From bc32e2b16786257398c2e8533a18216a177c81c9 Mon Sep 17 00:00:00 2001
From: Chris Sangwin <C.J.Sangwin@ed.ac.uk>
Date: Thu, 16 Jan 2025 09:16:35 +0000
Subject: [PATCH] fix to issue #1359: add Dioptre as extra units.

---
 stack/cas/casstring.units.class.php         |  1 +
 tests/fixtures/answertestfixtures.class.php |  1 +
 tests/input_units_test.php                  | 13 +++++++++++++
 3 files changed, 15 insertions(+)

diff --git a/stack/cas/casstring.units.class.php b/stack/cas/casstring.units.class.php
index 773915e37c..b56516bdb5 100644
--- a/stack/cas/casstring.units.class.php
+++ b/stack/cas/casstring.units.class.php
@@ -156,6 +156,7 @@ class stack_cas_casstring_units {
         ['yd', '36*in', 'yd', 'yard'],
         ['mi', '5280*12*in', 'mi', 'mile'],
         ['lb', '4.4482*N', 'lb', 'pound'],
+        ['dpt', '1/m', 'dpt', 'Dioptre'],
     ];
 
     /**
diff --git a/tests/fixtures/answertestfixtures.class.php b/tests/fixtures/answertestfixtures.class.php
index 55621f4898..696bfb4319 100644
--- a/tests/fixtures/answertestfixtures.class.php
+++ b/tests/fixtures/answertestfixtures.class.php
@@ -2484,6 +2484,7 @@ class stack_answertest_test_data {
         ['Units', '1', '0.0*km/s', '0.0*m/s', 1, 'ATUnits_compatible_units m/s.', ''],
         ['Units', '1', '0.0*m', '0.0*m/s', 0, 'ATUnits_incompatible_units. ATUnits_correct_numerical.', ''],
         ['Units', '1', '0.0', '0.0*m/s', 0, 'ATUnits_SA_no_units.', ''],
+        ['Units', '3', '0.200*dpt', '0.200/m', 1, 'ATUnits_compatible_units 1/m.', ''],
         ['Units', '1', '7*in', '7*in', 1, 'ATUnits_units_match.', 'Imperial'],
         ['Units', '1', '6*in', '0.5*ft', 1, 'ATUnits_compatible_units in.', ''],
         ['Units', '4', '2640*ft', '0.5*mi', 1, 'ATNumSigFigs_WithinRange. ATUnits_compatible_units in.', ''],
diff --git a/tests/input_units_test.php b/tests/input_units_test.php
index 1f5924b12e..48febfc74b 100644
--- a/tests/input_units_test.php
+++ b/tests/input_units_test.php
@@ -1327,4 +1327,17 @@ public function test_validate_student_response_complex_1(): void {
             $state->contentsdisplayed);
         $this->assertEquals('', $state->errors);
     }
+
+    public function test_validate_student_response_dpt(): void {
+        $options = new stack_options();
+        $el = stack_input_factory::make('units', 'sans1', '0.520*dpt');
+        $el->set_parameter('insertStars', 1);
+        $state = $el->validate_student_response(['sans1' => '0.520*dpt'], $options, '0.520*dpt',
+            new stack_cas_security(true));
+        $this->assertEquals(stack_input::VALID, $state->status);
+        $this->assertEquals('', $state->note);
+        $this->assertEquals('0.520*dpt', $state->contentsmodified);
+        $this->assertEquals('\[ 0.520\, \mathrm{dpt} \]', $state->contentsdisplayed);
+        $this->assertEquals('', $state->errors);
+    }
 }