diff --git a/tests/Psl/Type/IsBoolTest.php b/tests/Psl/Type/IsBoolTest.php
new file mode 100644
index 00000000..035a428e
--- /dev/null
+++ b/tests/Psl/Type/IsBoolTest.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Type;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Math;
+use Psl\Type;
+
+final class IsBoolTest extends TestCase
+{
+    public function testIsBool(): void
+    {
+        static::assertTrue(Type\is_bool(true));
+
+        static::assertFalse(Type\is_bool(123));
+        static::assertFalse(Type\is_bool(0));
+        static::assertFalse(Type\is_bool(Math\INT16_MAX));
+        static::assertFalse(Type\is_bool('5'));
+        static::assertFalse(Type\is_bool(null));
+        static::assertFalse(Type\is_bool(5.0));
+    }
+}
diff --git a/tests/Psl/Type/IsFloatTest.php b/tests/Psl/Type/IsFloatTest.php
new file mode 100644
index 00000000..75c786b2
--- /dev/null
+++ b/tests/Psl/Type/IsFloatTest.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Type;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Math;
+use Psl\Type;
+
+final class IsFloatTest extends TestCase
+{
+    public function testIsFloat(): void
+    {
+        static::assertTrue(Type\is_float(5.0));
+
+        static::assertFalse(Type\is_float(123));
+        static::assertFalse(Type\is_float(0));
+        static::assertFalse(Type\is_float(Math\INT16_MAX));
+        static::assertFalse(Type\is_float('5'));
+        static::assertFalse(Type\is_float(true));
+        static::assertFalse(Type\is_float(null));
+    }
+}
diff --git a/tests/Psl/Type/IsNullTest.php b/tests/Psl/Type/IsNullTest.php
new file mode 100644
index 00000000..6446185f
--- /dev/null
+++ b/tests/Psl/Type/IsNullTest.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Type;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Math;
+use Psl\Type;
+
+final class IsNullTest extends TestCase
+{
+    public function testIsNull(): void
+    {
+        static::assertTrue(Type\is_null(null));
+
+        static::assertFalse(Type\is_null(123));
+        static::assertFalse(Type\is_null(0));
+        static::assertFalse(Type\is_null(Math\INT16_MAX));
+        static::assertFalse(Type\is_null('5'));
+        static::assertFalse(Type\is_null(true));
+        static::assertFalse(Type\is_null(5.0));
+    }
+}
diff --git a/tests/Psl/Type/IsResourceTest.php b/tests/Psl/Type/IsResourceTest.php
new file mode 100644
index 00000000..2fac0337
--- /dev/null
+++ b/tests/Psl/Type/IsResourceTest.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Type;
+
+use PHPUnit\Framework\TestCase;
+use Psl\Math;
+use Psl\Type;
+
+use const STDOUT;
+
+final class IsResourceTest extends TestCase
+{
+    public function testIsResource(): void
+    {
+        static::assertTrue(Type\is_resource(STDOUT));
+
+        static::assertFalse(Type\is_resource(null));
+        static::assertFalse(Type\is_resource(123));
+        static::assertFalse(Type\is_resource(0));
+        static::assertFalse(Type\is_resource(Math\INT16_MAX));
+        static::assertFalse(Type\is_resource('5'));
+        static::assertFalse(Type\is_resource(true));
+        static::assertFalse(Type\is_resource(5.0));
+    }
+}