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MDL-68645 output: Make module generators fail if they init the output

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The coding exception hint should say it all. Creating an activity module
should not need any output function call. It turned out it can lead to
hard-to-debug bugs and unexpected behaviour. So better to explicitly
fail and let the developer fix the code.
This commit is contained in:
Tim Hunt 2020-05-09 09:49:38 +01:00 committed by David Mudrák
parent 206e179df5
commit f883c681ff
2 changed files with 27 additions and 1 deletions
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9
lib/pagelib.php
View File

@ -1572,6 +1572,15 @@ class moodle_page {
$this->_wherethemewasinitialised = debug_backtrace();
}
/**
* For diagnostic/debugging purposes, find where the theme setup was triggered.
*
* @return null|array null if theme not yet setup. Stacktrace if it was.
*/
public function get_where_theme_was_initialised() {
return $this->_wherethemewasinitialised;
}
/**
* Reset the theme and output for a new context. This only makes sense from
* external::validate_context(). Do not cheat.

19
lib/testing/generator/module_generator.php
View File

@ -222,11 +222,15 @@ abstract class testing_module_generator extends component_generator_base {
* cmid (corresponding id in course_modules table)
*/
public function create_instance($record = null, array $options = null) {
global $CFG, $DB;
global $CFG, $DB, $PAGE;
require_once($CFG->dirroot.'/course/modlib.php');
$this->instancecount++;
// Creating an activity is a back end operation, which should not cause any output to happen.
// This will allow us to check that the theme was not initialised while creating the module instance.
$outputstartedbefore = $PAGE->get_where_theme_was_initialised();
// Merge options into record and add default values.
$record = $this->prepare_moduleinfo_record($record, $options);
@ -269,6 +273,19 @@ abstract class testing_module_generator extends component_generator_base {
// Prepare object to return with additional field cmid.
$instance = $DB->get_record($this->get_modulename(), array('id' => $moduleinfo->instance), '*', MUST_EXIST);
$instance->cmid = $moduleinfo->coursemodule;
// If the theme was initialised while creating the module instance, something somewhere called an output
// function. Rather than leaving this as a hard-to-debug situation, let's make it fail with a clear error.
$outputstartedafter = $PAGE->get_where_theme_was_initialised();
if ($outputstartedbefore === null && $outputstartedafter !== null) {
throw new coding_exception('Creating a mod_' . $this->get_modulename() . ' activity initialised the theme and output!',
'This should not happen. Creating an activity should be a pure back-end operation. Unnecessarily initialising ' .
'the output mechanism at the wrong time can cause subtle bugs and is a significant performance hit. There is ' .
'likely a call to an output function that caused it:' . PHP_EOL . PHP_EOL .
format_backtrace($outputstartedafter, true));
}
return $instance;
}