diff --git a/filter/mathjaxloader/tests/filtermath_test.php b/filter/mathjaxloader/tests/filtermath_test.php
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+++ b/filter/mathjaxloader/tests/filtermath_test.php
@@ -0,0 +1,102 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+/**
+ * Provides the {@link filter_mathjaxloader_filtermath_testcase} class.
+ *
+ * @package     filter_mathjaxloader
+ * @category    test
+ * @copyright   2018 Markku Riekkinen
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+defined('MOODLE_INTERNAL') || die();
+global $CFG;
+require_once($CFG->dirroot.'/filter/mathjaxloader/filter.php');
+/**
+ * Unit tests for the MathJax loader filter.
+ *
+ * @copyright 2018 Markku Riekkinen
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class filter_mathjaxloader_filtermath_testcase extends advanced_testcase {
+
+    /**
+     * Test the functionality of {@link filter_mathjaxloader::filter()}.
+     *
+     * @param string $inputtext The text given by the user.
+     * @param string $expected The expected output after filtering.
+     *
+     * @dataProvider test_math_filtering_inputs
+     */
+    public function test_math_filtering($inputtext, $expected) {
+        $filter = new filter_mathjaxloader(context_system::instance(), []);
+        $this->assertEquals($expected, $filter->filter($inputtext));
+    }
+
+    /**
+     * Data provider for {@link self::test_math_filtering()}.
+     *
+     * @return array of [inputtext, expectedoutput] tuples.
+     */
+    public function test_math_filtering_inputs() {
+        return [
+            // One inline formula.
+            ['Some inline math \\( y = x^2 \\).',
+            '<span class="filter_mathjaxloader_equation">Some inline math <span class="nolink">\\( y = x^2 \\)</span>.</span>'],
+
+            // One inline and one display.
+            ['Some inline math \\( y = x^2 \\) and display formula \\[ S = \\sum_{n=1}^{\\infty} 2^n \\]',
+            '<span class="filter_mathjaxloader_equation">Some inline math <span class="nolink">\\( y = x^2 \\)</span> and '
+                . 'display formula <span class="nolink">\\[ S = \\sum_{n=1}^{\\infty} 2^n \\]</span></span>'],
+
+            // One display and one inline.
+            ['Display formula \\[ S = \\sum_{n=1}^{\\infty} 2^n \\] and some inline math \\( y = x^2 \\).',
+            '<span class="filter_mathjaxloader_equation">Display formula <span class="nolink">\\[ S = \\sum_{n=1}^{\\infty} 2^n \\]</span> and '
+                . 'some inline math <span class="nolink">\\( y = x^2 \\)</span>.</span>'],
+
+            // One inline and one display (with dollars).
+            ['Some inline math \\( y = x^2 \\) and display formula $$ S = \\sum_{n=1}^{\\infty} 2^n $$',
+            '<span class="filter_mathjaxloader_equation">Some inline math <span class="nolink">\\( y = x^2 \\)</span> and '
+                . 'display formula <span class="nolink">$$ S = \\sum_{n=1}^{\\infty} 2^n $$</span></span>'],
+
+            // One display (with dollars) and one inline.
+            ['Display formula $$ S = \\sum_{n=1}^{\\infty} 2^n $$ and some inline math \\( y = x^2 \\).',
+            '<span class="filter_mathjaxloader_equation">Display formula <span class="nolink">$$ S = \\sum_{n=1}^{\\infty} 2^n $$</span> and '
+                . 'some inline math <span class="nolink">\\( y = x^2 \\)</span>.</span>'],
+
+            // Inline math environment nested inside display environment (using a custom LaTex macro).
+            ['\\[ \\newcommand{\\False}{\\mathsf{F}} \\newcommand{\\NullF}{\\fbox{\\(\\False\\)}} \\] '
+                . 'Text with inline formula using the custom LaTex macro \\( a = \\NullF \\).',
+            '<span class="filter_mathjaxloader_equation"><span class="nolink">'
+                . '\\[ \\newcommand{\\False}{\\mathsf{F}} \\newcommand{\\NullF}{\\fbox{\\(\\False\\)}} \\]</span> '
+                . 'Text with inline formula using the custom LaTex macro <span class="nolink">\\( a = \\NullF \\)</span>.</span>'],
+
+            // Nested environments and some more content.
+            ['\\[ \\newcommand{\\False}{\\mathsf{F}} \\newcommand{\\NullF}{\\fbox{\\(\\False\\)}} \\] '
+                . 'Text with inline formula using the custom LaTex macro \\( a = \\NullF \\). Finally, a display formula '
+                . '$$ b = \\NullF $$',
+            '<span class="filter_mathjaxloader_equation"><span class="nolink">'
+                . '\\[ \\newcommand{\\False}{\\mathsf{F}} \\newcommand{\\NullF}{\\fbox{\\(\\False\\)}} \\]</span> '
+                . 'Text with inline formula using the custom LaTex macro <span class="nolink">\\( a = \\NullF \\)</span>. '
+                . 'Finally, a display formula <span class="nolink">$$ b = \\NullF $$</span></span>'],
+
+            // Broken math: the delimiters ($$) are not closed.
+            ['Writing text and starting display math. $$ k = i^3 \\newcommand{\\False}{\\mathsf{F}} \\newcommand{\\NullF}{\\fbox{\\(\\False\\)}} '
+                . 'More text and inline math \\( x = \\NullF \\).',
+            'Writing text and starting display math. $$ k = i^3 \\newcommand{\\False}{\\mathsf{F}} \\newcommand{\\NullF}{\\fbox{\\(\\False\\)}} '
+                . 'More text and inline math \\( x = \\NullF \\).'],
+        ];
+    }
+}