diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 749e6d0..711d813 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -4,4 +4,8 @@ PHP 5.3 - PHPUnit:
 
 PHP 7.2 - PHPUnit:
   script: "ci/php72.sh $CI_PROJECT_DIR"
+  image: "registry.gitlab.com/hpierce1102/classfinder/php72"
+
+PHP 7.2 - No Autoloader Property:
+  script: "ci/php72-no-autoload.sh $CI_PROJECT_DIR"
   image: "registry.gitlab.com/hpierce1102/classfinder/php72"
\ No newline at end of file
diff --git a/ci/php72-no-autoload.sh b/ci/php72-no-autoload.sh
new file mode 100644
index 0000000..4cf7f55
--- /dev/null
+++ b/ci/php72-no-autoload.sh
@@ -0,0 +1,4 @@
+composer install --working-dir=$1/test/app2 --quiet || exit 1
+composer install --working-dir=$1 --quiet || exit 1
+php --version
+php $1/vendor/bin/phpunit --testsuite noAutoload
\ No newline at end of file
diff --git a/phpunit.xml b/phpunit.xml
index 7765f0f..f518ded 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -25,5 +25,9 @@
             <file>test/app1/src/FilesTest.php</file>
             <directory>test/unit/Files</directory>
         </testsuite>
+        <testsuite name="noAutoload">
+            <file>test/app2/PSR4NoAutoloadTest.php</file>
+            <file>test/app2/ClassmapNoAutoloadTest.php</file>
+        </testsuite>
     </testsuites>
 </phpunit>
\ No newline at end of file
diff --git a/test/app2/ClassmapNoAutoloadTest.php b/test/app2/ClassmapNoAutoloadTest.php
new file mode 100644
index 0000000..3dfeca8
--- /dev/null
+++ b/test/app2/ClassmapNoAutoloadTest.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace TestApp1;
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+use HaydenPierce\ClassFinder\ClassFinder;
+
+class ClassmapTest extends \PHPUnit_Framework_TestCase
+{
+    public function setup()
+    {
+        // Reset ClassFinder back to normal.
+        ClassFinder::setAppRoot(null);
+    }
+    /**
+     * @dataProvider classFinderDataProvider
+     */
+    public function testClassFinder($namespace, $expected, $message)
+    {
+        try {
+            $classes = ClassFinder::getClassesInNamespace($namespace);
+        } catch (Exception $e) {
+            $this->assertFalse(true, 'An exception occurred: ' . $e->getMessage());
+            $classes = array();
+        }
+
+        $this->assertEquals($expected, $classes, $message);
+    }
+
+    public function classFinderDataProvider()
+    {
+        return array(
+            array(
+                'HaydenPierce\Classmap',
+                array(
+                    'HaydenPierce\Classmap\Classmap2ClassmapINC',
+                    'HaydenPierce\Classmap\Classmap2ClassmapPHP',
+                    'HaydenPierce\Classmap\Classmap3ClassesPHP',
+                    'HaydenPierce\Classmap\ClassmapClassmap2PHP'
+                ),
+                'Classfinder should be able to load classes based on a classmap from 3rd party packages.'
+            ),
+            array(
+                'HaydenPierce\Classmap2',
+                array(
+                    'HaydenPierce\Classmap2\Classmap2ClassmapINC',
+                    'HaydenPierce\Classmap2\Classmap2ClassmapPHP',
+                    'HaydenPierce\Classmap2\Classmap3ClassesPHP',
+                    'HaydenPierce\Classmap2\ClassmapClassmap2PHP'
+                ),
+                'Classfinder should be able to handle multiple namespaces in a single file for a classmap.'
+            )
+        );
+    }
+
+    /**
+     * @dataProvider classesInNamespaceRecursivelyDataProvider
+     */
+    public function testClassesInNamespaceRecursively($namespace, $expected, $message)
+    {
+        ClassFinder::disablePSR4Support();
+
+        try {
+            $classes = ClassFinder::getClassesInNamespace($namespace, ClassFinder::RECURSIVE_MODE);
+        } catch (Exception $e) {
+            $this->assertFalse(true, 'An exception occurred: ' . $e->getMessage());
+            $classes = array();
+        }
+
+        ClassFinder::enablePSR4Support();
+
+        $this->assertEquals($expected, $classes, $message);
+    }
+
+    public function classesInNamespaceRecursivelyDataProvider()
+    {
+        return array(
+            array(
+                'HaydenPierce',
+                array(
+                    'HaydenPierce\Classmap2\Classmap2ClassmapINC',
+                    'HaydenPierce\Classmap2\Classmap2ClassmapPHP',
+                    'HaydenPierce\Classmap2\Classmap3ClassesPHP',
+                    'HaydenPierce\Classmap2\ClassmapClassmap2PHP',
+                    'HaydenPierce\Classmap\Classmap2ClassmapINC',
+                    'HaydenPierce\Classmap\Classmap2ClassmapPHP',
+                    'HaydenPierce\Classmap\Classmap3ClassesPHP',
+                    'HaydenPierce\Classmap\ClassmapClassmap2PHP',
+                ),
+                'Classfinder should be able to load third party classes recursively based on a classmap.'
+            )
+        );
+    }
+}
\ No newline at end of file
diff --git a/test/app2/PSR4NoAutoloadTest.php b/test/app2/PSR4NoAutoloadTest.php
new file mode 100644
index 0000000..bcfee0c
--- /dev/null
+++ b/test/app2/PSR4NoAutoloadTest.php
@@ -0,0 +1,104 @@
+<?php
+
+namespace TestApp1;
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+use HaydenPierce\ClassFinder\ClassFinder;
+
+class PSR4NoAutoloadTest extends \PHPUnit_Framework_TestCase
+{
+    public function setup()
+    {
+        // Reset ClassFinder back to normal.
+        ClassFinder::setAppRoot(null);
+    }
+
+    /**
+     * @dataProvider getClassesInNamespaceDataProvider
+     */
+    public function testGetClassesInNamespace($namespace, $expected, $message)
+    {
+        try {
+            $classes = ClassFinder::getClassesInNamespace($namespace);
+        } catch (\Exception $e) {
+            $this->assertFalse(true, 'An exception occurred: ' . $e->getMessage());
+            $classes = array();
+        }
+
+        $this->assertEquals($expected, $classes, $message);
+    }
+
+    public function getClassesInNamespaceDataProvider()
+    {
+        return array(
+            array(
+                'HaydenPierce\SandboxApp',
+                array(
+                    'HaydenPierce\SandboxApp\Foy'
+                ),
+                'ClassFinder should be able to find 3rd party classes'
+            ),
+            array(
+                'HaydenPierce\SandboxApp\Foo\Bar',
+                array(
+                    'HaydenPierce\SandboxApp\Foo\Bar\Barc',
+                    'HaydenPierce\SandboxApp\Foo\Bar\Barp'
+                ),
+                'ClassFinder should be able to find 3rd party classes multiple namespaces deep.'
+            ),
+            array(
+                'HaydenPierce\SandboxAppMulti',
+                array(
+                    'HaydenPierce\SandboxAppMulti\Zip',
+                    'HaydenPierce\SandboxAppMulti\Zop',
+                    'HaydenPierce\SandboxAppMulti\Zap',
+                    'HaydenPierce\SandboxAppMulti\Zit'
+                ),
+                'ClassFinder should be able to find 3rd party classes when a provided namespace root maps to multiple directories (Example: "HaydenPierce\\SandboxAppMulti\\": ["multi/Bop", "multi/Bot"] )'
+            ),
+            array(
+                'TestApp1\Foo\Empty',
+                array(),
+                'ClassFinder should return an empty array if the namespace is known, but contains no classes.'
+            )
+        );
+    }
+
+    public function testGetClassesInNamespaceRecursively()
+    {
+        $namespace = 'HaydenPierce';
+        $expected = array(
+            'HaydenPierce\SandboxApp\Foy',
+            'HaydenPierce\SandboxApp\Fob\Soz',
+            'HaydenPierce\SandboxApp\Foo\Larc',
+            'HaydenPierce\SandboxApp\Foo\Bar\Barc',
+            'HaydenPierce\SandboxApp\Foo\Bar\Barp',
+            'HaydenPierce\SandboxAppMulti\Zip',
+            'HaydenPierce\SandboxAppMulti\Zop',
+            'HaydenPierce\SandboxAppMulti\Zap',
+            'HaydenPierce\SandboxAppMulti\Zit'
+        );
+        $message = 'ClassFinder should be able to find 3rd party classes';
+
+        ClassFinder::disableClassmapSupport();
+
+        try {
+            $classes = ClassFinder::getClassesInNamespace($namespace, ClassFinder::RECURSIVE_MODE);
+        } catch (\Exception $e) {
+            $this->assertFalse(true, 'An exception occurred: ' . $e->getMessage());
+            $classes = array();
+        }
+
+        // ClassFinder has the ability to find itself. This ability, while intended, is incontinent for tests
+        // because of the 'HaydenPierce' test case. Whenever ClassFinder would be updated, we would need to update the
+        // test. To prevent the flakiness, we just remove ClassFinder's classes.
+        $classes = array_filter($classes, function($class) {
+            return strpos($class, 'HaydenPierce\ClassFinder') !== 0;
+        });
+
+        ClassFinder::enableClassmapSupport();
+
+        $this->assertEquals($expected, $classes, $message);
+    }
+}
\ No newline at end of file
diff --git a/test/app2/README.md b/test/app2/README.md
new file mode 100644
index 0000000..4e9cf03
--- /dev/null
+++ b/test/app2/README.md
@@ -0,0 +1,3 @@
+This test app tests that ClassFinder is working in applications that do't specify their own autoload configs in composer.json.
+
+This can occur when ClassFinder is used only to retrieve 3rd party dependencies.
\ No newline at end of file
diff --git a/test/app2/composer.json b/test/app2/composer.json
new file mode 100644
index 0000000..5425005
--- /dev/null
+++ b/test/app2/composer.json
@@ -0,0 +1,16 @@
+{
+  "name": "HaydenPierce/testApp",
+  "type": "project",
+  "license": "MIT",
+  "authors": [
+    {
+      "name": "Hayden Pierce",
+      "email": "hayden@haydenpierce.com"
+    }
+  ],
+  "require-dev": {
+    "phpunit/phpunit": "4.8.36",
+    "haydenpierce/class-finder": "0.0.1",
+    "haydenpierce/sandbox-app":"0.3.0"
+  }
+}