, where
195 'mock_can_connect' is handle-wide scope. It also only prevents the
196 initial connection, any $dbh handles created prior to setting
197 'mock_connect_fail' to true (1) will still go on working just fine.
198 mock_data_sources
200 This is an ARRAY reference which holds fake data sources which are
201 returned by the Driver and Database Handle's "data_source()"
202 method.
203 mock_add_data_sources
205 This takes a string and adds it to the 'mock_data_sources'
206 attribute.
207 Database Handle Properties
209 mock_all_history
210 Returns an array reference with all history (a.k.a.
211 "DBD::Mock::StatementTrack") objects created against the database
212 handle in the order they were created. Each history object can then
213 report information about the SQL statement used to create it, the
214 bound parameters, etc..
215 mock_all_history_iterator
217 Returns a "DBD::Mock::StatementTrack::Iterator" object which will
218 iterate through the current set of "DBD::Mock::StatementTrack"
219 object in the history. See the DBD::Mock::StatementTrack::Iterator
220 documentation below for more information.
221 mock_clear_history
223 If set to a true value all previous statement history operations
224 will be erased. This includes the history of currently open
225 handles, so if you do something like:
226 my $dbh = get_handle( ... );
228 my $sth = $dbh->prepare( ... );
229 $dbh->{mock_clear_history} = 1;
230 $sth->execute( 'Foo' );
231 You will have no way to learn from the database handle that the
233 statement parameter 'Foo' was bound.
234 This is useful mainly to ensure you can isolate the statement
236 histories from each other. A typical sequence will look like:
237 set handle to framework
239 perform operations
240 analyze mock database handle
241 reset mock database handle history
242 perform more operations
243 analyze mock database handle
244 reset mock database handle history
245 ...
246 mock_can_connect
248 This statement allows you to simulate a downed database connection.
249 This is useful in testing how your application/tests will perform
250 in the face of some kind of catastrophic event such as a network
251 outage or database server failure. It is a simple boolean value
252 which defaults to on, and can be set like this:
253 # turn the database off
255 $dbh->{mock_can_connect} = 0;
256 # turn it back on again
258 $dbh->{mock_can_connect} = 1;
259 The statement handle checks this value as well, so something like
261 this will fail in the expected way:
262 $dbh = DBI->connect( 'DBI:Mock:', '', '' );
264 $dbh->{mock_can_connect} = 0;
265 # blows up!
267 my $sth = eval { $dbh->prepare( 'SELECT foo FROM bar' ) });
268 if ( $@ ) {
269 # Here, $DBI::errstr = 'No connection present'
270 }
271 Turning off the database after a statement prepare will fail on the
273 statement "execute()", which is hopefully what you would expect:
274 $dbh = DBI->connect( 'DBI:Mock:', '', '' );
276 # ok!
278 my $sth = eval { $dbh->prepare( 'SELECT foo FROM bar' ) });
279 $dbh->{mock_can_connect} = 0;
280 # blows up!
282 $sth->execute;
283 Similarly:
285 $dbh = DBI->connect( 'DBI:Mock:', '', '' );
287 # ok!
289 my $sth = eval { $dbh->prepare( 'SELECT foo FROM bar' ) });
290 # ok!
292 $sth->execute;
293 $dbh->{mock_can_connect} = 0;
295 # blows up!
297 my $row = $sth->fetchrow_arrayref;
298 Note: The handle attribute "Active" and the handle method "ping"
300 will behave according to the value of "mock_can_connect". So if
301 "mock_can_connect" were to be set to 0 (or off), then both "Active"
302 and "ping" would return false values (or 0).
303 mock_add_resultset( \@resultset | \%sql_and_resultset )
305 This stocks the database handle with a record set, allowing you to
306 seed data for your application to see if it works properly.. Each
307 recordset is a simple arrayref of arrays with the first arrayref
308 being the fieldnames used. Every time a statement handle is created
309 it asks the database handle if it has any resultsets available and
310 if so uses it.
311 Here is a sample usage, partially from the test suite:
313 my @user_results = (
315 [ 'login', 'first_name', 'last_name' ],
316 [ 'cwinters', 'Chris', 'Winters' ],
317 [ 'bflay', 'Bobby', 'Flay' ],
318 [ 'alincoln', 'Abe', 'Lincoln' ],
319 );
320 my @generic_results = (
321 [ 'foo', 'bar' ],
322 [ 'this_one', 'that_one' ],
323 [ 'this_two', 'that_two' ],
324 );
325 my $dbh = DBI->connect( 'DBI:Mock:', '', '' );
327 $dbh->{mock_add_resultset} = \@user_results; # add first resultset
328 $dbh->{mock_add_resultset} = \@generic_results; # add second resultset
329 my ( $sth );
330 eval {
331 $sth = $dbh->prepare( 'SELECT login, first_name, last_name FROM foo' );
332 $sth->execute();
333 };
334 # this will fetch rows from the first resultset...
336 my $row1 = $sth->fetchrow_arrayref;
337 my $user1 = User->new( login => $row->[0],
338 first => $row->[1],
339 last => $row->[2] );
340 is( $user1->full_name, 'Chris Winters' );
341 my $row2 = $sth->fetchrow_arrayref;
343 my $user2 = User->new( login => $row->[0],
344 first => $row->[1],
345 last => $row->[2] );
346 is( $user2->full_name, 'Bobby Flay' );
347 ...
348 my $sth_generic = $dbh->prepare( 'SELECT foo, bar FROM baz' );
350 $sth_generic->execute;
351 # this will fetch rows from the second resultset...
353 my $row = $sth->fetchrow_arrayref;
354 You can also associate a resultset with a particular SQL statement
356 instead of adding them in the order they will be fetched:
357 $dbh->{mock_add_resultset} = {
359 sql => 'SELECT foo, bar FROM baz',
360 results => [
361 [ 'foo', 'bar' ],
362 [ 'this_one', 'that_one' ],
363 [ 'this_two', 'that_two' ],
364 ],
365 };
366 This will return the given results when the statement 'SELECT foo,
368 bar FROM baz' is prepared. Note that they will be returned every
369 time the statement is prepared, not just the first. It should also
370 be noted that if you want, for some reason, to change the result
371 set bound to a particular SQL statement, all you need to do is add
372 the result set again with the same SQL statement and DBD::Mock will
373 overwrite it.
374 It should also be noted that the "rows" method will return the
376 number of records stocked in the result set. So if your
377 code/application makes use of the "$sth->rows" method for things
378 like UPDATE and DELETE calls you should stock the result set like
379 so:
380 $dbh->{mock_add_resultset} = {
382 sql => 'UPDATE foo SET baz = 1, bar = 2',
383 # this will appear to have updated 3 rows
384 results => [[ 'rows' ], [], [], []],
385 };
386 # or ...
388 $dbh->{mock_add_resultset} = {
390 sql => 'DELETE FROM foo WHERE bar = 2',
391 # this will appear to have deleted 1 row
392 results => [[ 'rows' ], []],
393 };
394 Now I admit this is not the most elegant way to go about this, but
396 it works for me for now, and until I can come up with a better
397 method, or someone sends me a patch ;) it will do for now.
398 If you want a given statement to fail, you will have to use the
400 hashref method and add a 'failure' key. That key can be handed an
401 arrayref with the error number and error string, in that order. It
402 can also be handed a hashref with two keys - errornum and
403 errorstring. If the 'failure' key has no useful value associated
404 with it, the errornum will be '1' and the errorstring will be
405 'Unknown error'.
406 mock_get_info
408 This attribute can be used to set up values for get_info(). It
409 takes a hashref of attribute_name/value pairs. See DBI for more
410 information on the information types and their meaning.
411 mock_session
413 This attribute can be used to set a current DBD::Mock::Session
414 object. For more information on this, see the DBD::Mock::Session
415 docs below. This attribute can also be used to remove the current
416 session from the $dbh simply by setting it to "undef".
417 mock_last_insert_id
419 This attribute is incremented each time an INSERT statement is
420 passed to "prepare" on a per-handle basis. It's starting value can
421 be set with the 'mock_start_insert_id' attribute (see below).
422 $dbh->{mock_start_insert_id} = 10;
424 my $sth = $dbh->prepare('INSERT INTO Foo (foo, bar) VALUES(?, ?)');
426 $sth->execute(1, 2);
428 # $dbh->{mock_last_insert_id} == 10
429 $sth->execute(3, 4);
431 # $dbh->{mock_last_insert_id} == 11
432 For more examples, please refer to the test file
434 t/025_mock_last_insert_id.t.
435 mock_start_insert_id
437 This attribute can be used to set a start value for the
438 'mock_last_insert_id' attribute. It can also be used to effectively
439 reset the 'mock_last_insert_id' attribute as well.
440 This attribute also can be used with an ARRAY ref parameter, it's
442 behavior is slightly different in that instead of incrementing the
443 value for every "prepare" it will only increment for each
444 "execute". This allows it to be used over multiple "execute" calls
445 in a single $sth. It's usage looks like this:
446 $dbh->{mock_start_insert_id} = [ 'Foo', 10 ];
448 $dbh->{mock_start_insert_id} = [ 'Baz', 20 ];
449 my $sth1 = $dbh->prepare('INSERT INTO Foo (foo, bar) VALUES(?, ?)');
451 my $sth2 = $dbh->prepare('INSERT INTO Baz (baz, buz) VALUES(?, ?)');
453 $sth1->execute(1, 2);
455 # $dbh->{mock_last_insert_id} == 10
456 $sth2->execute(3, 4);
458 # $dbh->{mock_last_insert_id} == 20
459 Note that DBD::Mock's matching of table names in 'INSERT'
461 statements is fairly simple, so if your table names are quoted in
462 the insert statement ("INSERT INTO "Foo"") then you need to quote
463 the name for "mock_start_insert_id":
464 $dbh->{mock_start_insert_id} = [ q{"Foo"}, 10 ];
466 mock_add_parser
468 DBI provides some simple parsing capabilities for 'SELECT'
469 statements to ensure that placeholders are bound properly. And
470 typically you may simply want to check after the fact that a
471 statement is syntactically correct, or at least what you expect.
472 But other times you may want to parse the statement as it is
474 prepared rather than after the fact. There is a hook in this mock
475 database driver for you to provide your own parsing routine or
476 object.
477 The syntax is simple:
479 $dbh->{mock_add_parser} = sub {
481 my ( $sql ) = @_;
482 unless ( $sql =~ /some regex/ ) {
483 die "does not contain secret fieldname";
484 }
485 };
486 You can also add more than one for a handle. They will be called in
488 order, and the first one to fail will halt the parsing process:
489 $dbh->{mock_add_parser} = \&parse_update_sql;
491 $dbh->{mock_add-parser} = \&parse_insert_sql;
492 Depending on the 'PrintError' and 'RaiseError' settings in the
494 database handle any parsing errors encountered will issue a "warn"
495 or "die". No matter what the statement handle will be "undef".
496 Instead of providing a subroutine reference you can use an object.
498 The only requirement is that it implements the method "parse()" and
499 takes a SQL statement as the only argument. So you should be able
500 to do something like the following (untested):
501 my $parser = SQL::Parser->new( 'mysql', { RaiseError => 1 } );
503 $dbh->{mock_add_parser} = $parser;
504 mock_data_sources & mock_add_data_sources
506 These properties will dispatch to the Driver's properties of the
507 same name.
508 Database Driver Methods
510 last_insert_id
511 This returns the value of "mock_last_insert_id".
512 In order to capture begin_work(), commit(), and rollback(), DBD::Mock
514 will create statements for them, as if you had issued them in the
515 appropriate SQL command line program. They will go through the standard
516 prepare()-execute() cycle, meaning that any custom SQL parsers will be
517 triggered and DBD::Mock::Session will need to know about these
518 statements.
519 begin_work
521 This will create a statement with SQL of "BEGIN WORK" and no
522 parameters.
523 commit
525 This will create a statement with SQL of "COMMIT" and no
526 parameters.
527 rollback
529 This will create a statement with SQL of "ROLLBACK" and no
530 parameters.
531 Statement Handle Properties
533 Active
534 Returns true if the handle is a 'SELECT' and has more records to
535 fetch, false otherwise. (From the DBI.)
536 mock_statement
538 The SQL statement this statement handle was "prepare"d with. So if
539 the handle were created with:
540 my $sth = $dbh->prepare( 'SELECT * FROM foo' );
542 This would return:
544 SELECT * FROM foo
546 The original statement is unmodified so if you are checking against
548 it in tests you may want to use a regex rather than a straight
549 equality check. (However if you use a phrasebook to store your SQL
550 externally you are a step ahead...)
551 mock_fields
553 Fields used by the statement. As said elsewhere we do no analysis
554 or parsing to find these, you need to define them beforehand. That
555 said, you do not actually need this very often.
556 Note that this returns the same thing as the normal statement
558 property 'FIELD'.
559 mock_params
561 Returns an arrayref of parameters bound to this statement in the
562 order specified by the bind type. For instance, if you created and
563 stocked a handle with:
564 my $sth = $dbh->prepare( 'SELECT * FROM foo WHERE id = ? AND is_active = ?' );
566 $sth->bind_param( 2, 'yes' );
567 $sth->bind_param( 1, 7783 );
568 This would return:
570 [ 7738, 'yes' ]
572 The same result will occur if you pass the parameters via
574 "execute()" instead:
575 my $sth = $dbh->prepare( 'SELECT * FROM foo WHERE id = ? AND is_active = ?' );
577 $sth->execute( 7783, 'yes' );
578 The same using named parameters
580 my $sth = $dbh->prepare( 'SELECT * FROM foo WHERE id = :id AND is_active = :active' );
582 $sth->bind_param( ':id' => 7783 );
583 $sth->bind_param( ':active' => 'yes' );
584 mock_records
586 An arrayref of arrayrefs representing the records the mock
587 statement was stocked with.
588 mock_num_records
590 Number of records the mock statement was stocked with; if never
591 stocked it is still 0. (Some weirdos might expect undef...)
592 mock_num_rows
594 This returns the same value as mock_num_records. And is what is
595 returned by the "rows" method of the statement handle.
596 mock_current_record_num
598 Current record the statement is on; returns 0 in the instances when
599 you have not yet called "execute()" and if you have not yet called
600 a "fetch" method after the execute.
601 mock_is_executed
603 Whether "execute()" has been called against the statement handle.
604 Returns 'yes' if so, 'no' if not.
605 mock_is_finished
607 Whether "finish()" has been called against the statement handle.
608 Returns 'yes' if so, 'no' if not.
609 mock_is_depleted
611 Returns 'yes' if all the records in the recordset have been
612 returned. If no "fetch()" was executed against the statement, or If
613 no return data was set this will return 'no'.
614 mock_my_history
616 Returns a "DBD::Mock::StatementTrack" object which tracks the
617 actions performed by this statement handle. Most of the actions are
618 separately available from the properties listed above, so you
619 should never need this.
620
622 This module can be used to emulate Apache::DBI style DBI connection
623 pooling. Just as with Apache::DBI, you must enable DBD::Mock::Pool
624 before loading DBI.
625 use DBD::Mock qw(Pool);
627 # followed by ...
628 use DBI;
629 While this may not seem to make a lot of sense in a single-process
631 testing scenario, it can be useful when testing code which assumes a
632 multi-process Apache::DBI pooled environment.
633
635 Under the hood this module does most of the work with a
636 "DBD::Mock::StatementTrack" object. This is most useful when you are
637 reviewing multiple statements at a time, otherwise you might want to
638 use the "mock_*" statement handle attributes instead.
639 new( %params )
641 Takes the following parameters:
642 · return_data: Arrayref of return data records
644 · fields: Arrayref of field names
646 · bound_params: Arrayref of bound parameters
648 statement (Statement attribute 'mock_statement')
650 Gets/sets the SQL statement used.
651 fields (Statement attribute 'mock_fields')
653 Gets/sets the fields to use for this statement.
654 bound_params (Statement attribute 'mock_params')
656 Gets/set the bound parameters to use for this statement.
657 return_data (Statement attribute 'mock_records')
659 Gets/sets the data to return when asked (that is, when someone
660 calls 'fetch' on the statement handle).
661 current_record_num (Statement attribute 'mock_current_record_num')
663 Gets/sets the current record number.
664 is_active() (Statement attribute 'Active')
666 Returns true if the statement is a SELECT and has more records to
667 fetch, false otherwise. (This is from the DBI, see the 'Active'
668 docs under 'ATTRIBUTES COMMON TO ALL HANDLES'.)
669 is_executed( $yes_or_no ) (Statement attribute 'mock_is_executed')
671 Sets the state of the tracker 'executed' flag.
672 is_finished( $yes_or_no ) (Statement attribute 'mock_is_finished')
674 If set to 'yes' tells the tracker that the statement is finished.
675 This resets the current record number to '0' and clears out the
676 array ref of returned records.
677 is_depleted() (Statement attribute 'mock_is_depleted')
679 Returns true if the current record number is greater than the
680 number of records set to return.
681 num_fields
683 Returns the number of fields set in the 'fields' parameter.
684 num_rows
686 Returns the number of records in the current result set.
687 num_params
689 Returns the number of parameters set in the 'bound_params'
690 parameter.
691 bound_param( $param_num, $value )
693 Sets bound parameter $param_num to $value. Returns the arrayref of
694 currently-set bound parameters. This corresponds to the
695 'bind_param' statement handle call.
696 bound_param_trailing( @params )
698 Pushes @params onto the list of already-set bound parameters.
699 mark_executed()
701 Tells the tracker that the statement has been executed and resets
702 the current record number to '0'.
703 next_record()
705 If the statement has been depleted (all records returned) returns
706 undef; otherwise it gets the current recordfor returning,
707 increments the current record number and returns the current
708 record.
709 to_string()
711 Tries to give an decent depiction of the object state for use in
712 debugging.
713
715 This object can be used to iterate through the current set of
716 "DBD::Mock::StatementTrack" objects in the history by fetching the
717 'mock_all_history_iterator' attribute from a database handle. This
718 object is very simple and is meant to be a convience to make writing
719 long test script easier. Aside from the constructor ("new") this object
720 has only one method.
721 next
723 Calling "next" will return the next "DBD::Mock::StatementTrack"
725 object in the history. If there are no more
726 "DBD::Mock::StatementTrack" objects available, then this method
727 will return false.
728 reset
730 This will reset the internal pointer to the beginning of the
732 statement history.
733
735 The DBD::Mock::Session object is an alternate means of specifying the
736 SQL statements and result sets for DBD::Mock. The idea is that you can
737 specify a complete 'session' of usage, which will be verified through
738 DBD::Mock. Here is an example:
739 my $session = DBD::Mock::Session->new('my_session' => (
741 {
742 statement => "SELECT foo FROM bar", # as a string
743 results => [[ 'foo' ], [ 'baz' ]]
744 },
745 {
746 statement => qr/UPDATE bar SET foo \= \'bar\'/, # as a reg-exp
747 results => [[]]
748 },
749 {
750 statement => sub { # as a CODE ref
751 my ($SQL, $state) = @_;
752 return $SQL eq "SELECT foo FROM bar";
753 },
754 results => [[ 'foo' ], [ 'bar' ]]
755 },
756 {
757 # with bound parameters
758 statement => "SELECT foo FROM bar WHERE baz = ? AND borg = ?",
759 # check exact bound param value,
760 # then check it against regexp
761 bound_params => [ 10, qr/\d+/ ],
762 results => [[ 'foo' ], [ 'baz' ]]
763 }
764 ));
765 As you can see, a session is essentially made up a list of HASH
767 references we call 'states'. Each state has a 'statement' and a set of
768 'results'. If DBD::Mock finds a session in the 'mock_session'
769 attribute, then it will pass the current $dbh and SQL statement to that
770 DBD::Mock::Session. The SQL statement will be checked against the
771 'statement' field in the current state. If it passes, then the
772 'results' of the current state will get feed to DBD::Mock through the
773 'mock_add_resultset' attribute. We then advance to the next state in
774 the session, and wait for the next call through DBD::Mock. If at any
775 time the SQL statement does not match the current state's 'statement',
776 or the session runs out of available states, an error will be raised
777 (and propagated through the normal DBI error handling based on your
778 values for RaiseError and PrintError).
779 Also, as can be seen in the the session element, bound parameters can
781 also be supplied and tested. In this statement, the SQL is compared,
782 then when the statement is executed, the bound parameters are also
783 checked. The bound parameters much match in both number of parameters
784 and the parameters themselves, or an error will be raised.
785 As can also be seen in the example above, 'statement' fields can come
787 in many forms. The simplest is a string, which will be compared using
788 "eq" against the currently running statement. The next is a reg-exp
789 reference, this too will get compared against the currently running
790 statement. The last option is a CODE ref, this is sort of a catch-all
791 to allow for a wide range of SQL comparison approaches (including using
792 modules like SQL::Statement or SQL::Parser for detailed functional
793 comparisons). The first argument to the CODE ref will be the currently
794 active SQL statement to compare against, the second argument is a
795 reference to the current state HASH (in case you need to alter the
796 results, or store extra information). The CODE is evaluated in boolean
797 context and throws and exception if it is false.
798 new ($session_name, @session_states)
800 A $session_name can be optionally be specified, along with at least
802 one @session_states. If you don't specify a $session_name, then a
803 default one will be created for you. The @session_states must all
804 be HASH references as well, if this conditions fail, an exception
805 will be thrown.
806 verify_statement ($dbh, $SQL)
808 This will check the $SQL against the current state's 'statement'
810 value, and if it passes will add the current state's 'results' to
811 the $dbh. If for some reason the 'statement' value is bad, not of
812 the prescribed type, an exception is thrown. See above for more
813 details.
814 verify_bound_params ($dbh, $params)
816 If the 'bound_params' slot is available in the current state, this
818 will check the $params against the current state's 'bound_params'
819 value. Both number of parameters and the parameters themselves must
820 match, or an error will be raised.
821 reset
823 Calling this method will reset the state of the session object so
825 that it can be reused.
826
828 All functionality listed here is highly experimental and should be used
829 with great caution (if at all).
830 Error handling in mock_add_resultset
832 We have added experimental erro handling in mock_add_resultset the
833 best example is the test file t/023_statement_failure.t, but it
834 looks something like this:
835 $dbh->{mock_add_resultset} = {
837 sql => 'SELECT foo FROM bar',
838 results => DBD::Mock->NULL_RESULTSET,
839 failure => [ 5, 'Ooops!' ],
840 };
841 The 5 is the DBI error number, and 'Ooops!' is the error string
843 passed to DBI. This basically allows you to force an error
844 condition to occur when a given SQL statement is execute. We are
845 currently working on allowing more control on the 'when' and
846 'where' the error happens, look for it in future releases.
847 Attribute Aliasing
849 Basically this feature allows you to alias attributes to other
850 attributes. So for instance, you can alias a commonly expected
851 attribute like 'mysql_insertid' to something DBD::Mock already has
852 like 'mock_last_insert_id'. While you can also just set
853 'mysql_insertid' yourself, this functionality allows it to take
854 advantage of things like the autoincrementing of the
855 'mock_last_insert_id' attribute.
856 Right now this feature is highly experimental, and has been added
858 as a first attempt to automatically handle some of the DBD specific
859 attributes which are commonly used/accessed in DBI programming. The
860 functionality is off by default so as to not cause any issues with
861 backwards compatability, but can easily be turned on and off like
862 this:
863 # turn it on
865 $DBD::Mock::AttributeAliasing++;
866 # turn it off
868 $DBD::Mock::AttributeAliasing = 0;
869 Once this is turned on, you will need to choose a database specific
871 attribute aliasing table like so:
872 DBI->connect('dbi:Mock:MySQL', '', '');
874 The 'MySQL' in the DSN will be picked up and the MySQL specific
876 attribute aliasing will be used.
877 Right now only MySQL is supported by this feature, and even that
879 support is very minimal. Currently the MySQL $dbh and $sth
880 attributes 'mysql_insertid' are aliased to the $dbh attribute
881 'mock_last_insert_id'. It is possible to add more aliases though,
882 using the "DBD::Mock:_set_mock_attribute_aliases" function (see the
883 source code for details).
884
886 Odd $dbh attribute behavior
887 When writing the test suite I encountered some odd behavior with
888 some $dbh attributes. I still need to get deeper into how DBD's
889 work to understand what it is that is actually doing wrong.
890
892 Make DBD specific handlers
893 Each DBD has its own quirks and issues, it would be nice to be able
894 to handle those issues with DBD::Mock in some way. I have an number
895 of ideas already, but little time to sit down and really flesh them
896 out. If you have any suggestions or thoughts, feel free to email me
897 with them.
898 Enhance the DBD::Mock::StatementTrack object
900 I would like to have the DBD::Mock::StatementTrack object handle
901 more of the mock_* attributes. This would encapsulate much of the
902 mock_* behavior in one place, which would be a good thing.
903 I would also like to add the ability to bind a subroutine (or
905 possibly an object) to the result set, so that the results can be
906 somewhat more dynamic and allow for a more realistic interaction.
907
909 DBI
910 DBD::NullP, which provided a good starting point
912 Test::MockObject, which provided the approach
914 Test::MockObject article -
916 <http://www.perl.com/pub/a/2002/07/10/tmo.html>
917 Perl Code Kata: Testing Databases -
919 <http://www.perl.com/pub/a/2005/02/10/database_kata.html>
920
922 We have created a DBD::Mock google group for discussion/questions about
923 this module.
924 <http://groups.google.com/group/DBDMock>
926
928 Thanks to Ryan Gerry for his patch in RT #26604
929 Thanks to Marc Beyer for his patch in RT #16951
930 Thanks to Justin DeVuyst for the mock_connect_fail idea
931 Thanks to Thilo Planz for the code for "bind_param_inout"
932 Thanks to Shlomi Fish for help tracking down RT Bug #11515
933 Thanks to Collin Winter for the patch to fix the "begin_work()",
934 "commit()" and "rollback()" methods.
935 Thanks to Andrew McHarg <amcharg@acm.org> for "fetchall_hashref()",
936 "fetchrow_hashref()" and "selectcol_arrayref()" methods and tests.
937 Thanks to Andrew W. Gibbs for the "mock_last_insert_ids" patch and test
938 Thanks to Chas Owens for patch and test for the "mock_can_prepare",
939 "mock_can_execute", and "mock_can_fetch" features.
940
942 Copyright (C) 2004 Chris Winters <chris@cwinters.com>
943 Copyright (C) 2004-2007 Stevan Little <stevan@iinteractive.com>
945 Copyright (C) 2007 Rob Kinyon <rob.kinyon@gmail.com>
947 Copyright (C) 2011 Mariano Wahlmann <dichoso _at_ gmail.com>
949 This library is free software; you can redistribute it and/or modify it
951 under the same terms as Perl itself.
952
954 Chris Winters <chris@cwinters.com>
955 Stevan Little <stevan@iinteractive.com>
957 Rob Kinyon <rob.kinyon@gmail.com>
959 Mariano Wahlmann <dichoso _at_ gmail.com <gt>
961perl v5.28.1 2019-02-02 DBD::Mock(3)