diff --git a/RoboFile.php b/RoboFile.php
index 93c9444..e47c8fc 100644
--- a/RoboFile.php
+++ b/RoboFile.php
@@ -126,7 +126,7 @@ class RoboFile extends \Robo\Tasks {
         $execpath = norm(BASE."vendor-bin/phpunit/vendor/phpunit/phpunit/phpunit");
         $confpath = realpath(BASE_TEST."phpunit.dist.xml") ?: norm(BASE_TEST."phpunit.xml");
         $this->taskServer(8000)->host("localhost")->dir(BASE_TEST."docroot")->rawArg("-n")->arg(BASE_TEST."server.php")->rawArg($this->blackhole())->background()->run();
-        return $this->taskExec($executor)->arg($execpath)->option("-c", $confpath)->args(array_merge($set, $args))->run();
+        return $this->taskExec($executor)->option("-d", "zend.assertions=1")->arg($execpath)->option("-c", $confpath)->args(array_merge($set, $args))->run();
     }
 
     /** Packages a given commit of the software into a release tarball
diff --git a/lib/Database.php b/lib/Database.php
index 71febcc..3752403 100644
--- a/lib/Database.php
+++ b/lib/Database.php
@@ -198,13 +198,11 @@ class Database {
      * @param boolean $matchAny Whether the search is successful when it matches any (true) or all (false) terms
      */
     protected function generateSearch(array $terms, array $cols, bool $matchAny = false): array {
-        if (!$cols) {
-            throw new Exception("arrayEmpty", "cols"); // @codeCoverageIgnore
-        }
         $clause = [];
         $types = [];
         $values = [];
         $like = $this->db->sqlToken("like");
+        assert(sizeof($cols) > 0, new Exception("arrayEmpty", "cols"));
         $embedSet = sizeof($terms) > ((int) (self::LIMIT_SET_SIZE / sizeof($cols)));
         foreach ($terms as $term) {
             $embedTerm = ($embedSet && strlen($term) <= self::LIMIT_SET_STRING_LENGTH);
@@ -2081,9 +2079,7 @@ class Database {
      * @param boolean $byName Whether to interpret the $id parameter as the label's name (true) or identifier (false)
      */
     public function labelArticlesSet(string $user, $id, Context $context, int $mode = self::ASSOC_ADD, bool $byName = false): int {
-        if (!in_array($mode, [self::ASSOC_ADD, self::ASSOC_REMOVE, self::ASSOC_REPLACE])) {
-            throw new Exception("constantUnknown", $mode); // @codeCoverageIgnore
-        }
+        assert(in_array($mode, [self::ASSOC_ADD, self::ASSOC_REMOVE, self::ASSOC_REPLACE]), new Exception("constantUnknown", $mode));
         if (!Arsse::$user->authorize($user, __FUNCTION__)) {
             throw new User\ExceptionAuthz("notAuthorized", ["action" => __FUNCTION__, "user" => $user]);
         }
@@ -2386,9 +2382,7 @@ class Database {
      * @param boolean $byName Whether to interpret the $id parameter as the tag's name (true) or identifier (false)
      */
     public function tagSubscriptionsSet(string $user, $id, array $subscriptions, int $mode = self::ASSOC_ADD, bool $byName = false): int {
-        if (!in_array($mode, [self::ASSOC_ADD, self::ASSOC_REMOVE, self::ASSOC_REPLACE])) {
-            throw new Exception("constantUnknown", $mode); // @codeCoverageIgnore
-        }
+        assert(in_array($mode, [self::ASSOC_ADD, self::ASSOC_REMOVE, self::ASSOC_REPLACE]), new Exception("constantUnknown", $mode));
         if (!Arsse::$user->authorize($user, __FUNCTION__)) {
             throw new User\ExceptionAuthz("notAuthorized", ["action" => __FUNCTION__, "user" => $user]);
         }
diff --git a/lib/Db/AbstractStatement.php b/lib/Db/AbstractStatement.php
index abf9f77..cc8ce42 100644
--- a/lib/Db/AbstractStatement.php
+++ b/lib/Db/AbstractStatement.php
@@ -56,9 +56,7 @@ abstract class AbstractStatement implements Statement {
                 $this->retypeArray($binding, true);
             } else {
                 $bindId = self::TYPES[trim(strtolower($binding))] ?? 0;
-                if (!$bindId) {
-                    throw new Exception("paramTypeInvalid", $binding); // @codeCoverageIgnore
-                }
+                assert($bindId, new Exception("paramTypeInvalid", $binding));
                 $this->types[] = $bindId;
             }
         }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 68c7ea8..33dac91 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -10,5 +10,7 @@ const NS_BASE = __NAMESPACE__."\\";
 define(NS_BASE."BASE", dirname(__DIR__).DIRECTORY_SEPARATOR);
 const DOCROOT = BASE."tests".DIRECTORY_SEPARATOR."docroot".DIRECTORY_SEPARATOR;
 ini_set("memory_limit", "-1");
+ini_set("zend.assertions", "1");
+ini_set("assert.exception", "true");
 error_reporting(\E_ALL);
 require_once BASE."vendor".DIRECTORY_SEPARATOR."autoload.php";