From 031f3a1d4b310fe871405b197f02f3cd45d0d32d Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Wed, 27 Nov 2019 20:49:38 +1100
Subject: [PATCH 1/6] MDL-67151 core: format_float can auto detect number of
 decimal points

---
 lib/moodlelib.php            | 12 ++++++++++--
 lib/tests/moodlelib_test.php |  8 ++++++++
 lib/upgrade.txt              |  3 +++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index d10f31d7a97..1b69c4a1281 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -8630,9 +8630,10 @@ function generate_password($maxlen=10) {
  * then it will display '5.4' instead of '5.400' or '5' instead of '5.000'.
  *
  * @param float $float The float to print
- * @param int $decimalpoints The number of decimal places to print.
+ * @param int $decimalpoints The number of decimal places to print. -1 is a special value for auto detect (full precision).
  * @param bool $localized use localized decimal separator
- * @param bool $stripzeros If true, removes final zeros after decimal point
+ * @param bool $stripzeros If true, removes final zeros after decimal point. It will be ignored and the trailing zeros after
+ *                         the decimal point are always striped if $decimalpoints is -1.
  * @return string locale float
  */
 function format_float($float, $decimalpoints=1, $localized=true, $stripzeros=false) {
@@ -8644,6 +8645,13 @@ function format_float($float, $decimalpoints=1, $localized=true, $stripzeros=fal
     } else {
         $separator = '.';
     }
+    if ($decimalpoints == -1) {
+        // The following counts the number of decimals.
+        // It is safe as both floatval() and round() functions have same behaviour when non-numeric values are provided.
+        $floatval = floatval($float);
+        for ($decimalpoints = 0; $floatval != round($float, $decimalpoints); $decimalpoints++);
+    }
+
     $result = number_format($float, $decimalpoints, $separator, '');
     if ($stripzeros) {
         // Remove zeros and final dot if not needed.
diff --git a/lib/tests/moodlelib_test.php b/lib/tests/moodlelib_test.php
index b65af4012b3..82db58e3059 100644
--- a/lib/tests/moodlelib_test.php
+++ b/lib/tests/moodlelib_test.php
@@ -2249,6 +2249,14 @@ class core_moodlelib_testcase extends advanced_testcase {
         // Custom number of decimal places.
         $this->assertEquals('5.43000', format_float(5.43, 5));
 
+        // Auto detect the number of decimal places.
+        $this->assertEquals('5.43', format_float(5.43, -1));
+        $this->assertEquals('5.43', format_float(5.43000, -1));
+        $this->assertEquals('5', format_float(5, -1));
+        $this->assertEquals('5', format_float(5.0, -1));
+        $this->assertEquals('0.543', format_float('5.43e-1', -1));
+        $this->assertEquals('0.543', format_float('5.43000e-1', -1));
+
         // Option to strip ending zeros after rounding.
         $this->assertEquals('5.43', format_float(5.43, 5, true, true));
         $this->assertEquals('5', format_float(5.0001, 3, true, true));
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index b65a321b348..9ea25900d87 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -1,6 +1,9 @@
 This files describes API changes in core libraries and APIs,
 information provided here is intended especially for developers.
 
+=== 3.8.1 ===
+format_float() now accepts a special value (-1) as the $decimalpoints parameter which means auto-detecting number of decimal points.
+
 === 3.8 ===
 * The rotate_image function has been added to the stored_file class (MDL-63349)
 * The yui checknet module is removed. Call \core\session\manager::keepalive instead.

From 481ad40e0e6cf60800524dfa9fb1bc766e74ac72 Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Fri, 22 Nov 2019 16:50:23 +1100
Subject: [PATCH 2/6] MDL-67151 forms: Support for the scientific format in the
 float element

---
 lib/form/float.php | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/form/float.php b/lib/form/float.php
index 8f375c2b986..e1685f207de 100644
--- a/lib/form/float.php
+++ b/lib/form/float.php
@@ -175,12 +175,18 @@ class MoodleQuickForm_float extends MoodleQuickForm_text {
      */
     private function format_float($value) {
         if (is_numeric($value)) {
-            if ($value > 0) {
-                $decimals = strlen($value) - strlen(floor($value)) - 1;
+            // We want to keep trailing zeros after the decimal point if there is any.
+            // Therefore we cannot just call format_float() and pass -1 as the number of decimal points.
+            $pieces = preg_split('/E/i', $value); // In case it is in the scientific format.
+            $decimalpos = strpos($pieces[0], '.');
+            if ($decimalpos !== false) {
+                $decimalpart = substr($pieces[0], $decimalpos + 1);
+                $decimals = strlen($decimalpart);
             } else {
-                $decimals = strlen($value) - strlen(ceil($value)) - 1;
+                $decimals = 0;
             }
-            $value = format_float($value, $decimals);
+            $pieces[0] = format_float($pieces[0], $decimals);
+            $value = implode('E', $pieces);
         }
         return $value;
     }

From bb511f30d607d8ea86bc0d541f8e26b524a86f4d Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Fri, 22 Nov 2019 19:43:09 +1100
Subject: [PATCH 3/6] MDL-67151 core_question: Support scientific format at
 question preview

---
 lib/questionlib.php                           |  2 +-
 question/tests/behat/preview_question.feature | 15 ++++++---------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/lib/questionlib.php b/lib/questionlib.php
index 7aee57fb94e..8566321a1e1 100644
--- a/lib/questionlib.php
+++ b/lib/questionlib.php
@@ -806,7 +806,7 @@ function question_preview_url($questionid, $preferredbehaviour = null,
     }
 
     if (!is_null($maxmark)) {
-        $params['maxmark'] = format_float($maxmark, strlen($maxmark), true, true);
+        $params['maxmark'] = format_float($maxmark, -1);
     }
 
     if (!is_null($displayoptions)) {
diff --git a/question/tests/behat/preview_question.feature b/question/tests/behat/preview_question.feature
index cba500906f5..e3630e34a39 100644
--- a/question/tests/behat/preview_question.feature
+++ b/question/tests/behat/preview_question.feature
@@ -1,4 +1,4 @@
-@core @core_question
+@core @core_question @javascript @_switch_window
 Feature: A teacher can preview questions in the question bank
   In order to ensure the questions are properly created
   As a teacher
@@ -26,7 +26,6 @@ Feature: A teacher can preview questions in the question bank
     When I choose "Preview" action for "Test question to be previewed" in the question bank
     And I switch to "questionpreview" window
 
-  @javascript @_switch_window
   Scenario: Question preview shows the question and other information
     Then the state of "What is pi to two d.p.?" question is shown as "Not yet answered"
     And I should see "Marked out of 1.00"
@@ -34,19 +33,16 @@ Feature: A teacher can preview questions in the question bank
     And I should see "Attempt options"
     And I should see "Display options"
 
-  @javascript @_switch_window
   Scenario: Preview lets the teacher see what happens when an answer is saved
     When I set the field "Answer:" to "1"
     And I press "Save"
     Then the state of "What is pi to two d.p.?" question is shown as "Answer saved"
 
-  @javascript @_switch_window
   Scenario: Preview lets the teacher see what happens when an answer is submitted
     When I set the field "Answer:" to "3.14"
     And I press "Submit and finish"
     Then the state of "What is pi to two d.p.?" question is shown as "Correct"
 
-  @javascript @_switch_window
   Scenario: Preview lets the teacher see what happens with different review options
     Given I set the field "Answer:" to "3.14"
     And I press "Submit and finish"
@@ -56,7 +52,6 @@ Feature: A teacher can preview questions in the question bank
     Then the state of "What is pi to two d.p.?" question is shown as "Complete"
     And I should see "1.00000"
 
-  @javascript @_switch_window
   Scenario: Preview lets the teacher see what happens with different behaviours
     When I set the field "How questions behave" to "Immediate feedback"
     And I set the field "Marked out of" to "3"
@@ -67,18 +62,20 @@ Feature: A teacher can preview questions in the question bank
     And I should see "Mark 0.00 out of 3.00"
     And I should see "Not accurate enough."
 
-  @javascript @_switch_window
   Scenario: Preview lets the teacher "Start again" while previewing
     Given I set the field "Answer:" to "1"
     And I press "Submit and finish"
     When I press "Start again"
     Then the state of "What is pi to two d.p.?" question is shown as "Not yet answered"
 
-  @javascript @_switch_window
   Scenario: Preview lets the teacher "Fill in correct response" while previewing
     When I press "Fill in correct responses"
     Then the field "Answer:" matches value "3.14"
 
-  @javascript @_switch_window
   Scenario: Preview has an option to export the individual quesiton.
     Then following "Download this question in Moodle XML format" should download between "1000" and "2500" bytes
+
+  Scenario: Preview a question with very small grade
+    When I set the field "Marked out of" to "0.00000123456789"
+    And I press "Start again with these options"
+    Then the field "Marked out of" matches value "0.00000123456789"

From fcf199b0ec314a3ec6909e3dee977848c4f4714f Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Fri, 22 Nov 2019 17:50:50 +1100
Subject: [PATCH 4/6] MDL-67151 qtype_numerical: Support for the scientific
 format

---
 .../type/numerical/edit_numerical_form.php    |  2 +-
 .../type/numerical/tests/behat/edit.feature   | 20 ++++++++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/question/type/numerical/edit_numerical_form.php b/question/type/numerical/edit_numerical_form.php
index 6788058255f..c54e06d9563 100644
--- a/question/type/numerical/edit_numerical_form.php
+++ b/question/type/numerical/edit_numerical_form.php
@@ -212,7 +212,7 @@ class qtype_numerical_edit_form extends question_edit_form {
             $question->tolerance[$key] = $answer->tolerance;
 
             if (is_numeric($question->answer[$key])) {
-                $question->answer[$key] = format_float($question->answer[$key], strlen($question->answer[$key]), true, true);
+                $question->answer[$key] = format_float($question->answer[$key], -1);
             }
 
             $key++;
diff --git a/question/type/numerical/tests/behat/edit.feature b/question/type/numerical/tests/behat/edit.feature
index a365876e32d..ea9691983a3 100644
--- a/question/type/numerical/tests/behat/edit.feature
+++ b/question/type/numerical/tests/behat/edit.feature
@@ -20,14 +20,14 @@ Feature: Test editing a Numerical question
     And the following "questions" exist:
       | questioncategory | qtype     | name                  | template |
       | Test questions   | numerical | Numerical for editing | pi |
-    And the following "language customisations" exist:
+
+  Scenario: Edit a Numerical question when using a custom decimal separator
+    Given the following "language customisations" exist:
       | component       | stringid | value |
       | core_langconfig | decsep   | #     |
     And I log in as "teacher1"
     And I am on "Course 1" course homepage
     And I navigate to "Question bank" in current page administration
-
-  Scenario: Edit a Numerical question
     When I choose "Edit question" action for "Numerical for editing" in the question bank
     Then the field "id_answer_0" matches value "3#14"
     When I set the following fields to these values:
@@ -47,3 +47,17 @@ Feature: Test editing a Numerical question
       | id_answer_3    | 3,01     |
     And I press "id_submitbutton"
     Then I should see "Edited Numerical name"
+
+  Scenario: Edit a Numerical question with very small answer
+    Given I log in as "teacher1"
+    And I am on "Course 1" course homepage
+    And I navigate to "Question bank" in current page administration
+    When I choose "Edit question" action for "Numerical for editing" in the question bank
+    And I set the following fields to these values:
+      | id_answer_0    | 0.00000123456789 |
+      | id_tolerance_1 | 0.0000123456789  |
+    And I press "id_submitbutton"
+    And I choose "Edit question" action for "Numerical for editing" in the question bank
+    Then the following fields match these values:
+      | id_answer_0    | 0.00000123456789 |
+      | id_tolerance_1 | 0.0000123456789  |

From 910c2ab7b447447185c7ad67040e1c66cd7d2d2d Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Mon, 25 Nov 2019 15:24:48 +1100
Subject: [PATCH 5/6] MDL-67151 qtype_calculated: Support for the scientific
 format

---
 question/type/calculated/datasetitems_form.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/question/type/calculated/datasetitems_form.php b/question/type/calculated/datasetitems_form.php
index 21ac15f32fa..a29cc7bfe37 100644
--- a/question/type/calculated/datasetitems_form.php
+++ b/question/type/calculated/datasetitems_form.php
@@ -410,7 +410,7 @@ class question_dataset_dependent_items_form extends question_wizard_form {
                     if ($this->_form->getElementType("number[{$j}]") == 'hidden') {
                         // Some of the number elements are from the float type and some are from the hidden type.
                         // We need to manually handle localised floats for hidden elements.
-                        $value = format_float($value, strlen($value), true, true);
+                        $value = format_float($value, -1);
                     }
                     $formdata["number[{$j}]"] = $value;
                     $formdata["definition[{$j}]"] = $defid;
@@ -449,7 +449,7 @@ class question_dataset_dependent_items_form extends question_wizard_form {
                 if ($this->_form->getElementType("number[{$j}]") == 'hidden') {
                     // Some of the number elements are from the float type and some are from the hidden type.
                     // We need to manually handle localised floats for hidden elements.
-                    $value = format_float($value, strlen($value), true, true);
+                    $value = format_float($value, -1);
                 }
                 $formdata["number[{$j}]"] = $value;
                 $formdata["definition[{$j}]"] = $defid;

From 163bff4a184cf2e7a4d6a9b835daec818d7e21d5 Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Mon, 25 Nov 2019 17:07:11 +1100
Subject: [PATCH 6/6] MDL-67151 qtype_calculatedsimple: Support for the
 scientific format

---
 question/type/calculatedsimple/edit_calculatedsimple_form.php | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/question/type/calculatedsimple/edit_calculatedsimple_form.php b/question/type/calculatedsimple/edit_calculatedsimple_form.php
index a48372e02fc..7af36e2d43d 100644
--- a/question/type/calculatedsimple/edit_calculatedsimple_form.php
+++ b/question/type/calculatedsimple/edit_calculatedsimple_form.php
@@ -508,8 +508,7 @@ class qtype_calculatedsimple_edit_form extends qtype_calculated_edit_form {
                             $mform->addElement('hidden', "number[{$j}]", '');
                             $mform->setType("number[{$j}]", PARAM_LOCALISEDFLOAT); // Localisation handling has to be done manually.
                             if (isset($this->formdata["number[{$j}]"])) {
-                                $number = $this->formdata["number[{$j}]"];
-                                $this->formdata["number[{$j}]"] = format_float($number, strlen($number), true, true);
+                                $this->formdata["number[{$j}]"] = format_float($this->formdata["number[{$j}]"], -1);
                             }
                         }