diff --git a/lib/Catcher/ThrowableController.php b/lib/Catcher/ThrowableController.php
index 53b1b5e..0341ede 100644
--- a/lib/Catcher/ThrowableController.php
+++ b/lib/Catcher/ThrowableController.php
@@ -93,7 +93,7 @@ class ThrowableController {
             return $this->frames;
         }
         if ($argFrameLimit < 0) {
-            throw new \RangeException('Argument argFrameLimit cannot be less than 0');
+            throw new UnderflowException('Argument argFrameLimit cannot be less than 0');
         }
 
         if (
diff --git a/tests/cases/TestThrowableController.php b/tests/cases/TestThrowableController.php
new file mode 100644
index 0000000..d0b9eac
--- /dev/null
+++ b/tests/cases/TestThrowableController.php
@@ -0,0 +1,143 @@
+<?php
+/**
+ * @license MIT
+ * Copyright 2022 Dustin Wilson, et al.
+ * See LICENSE and AUTHORS files for details
+ */
+
+declare(strict_types=1);
+namespace MensBeam\Catcher\Test;
+use MensBeam\Catcher\{
+    Error,
+    ThrowableController,
+    UnderflowException
+};
+
+
+/** @covers \MensBeam\Catcher\ThrowableController */
+class TestThrowableController extends \PHPUnit\Framework\TestCase {
+
+    /** @dataProvider provideErrorTypeTests */
+    public function testErrorTypes(\Throwable $throwable, ?string $expectedType = null): void {
+        $c = new ThrowableController($throwable);
+        $this->assertSame($expectedType, $c->getErrorType());
+        // Tests caching
+        $this->assertSame($expectedType, $c->getErrorType());
+    }
+
+    /** @dataProvider provideGettingFramesTests */
+    public function testGettingFrames(\Throwable $throwable): void {
+        $c = new ThrowableController($throwable);
+        $f = $c->getFrames(rand(0, 10));
+        $this->assertNotNull($f);
+        $this->assertGreaterThan(0, count($f));
+        // Tests caching
+        $this->assertNotNull($c->getFrames());
+    }
+
+    /** @dataProvider provideGettingFramesInCallUserFuncTests */
+    public function testGettingFramesInCallUserFunc(\Closure $closure): void {
+        $f = false;
+        try {
+            $closure();
+            call_user_func_array(function() {
+                throw new \Exception('Ook!');
+            }, []);
+        } catch (\Throwable $t) {
+            $c = new ThrowableController($t);
+            $f = $c->getFrames();
+        } finally {
+            $this->assertNotNull($f);
+            $this->assertGreaterThan(0, count($f));
+        }
+    }
+
+    public function testGetPrevious(): void {
+        $t = new ThrowableController(new \Exception(message: 'Ook!', previous: new Error(message: 'Ook!', code: \E_ERROR, previous: new \Exception('Ook!'))));
+        $this->assertInstanceOf(\Exception::class, $t->getThrowable());
+        $t2 = $t->getPrevious();
+        $this->assertInstanceOf(Error::class, $t2->getThrowable());
+        $t3 = $t2->getPrevious();
+        $this->assertInstanceOf(\Exception::class, $t3->getThrowable());
+        // Tests caching
+        $t3 = $t2->getPrevious();
+        $this->assertInstanceOf(\Exception::class, $t3->getThrowable());
+    }
+
+
+    public function testFatalError(): void {
+        $this->expectException(UnderflowException::class);
+        $c = new ThrowableController(new \Exception('ook'));
+        $f = $c->getFrames(-1);
+    }
+
+    public static function provideErrorTypeTests(): iterable {
+        $options = [
+            [ new Error('Ook!', \E_ERROR, '/dev/null', 0), 'PHP Fatal Error' ],
+            [ new Error('Ook!', \E_WARNING, '/dev/null', 0), 'PHP Warning' ],
+            [ new Error('Ook!', \E_PARSE, '/dev/null', 0), 'PHP Parsing Error' ],
+            [ new Error('Ook!', \E_NOTICE, '/dev/null', 0), 'PHP Notice' ],
+            [ new Error('Ook!', \E_CORE_ERROR, '/dev/null', 0), 'PHP Core Error' ],
+            [ new Error('Ook!', \E_CORE_WARNING, '/dev/null', 0), 'PHP Core Warning' ],
+            [ new Error('Ook!', \E_COMPILE_ERROR, '/dev/null', 0), 'Compile Error' ],
+            [ new Error('Ook!', \E_COMPILE_WARNING, '/dev/null', 0), 'Compile Warning' ],
+            [ new Error('Ook!', \E_STRICT, '/dev/null', 0), 'Runtime Notice' ],
+            [ new Error('Ook!', \E_RECOVERABLE_ERROR, '/dev/null', 0), 'Recoverable Error' ],
+            [ new Error('Ook!', \E_DEPRECATED, '/dev/null', 0), 'Deprecated' ],
+            [ new Error('Ook!', \E_USER_DEPRECATED, '/dev/null', 0), 'Deprecated' ],
+            [ new Error('Ook!', \E_USER_ERROR, '/dev/null', 0), 'Fatal Error' ],
+            [ new Error('Ook!', \E_USER_WARNING, '/dev/null', 0), 'Warning' ],
+            [ new Error('Ook!', \E_USER_NOTICE, '/dev/null', 0), 'Notice' ],
+            [ new Error('Ook!', \E_ALL, '/dev/null', 0) ],
+            [ new \Exception('Ook!') ],
+        ];
+
+        foreach ($options as $o) {
+            yield $o;
+        }
+    }
+
+    public static function provideGettingFramesTests(): iterable {
+        $options = [
+            [ new Error('Ook!', \E_ERROR, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_WARNING, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_PARSE, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_NOTICE, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_CORE_ERROR, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_CORE_WARNING, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_COMPILE_ERROR, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_COMPILE_WARNING, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_STRICT, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_RECOVERABLE_ERROR, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_DEPRECATED, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_USER_DEPRECATED, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_USER_ERROR, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_USER_WARNING, '/dev/null', 0) ],
+            [ new Error('Ook!', \E_USER_NOTICE, '/dev/null', 0) ],
+            [ new \Exception('Ook!') ],
+            [ new \Exception(message: 'Ook!', previous: new Error(message: 'Ook!', code: \E_ERROR, previous: new \Exception('Ook!'))) ]
+        ];
+
+        foreach ($options as $o) {
+            yield $o;
+        }
+    }
+
+    public static function provideGettingFramesInCallUserFuncTests(): iterable {
+        $options = [
+            function () {
+                call_user_func_array(function() {
+                    throw new \Exception('Ook!');
+                }, []);
+            },
+            function () {
+                function ook() {}
+                call_user_func('ook', []);
+            }
+        ];
+
+        foreach ($options as $o) {
+            yield [ $o ];
+        }
+    }
+}
\ No newline at end of file