diff --git a/testing.rst b/testing.rst
index 1fe8e409a69..00103c6f48c 100644
--- a/testing.rst
+++ b/testing.rst
@@ -922,6 +922,8 @@ Browser Assertions
 ``assertBrowserCookieValueSame(string $name, string $expectedValue, string $path = '/', string $domain = null, string $message = '')``
     Asserts the given cookie in the test Client is set to the expected
     value.
+``assertThatForClient(Constraint $constraint, string $message = '')``
+    Asserts the given Constraint in Client.
 
 Crawler Assertions
 ..................