MDL-75757 phpunit: Add some tolerance to a few failing assertions

Recently, PHPUnit (all versions) did some changes about how the
comparators worked and this has caused some float comparisons
to stop working.

We need to move them to assertEqualsWithDelta(), allowing a small
tolerance to workaround the floats comparison problem.

0.00001 has been decided. And applied to all the similar assertions
within the unittest function, so if more cases are added to them
better be copied with the agreed tolerance.

question/behaviour/deferredcbm/tests/behaviour_type_test.php

@@ -18,6 +18,7 @@
 
 use question_display_options;
 use question_engine;
+use question_testcase;
 
 defined('MOODLE_INTERNAL') || die();
 
@@ -134,8 +135,8 @@ public function test_summarise_usage_max_mark_3() {
     }
 
     public function test_calculate_bonus() {
-        $this->assertEquals(0.05,  $this->behaviourtype->calculate_bonus(1, 1/2));
-        $this->assertEquals(-0.01, $this->behaviourtype->calculate_bonus(2, 9/10));
-        $this->assertEquals(0,     $this->behaviourtype->calculate_bonus(3, 1));
+        $this->assertEqualsWithDelta(0.05,  $this->behaviourtype->calculate_bonus(1, 1 / 2), question_testcase::GRADE_DELTA);
+        $this->assertEqualsWithDelta(-0.01, $this->behaviourtype->calculate_bonus(2, 9 / 10), question_testcase::GRADE_DELTA);
+        $this->assertEqualsWithDelta(0,     $this->behaviourtype->calculate_bonus(3, 1), question_testcase::GRADE_DELTA);
     }
 }

question/engine/tests/helpers.php

@@ -479,6 +479,11 @@ public function build_db_records(array $table) {
 
 abstract class question_testcase extends advanced_testcase {
 
+    /**
+     * Tolerance accepted in some unit tests when float operations are involved.
+     */
+    const GRADE_DELTA = 0.00000005;
+
     public function assert($expectation, $compare, $notused = '') {
 
         if (get_class($expectation) === 'question_pattern_expectation') {

question/type/multianswer/tests/question_test.php

@@ -19,6 +19,7 @@
 use question_attempt_step;
 use question_display_options;
 use question_state;
+use question_testcase;
 
 defined('MOODLE_INTERNAL') || die();
 
@@ -198,7 +199,7 @@ public function test_compute_final_grade() {
                            2 => array('sub1_answer' => 'Owl', 'sub2_answer' => $right),
                           );
         $finalgrade = $question->compute_final_grade($responses, 1);
-        $this->assertEquals(1 / 3 * (1 - 0.2) + 2 / 3 * (1 - 2 * 0.2), $finalgrade);
+        $this->assertEqualsWithDelta(1 / 3 * (1 - 0.2) + 2 / 3 * (1 - 2 * 0.2), $finalgrade, question_testcase::GRADE_DELTA);
 
         // Get subquestion 1 right at 3rd try and subquestion 2 right at 2nd try.
         $responses = array(0 => array('sub1_answer' => 'Dog', 'sub2_answer' => $wrong),
@@ -207,7 +208,7 @@ public function test_compute_final_grade() {
                            3 => array('sub1_answer' => 'Owl', 'sub2_answer' => $right),
                           );
         $finalgrade = $question->compute_final_grade($responses, 1);
-        $this->assertEquals(1 / 3 * (1 - 2 * 0.2) + 2 / 3 * (1 - 0.2), $finalgrade);
+        $this->assertEqualsWithDelta(1 / 3 * (1 - 2 * 0.2) + 2 / 3 * (1 - 0.2), $finalgrade, question_testcase::GRADE_DELTA);
 
         // Get subquestion 1 right at 4th try and subquestion 2 right at 1st try.
         $responses = array(0 => array('sub1_answer' => 'Dog', 'sub2_answer' => $right),
@@ -216,7 +217,7 @@ public function test_compute_final_grade() {
                            3 => array('sub1_answer' => 'Owl', 'sub2_answer' => $right),
                           );
         $finalgrade = $question->compute_final_grade($responses, 1);
-        $this->assertEquals(1 / 3 * (1 - 3 * 0.2) + 2 / 3, $finalgrade);
+        $this->assertEqualsWithDelta(1 / 3 * (1 - 3 * 0.2) + 2 / 3, $finalgrade, question_testcase::GRADE_DELTA);
 
         // Get subquestion 1 right at 4th try and subquestion 2 right 3rd try.
         // Subquestion 2 was right at 1st try, but last change is at 3rd try.
@@ -226,7 +227,7 @@ public function test_compute_final_grade() {
                            3 => array('sub1_answer' => 'Owl', 'sub2_answer' => $right),
                           );
         $finalgrade = $question->compute_final_grade($responses, 1);
-        $this->assertEquals(1 / 3 * (1 - 3 * 0.2) + 2 / 3 * (1 - 2 * 0.2), $finalgrade);
+        $this->assertEqualsWithDelta(1 / 3 * (1 - 3 * 0.2) + 2 / 3 * (1 - 2 * 0.2), $finalgrade, question_testcase::GRADE_DELTA);
 
         // Incomplete responses. Subquestion 1 is right at 4th try and subquestion 2 at 3rd try.
         $responses = array(0 => array('sub1_answer' => 'Dog'),
@@ -235,7 +236,7 @@ public function test_compute_final_grade() {
                            3 => array('sub1_answer' => 'Owl', 'sub2_answer' => $right),
                           );
         $finalgrade = $question->compute_final_grade($responses, 1);
-        $this->assertEquals(1 / 3 * (1 - 3 * 0.2) + 2 / 3 * (1 - 2 * 0.2), $finalgrade);
+        $this->assertEqualsWithDelta(1 / 3 * (1 - 3 * 0.2) + 2 / 3 * (1 - 2 * 0.2), $finalgrade, question_testcase::GRADE_DELTA);
     }
 
     /**