depends.py: enable key exchange tests

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/tests/scripts/depends.py b/tests/scripts/depends.py
index d4fe4fd..5714f9a 100755
--- a/tests/scripts/depends.py
+++ b/tests/scripts/depends.py
@@ -421,9 +421,7 @@
                                           '|MBEDTLS_SHA384_'),
             # Key exchange types. Only build the library and the sample
             # programs.
-            'kex': ExclusiveDomain(key_exchange_symbols,
-                                   [build_command + ['lib'],
-                                    build_command + ['-C', 'programs']]),
+            'kex': ExclusiveDomain(key_exchange_symbols, build_and_test),
             'pkalgs': ComplementaryDomain(['MBEDTLS_ECDSA_C',
                                            'MBEDTLS_ECP_C',
                                            'MBEDTLS_PKCS1_V21',