diff --git a/tests/phpunit/tests/pluggable.php b/tests/phpunit/tests/pluggable.php
new file mode 100644
index 0000000000..464638d761
--- /dev/null
+++ b/tests/phpunit/tests/pluggable.php
@@ -0,0 +1,142 @@
+<?php
+
+/**
+ * @group pluggable
+ */
+class Tests_Pluggable extends WP_UnitTestCase {
+
+	/**
+	 * Tests that the signatures of all functions in pluggable.php match their expected signature.
+	 *
+	 * @ticket 33654
+	 * @ticket 33867
+	 *
+	 * @dataProvider getDefinedPluggableFunctions
+	 */
+	public function testPluggableFunctionSignaturesMatch( $function ) {
+
+		$signatures = $this->getPluggableFunctionSignatures();
+
+		$this->assertTrue( function_exists( $function ) );
+		$this->assertArrayHasKey( $function, $signatures );
+
+		$function_ref = new ReflectionFunction( $function );
+		$param_refs   = $function_ref->getParameters();
+
+		$this->assertSame( count( $signatures[ $function ] ), count( $param_refs ) );
+
+		$i = 0;
+
+		foreach ( $signatures[ $function ] as $name => $value ) {
+
+			$param_ref = $param_refs[ $i ];
+			$msg       = 'Parameter: ' . $param_ref->getName();
+
+			if ( is_numeric( $name ) ) {
+				$name = $value;
+				$this->assertFalse( $param_ref->isOptional(), $msg );
+			} else {
+				$this->assertTrue( $param_ref->isOptional(), $msg );
+				$this->assertSame( $value, $param_ref->getDefaultValue(), $msg );
+			}
+
+			$this->assertSame( $name, $param_ref->getName(), $msg );
+
+			$i++;
+
+		}
+
+	}
+
+	/**
+	 * Test the tests. Makes sure all the expected pluggable functions exist and that they live in pluggable.php.
+	 *
+	 * @ticket 33654
+	 * @ticket 33867
+	 */
+	public function testAllPluggableFunctionsExist() {
+
+		$defined  = wp_list_pluck( $this->getDefinedPluggableFunctions(), 0 );
+		$expected = $this->getPluggableFunctionSignatures();
+
+		foreach ( $expected as $function => $sig ) {
+			$msg = 'Function: ' . $function . '()';
+			$this->assertTrue( function_exists( $function ), $msg );
+			$this->assertTrue( in_array( $function, $defined, true ), $msg );
+		}
+
+	}
+
+	/**
+	 * Data provider for our pluggable function signature tests.
+	 *
+	 * @return array Data provider array of pluggable function names.
+	 */
+	public function getDefinedPluggableFunctions() {
+
+		preg_match_all( '#^function (\w+)#m', file_get_contents( ABSPATH . '/wp-includes/pluggable.php' ), $functions );
+
+		$data = array();
+
+		foreach ( $functions[1] as $function ) {
+			$data[] = array(
+				$function,
+			);
+		}
+
+		return $data;
+
+	}
+
+	/**
+	 * Expected pluggable function signatures.
+	 *
+	 * @return array Array of signatures keyed by their function name.
+	 */
+	public function getPluggableFunctionSignatures() {
+
+		return array(
+			'wp_set_current_user'             => array( 'id', 'name' => '' ),
+			'wp_get_current_user'             => array(),
+			'get_currentuserinfo'             => array(),
+			'get_userdata'                    => array( 'user_id' ),
+			'get_user_by'                     => array( 'field', 'value' ),
+			'cache_users'                     => array( 'user_ids' ),
+			'wp_mail'                         => array( 'to', 'subject', 'message', 'headers' => '', 'attachments' => array() ),
+			'wp_authenticate'                 => array( 'username', 'password' ),
+			'wp_logout'                       => array(),
+			'wp_validate_auth_cookie'         => array( 'cookie' => '', 'scheme' => '' ),
+			'wp_generate_auth_cookie'         => array( 'user_id', 'expiration', 'scheme' => 'auth', 'token' => '' ),
+			'wp_parse_auth_cookie'            => array( 'cookie' => '', 'scheme' => '' ),
+			'wp_set_auth_cookie'              => array( 'user_id', 'remember' => false, 'secure' => '', 'token' => '' ),
+			'wp_clear_auth_cookie'            => array(),
+			'is_user_logged_in'               => array(),
+			'auth_redirect'                   => array(),
+			'check_admin_referer'             => array( 'action' => -1, 'query_arg' => '_wpnonce' ),
+			'check_ajax_referer'              => array( 'action' => -1, 'query_arg' => false, 'die' => true ),
+			'wp_redirect'                     => array( 'location', 'status' => 302 ),
+			'wp_sanitize_redirect'            => array( 'location' ),
+			'_wp_sanitize_utf8_in_redirect'   => array( 'matches' ),
+			'wp_safe_redirect'                => array( 'location', 'status' => 302 ),
+			'wp_validate_redirect'            => array( 'location', 'default' => '' ),
+			'wp_notify_postauthor'            => array( 'comment_id', 'deprecated' => null ),
+			'wp_notify_moderator'             => array( 'comment_id' ),
+			'wp_password_change_notification' => array( 'user' ),
+			'wp_new_user_notification'        => array( 'user_id', 'deprecated' => null, 'notify' => '' ),
+			'wp_nonce_tick'                   => array(),
+			'wp_verify_nonce'                 => array( 'nonce', 'action' => -1 ),
+			'wp_create_nonce'                 => array( 'action' => -1 ),
+			'wp_salt'                         => array( 'scheme' => 'auth' ),
+			'wp_hash'                         => array( 'data', 'scheme' => 'auth' ),
+			'wp_hash_password'                => array( 'password' ),
+			'wp_check_password'               => array( 'password', 'hash', 'user_id' => '' ),
+			'wp_generate_password'            => array( 'length' => 12, 'special_chars' => true, 'extra_special_chars' => false ),
+			'wp_rand'                         => array( 'min' => 0, 'max' => 0 ),
+			'wp_set_password'                 => array( 'password', 'user_id' ),
+			'get_avatar'                      => array( 'id_or_email', 'size' => 96, 'default' => '', 'alt' => '', 'args' => null ),
+			'wp_text_diff'                    => array( 'left_string', 'right_string', 'args' => null ),
+		);
+
+	}
+
+}