add throwsIf exception

src/PendingObjects/TestCall.php

@@ -78,6 +78,26 @@ final class TestCall
         return $this;
     }
 
+    /**
+     * Asserts that the test throws the given `$exceptionClass` when called if the given condition is true.
+     *
+     * @param Closure|bool|int $condition
+     */
+    public function throwsIf($condition, string $exception, string $exceptionMessage = null): TestCall
+    {
+        $condition = is_callable($condition)
+            ? $condition
+            : Closure::fromCallable(function () use ($condition): bool {
+                return (bool) $condition;
+            });
+
+        if ($condition() === true) {
+            return $this->throws($exception, $exceptionMessage);
+        }
+
+        return $this;
+    }
+
     /**
      * Runs the current test multiple times with
      * each item of the given `iterable`.