Add explicit mbedtls_ecp_tls_read_group_id call

Signed-off-by: Werner Lewis <werner.lewis@arm.com>
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 586c26c..3ad7e71 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -798,6 +798,7 @@
 {
     mbedtls_ecp_group grp, grp_read, grp_cpy;
     const mbedtls_ecp_group_id *g_id;
+    mbedtls_ecp_group_id read_g_id;
     const mbedtls_ecp_curve_info *crv, *crv_tls_id, *crv_name;
 
     mbedtls_mpi exp_P, exp_A, exp_B, exp_G_x, exp_G_y, exp_N;
@@ -860,13 +861,18 @@
     TEST_EQUAL( crv_tls_id->grp_id, id );
     TEST_EQUAL( crv_name->grp_id, id );
 
-    // Validate write_group against test data, read result
+    // Validate write_group against test data
     TEST_EQUAL( mbedtls_ecp_tls_write_group( &grp, &olen,
                                              buf, sizeof( buf ) ),
                 0 );
     TEST_EQUAL( mbedtls_test_hexcmp( buf, ecparameters, olen,
                                      sizeof( ecparameters ) ),
                 0 );
+
+    // Read group from buffer and compare with expected ID
+    TEST_EQUAL( mbedtls_ecp_tls_read_group_id( &read_g_id, &vbuf, olen ),
+                0 );
+    TEST_EQUAL( read_g_id, id );
     TEST_EQUAL( mbedtls_ecp_tls_read_group( &grp_read, &vbuf, olen ),
                 0 );
     TEST_EQUAL( grp_read.id, id );