diff --git a/phpunit.xml b/phpunit.xml
index f255df3..1e26142 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,12 +1,13 @@
-<phpunit bootstrap="tests/Helpers.php" backupGlobals="false" colors="true">
+<?xml version="1.0"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="tests/Helpers.php" backupGlobals="false" colors="true" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage includeUncoveredFiles="true">
+    <include>
+      <directory suffix=".php">src</directory>
+    </include>
+  </coverage>
   <testsuites>
     <testsuite name="unit_and_integration">
       <directory suffix="_test.php">tests</directory>
     </testsuite>
   </testsuites>
-  <filter>
-    <whitelist addUncoveredFilesFromWhitelist="true">
-      <directory suffix=".php">src</directory>
-    </whitelist>
-  </filter>
 </phpunit>
diff --git a/spec/dependencies/dependency_types.spec.php b/spec/dependencies/dependency_types.spec.php
new file mode 100644
index 0000000..1aae91d
--- /dev/null
+++ b/spec/dependencies/dependency_types.spec.php
@@ -0,0 +1,9 @@
+<?php
+
+describe(\Dxw\Whippet\Dependencies\DependencyTypes::class, function () {
+	context("getDependencyTypes()", function () {
+		it('returns a list of dependencies as strings', function () {
+			expect(\Dxw\Whippet\Dependencies\DependencyTypes::getDependencyTypes())->toBe(['themes', 'plugins']);
+		});
+	});
+});
diff --git a/src/Dependencies/DependencyTypes.php b/src/Dependencies/DependencyTypes.php
new file mode 100644
index 0000000..e3de5af
--- /dev/null
+++ b/src/Dependencies/DependencyTypes.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Dxw\Whippet\Dependencies;
+
+class DependencyTypes
+{
+	public const PLUGINS = 'plugins';
+	public const THEMES = 'themes';
+
+
+	public static function getDependencyTypes()
+	{
+
+		return [DependencyTypes::THEMES, DependencyTypes::PLUGINS];
+	}
+}
diff --git a/src/Dependencies/Describer.php b/src/Dependencies/Describer.php
index ab6e788..f710db5 100644
--- a/src/Dependencies/Describer.php
+++ b/src/Dependencies/Describer.php
@@ -22,10 +22,9 @@ public function describe()
 		if ($resultLoad->isErr()) {
 			return $resultLoad;
 		}
-		$dependencyTypes = ['themes', 'plugins'];
 		$git = new \Dxw\Whippet\Git\Git($this->dir);
 		$results = [];
-		foreach ($dependencyTypes as $type) {
+		foreach (DependencyTypes::getDependencyTypes() as $type) {
 			foreach ($this->lockFile->getDependencies($type) as $dep) {
 				$result = $git::tag_for_commit($dep['src'], $dep['revision']);
 				if ($result->isErr()) {
diff --git a/src/Dependencies/Installer.php b/src/Dependencies/Installer.php
index f837db2..e76475c 100644
--- a/src/Dependencies/Installer.php
+++ b/src/Dependencies/Installer.php
@@ -28,7 +28,7 @@ public function installAll()
 
 		$dependencies = [];
 
-		foreach (['themes', 'plugins'] as $type) {
+		foreach (DependencyTypes::getDependencyTypes() as $type) {
 			$dependencies[$type] = $this->lockFile->getDependencies($type);
 		}
 
diff --git a/src/Dependencies/Updater.php b/src/Dependencies/Updater.php
index 37cba7e..d7977dc 100644
--- a/src/Dependencies/Updater.php
+++ b/src/Dependencies/Updater.php
@@ -57,7 +57,7 @@ public function updateAll()
 
 		$allDependencies = [];
 
-		foreach (['themes', 'plugins'] as $type) {
+		foreach (DependencyTypes::getDependencyTypes() as $type) {
 			$allDependencies[$type] = $this->jsonFile->getDependencies($type);
 		}
 
@@ -133,7 +133,7 @@ private function updateHash()
 
 	private function createGitIgnore()
 	{
-		foreach (['themes', 'plugins'] as $type) {
+		foreach (DependencyTypes::getDependencyTypes() as $type) {
 			foreach ($this->jsonFile->getDependencies($type) as $dep) {
 				$this->addDependencyToIgnoresArray($type, $dep['name']);
 			}
@@ -151,7 +151,7 @@ private function loadGitignore()
 		}
 
 		// Iterate through locked dependencies and remove from gitignore
-		foreach (['themes', 'plugins'] as $type) {
+		foreach (DependencyTypes::getDependencyTypes() as $type) {
 			foreach ($this->lockFile->getDependencies($type) as $dep) {
 				$line = $this->getGitignoreDependencyLine($type, $dep['name']);
 				$index = array_search($line, $this->ignores);
diff --git a/src/Dependencies/Validator.php b/src/Dependencies/Validator.php
index 17ab56d..209638e 100644
--- a/src/Dependencies/Validator.php
+++ b/src/Dependencies/Validator.php
@@ -46,7 +46,7 @@ public function validate(bool $enforceRefs = false)
 
 		// Check that entries in whippet.json
 		// match entries in whippet.lock
-		foreach (['themes', 'plugins'] as $type) {
+		foreach (DependencyTypes::getDependencyTypes() as $type) {
 			$whippetJsonDependencies = $whippetJson->getDependencies($type);
 			$whippetLockDependencies = $whippetLock->getDependencies($type);
 			if (count($whippetJsonDependencies) !== count($whippetLockDependencies)) {
diff --git a/src/Git/Gitignore.php b/src/Git/Gitignore.php
index 9c6c97b..b37fffb 100644
--- a/src/Git/Gitignore.php
+++ b/src/Git/Gitignore.php
@@ -45,7 +45,7 @@ public function save_ignores($ignores)
 	private function ensure_closing_newline($ignores)
 	{
 		$index_of_last_line = count($ignores) - 1;
-		$last_line = $ignores[$index_of_last_line];
+		$last_line = $index_of_last_line >= 0 ? $ignores[$index_of_last_line] : 0;
 		$last_character = substr($last_line, -1);
 
 		if ($last_character != "\n") {
diff --git a/tests/services/inspection_checker_test.php b/tests/services/inspection_checker_test.php
index 5f0c187..ba3022e 100644
--- a/tests/services/inspection_checker_test.php
+++ b/tests/services/inspection_checker_test.php
@@ -35,7 +35,8 @@ public function testPluginCallsAPI()
 			'revision' => '123456',
 		];
 		$checker = new \Dxw\Whippet\Services\InspectionChecker($api);
-		$checker->check('plugins', $my_plugin);
+		$result = $checker->check('plugins', $my_plugin);
+		$this->assertFalse($result->isErr());
 	}
 
 	public function testPluginWithNoInspectionsGeneratesMessage()
diff --git a/tests/services/inspections_api_test.php b/tests/services/inspections_api_test.php
index 3221c82..6e43bfe 100644
--- a/tests/services/inspections_api_test.php
+++ b/tests/services/inspections_api_test.php
@@ -16,7 +16,9 @@ public function testCallsApi()
 			->andReturn(\Result\Result::ok([]));
 
 		$api = new \Dxw\Whippet\Services\InspectionsApi('https://advisories.dxw.com', '/wp-json/v1/inspections/', $json_api);
-		$api->getInspections('my-plugin');
+		$result = $api->getInspections('my-plugin');
+		$this->assertFalse($result->isErr());
+		$this->assertEquals([], $result->unwrap());
 	}
 
 	public function testNoInspections()
diff --git a/tests/services/json_api_test.php b/tests/services/json_api_test.php
index f4a3dd0..3adbb90 100644
--- a/tests/services/json_api_test.php
+++ b/tests/services/json_api_test.php
@@ -16,7 +16,9 @@ public function testCallsApi()
 			->andReturn(\Result\Result::ok('[]'));
 
 		$api = new \Dxw\Whippet\Services\JsonApi($base_api);
-		$api->get('http://apisite.com/api/endpoint');
+		$result = $api->get('http://apisite.com/api/endpoint');
+		$this->assertFalse($result->isErr());
+		$this->assertEquals([], $result->unwrap());
 	}
 
 	public function testEmptyResponse()