diff --git a/tests/008-save-load-hdf5.phpt b/tests/008-save-load-hdf5.phpt
new file mode 100644
index 0000000..2a4a24e
--- /dev/null
+++ b/tests/008-save-load-hdf5.phpt
@@ -0,0 +1,49 @@
+--TEST--
+Test save/load with HDF5 format for `Arma\Mat`.
+--SKIPIF--
+<?php
+require_once 'includes/loaded.php';
+if (is_php_arma_loaded()) {
+    supports_hdf5();
+}
+?>
+--ENV--
+TMP_FILE=/tmp/php_arma_test.tmp
+--FILE--
+<?php
+
+require_once 'includes/assert.php';
+
+$file_name = getenv('TMP_FILE');
+
+$hdf5_options = [
+    'file_name' => $file_name,
+    'dataset_name' => 'tmp_dataset',
+    'options' => Arma\HDF5Opts::TRANS
+];
+
+$mat = Arma\IMat::init(3, 3, Arma\Fill::RANDN);
+batch_assert('saving with HDF5 format',
+    [true, $mat->save($hdf5_options, Arma\FileType::HDF5_BINARY)]
+);
+
+$mat1 = Arma\IMat::init();
+batch_assert('loading with HDF5 format',
+    [true, $mat1->load($hdf5_options, Arma\FileType::HDF5_BINARY)]
+);
+
+$eq_mat = $mat->equals($mat1);
+batch_assert('loading with HDF5 format',
+    [1, $eq_mat->min()],
+    [1, $eq_mat->max()]
+);
+
+?>
+--CLEAN--
+<?php
+$file_name = getenv('TMP_FILE');
+if (file_exists($file_name)) {
+    unlink($file_name);
+}
+?>
+--EXPECT--
diff --git a/tests/009-comparison-operators.phpt b/tests/009-comparison-operators.phpt
new file mode 100644
index 0000000..ed0fa30
--- /dev/null
+++ b/tests/009-comparison-operators.phpt
@@ -0,0 +1,34 @@
+--TEST--
+Test operator overloading for comparisons.
+--SKIPIF--
+<?php
+require_once 'includes/loaded.php';
+require_once 'includes/supports.php';
+if (is_php_arma_loaded()) {
+    supports_operator_overloading();
+}
+?>
+--FILE--
+<?php
+
+require_once 'includes/assert.php';
+
+$mat0 = Arma\DMat::init(3, 3, Arma\Fill::RANDU);
+$mat1 = Arma\DMat::init(3, 3, Arma\Fill::RANDU);
+
+$comp = function ($expected, $got) {
+    $compare_result = $expected->equals($got);
+    return $compare_result->max() == 1 && $compare_result->min() == 1;
+};
+
+batch_assert_ex('operator overloading for comparisons', $comp,
+    [$mat0->equals($mat1),         $mat0 == $mat1],
+    [$mat0->notEquals($mat1),      $mat0 != $mat1],
+    [$mat0->smallerThan($mat1),    $mat0 <  $mat1],
+    [$mat0->greaterThan($mat1),    $mat0 >  $mat1],
+    [$mat0->notSmallerThan($mat1), $mat0 >= $mat1],
+    [$mat0->notGreaterThan($mat1), $mat0 <= $mat1]
+);
+
+?>
+--EXPECT--
diff --git a/tests/includes/assert.php b/tests/includes/assert.php
index 9300a4b..888892f 100644
--- a/tests/includes/assert.php
+++ b/tests/includes/assert.php
@@ -1,16 +1,19 @@
 <?php
 
 /**
+ * Batch assert for one or more cases with the given comparator.
+ *
  * Print message if test fail.
  *
  * @param string $test
+ * @param callable $comp
  * @param array $cases
  * @return bool
  */
-function batch_assert($test, ...$cases) {
+function batch_assert_ex($test, $comp, ...$cases) {
     foreach ($cases as $case) {
         [$expected, $got] = $case;
-        if ($expected == $got) {
+        if ($comp($expected, $got)) {
             continue;
         }
         echo "Test for $test failed.\n";
@@ -22,3 +25,16 @@ function batch_assert($test, ...$cases) {
     }
     return true;
 }
+
+/**
+ * Batch assert with default comparator.
+ *
+ * @param string $test
+ * @param array $cases
+ * @return bool
+ */
+function batch_assert($test, ...$cases) {
+    return batch_assert_ex($test, function ($expected, $got) {
+        return $expected == $got;
+    }, ...$cases);
+}
diff --git a/tests/includes/supports.php b/tests/includes/supports.php
index 1525968..5337b11 100644
--- a/tests/includes/supports.php
+++ b/tests/includes/supports.php
@@ -1,14 +1,34 @@
 <?php
 
+/**
+ * Check whether the current php-armadillo build supports certain feature.
+ *
+ * @param bool $feature
+ * @param string $msg
+ * @return bool
+ */
+function arma_supports($feature, $msg) {
+    if (!$feature) {
+        echo "skip $msg is not supported.";
+        return false;
+    }
+    return true;
+}
+
 /**
  * Check whether operator overloading is supported.
  *
  * @return bool
  */
 function supports_operator_overloading() {
-    if (!Arma\Features::OPERATORS) {
-        echo 'skip operator overloading is not supported.';
-        return false;
-    }
-    return true;
+    return arma_supports(Arma\Features::OPERATORS, 'operator overloading');
+}
+
+/**
+ * Check whether HDF5 data format is supported.
+ *
+ * @return bool
+ */
+function supports_hdf5() {
+    return arma_supports(Arma\Features::HDF5, 'HDF5 data format');
 }