Introduce mbed-crypto tests

Add tests setup code and random bytes generator test.

TESTS/mbed-crypto/sanity/main.cpp

@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include "mbed.h"
+#include "greentea-client/test_env.h"
+#include "unity.h"
+#include "utest.h"
+#include "psa/crypto.h"
+
+using namespace utest::v1;
+
+void test_crypto_random(void)
+{
+    static const unsigned char trail[] = "don't overwrite me";
+    unsigned char changed[256] = { 0 };
+    unsigned char output[sizeof(changed) + sizeof(trail)];
+    size_t i, bytes = sizeof(changed);
+    unsigned int run;
+
+    TEST_ASSERT_EQUAL(PSA_SUCCESS, psa_crypto_init());
+
+    memcpy(output + bytes, trail, sizeof(trail));
+    /* Run several times, to ensure that every output byte will be
+     * nonzero at least once with overwhelming probability
+     * (2^(-8*number_of_runs)). */
+    for (run = 0; run < 10; run++) {
+        memset(output, 0, bytes);
+        TEST_ASSERT_EQUAL(PSA_SUCCESS, psa_generate_random(output, bytes));
+        /* Check that no more than 'bytes' have been overwritten */
+        TEST_ASSERT_EQUAL_UINT8_ARRAY(trail, output + bytes, sizeof(trail));
+
+        for (i = 0; i < bytes; i++) {
+            if (0 != output[i]) {
+                ++changed[i];
+            }
+        }
+    }
+
+    /* Check that every byte was changed to nonzero at least once. This
+     * validates that psa_generate_random is overwriting every byte of
+     * the output buffer. */
+    for (i = 0; i < bytes; i++) {
+        TEST_ASSERT_NOT_EQUAL(0, changed[i]);
+    }
+
+    mbedtls_psa_crypto_free();
+}
+
+utest::v1::status_t case_failure_handler(const Case *const source, const failure_t reason)
+{
+    mbedtls_psa_crypto_free();
+    greentea_case_failure_abort_handler(source, reason);
+    return STATUS_CONTINUE;
+}
+
+utest::v1::status_t test_setup(const size_t number_of_cases)
+{
+    GREENTEA_SETUP(120, "default_auto");
+    return verbose_test_setup_handler(number_of_cases);
+}
+
+Case cases[] = {
+    Case("mbed-crypto random", test_crypto_random, case_failure_handler),
+};
+
+Specification specification(test_setup, cases);
+
+int main(void)
+{
+    return !Harness::run(specification);
+}