tests: Get rid of mbedtls_test_unhexify() in unit test code

In test functions calling mbedtls_test_unhexify(), change the
type of the associated parameters from `char*` to `data_t`.

That way the `unhexify` operation is done by the test
framework and not by the unit test code.

Use for the new parameters of type data_t the name of the
local variable that used to store the `unhexify` version of
the `char*` parameter.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/suites/test_suite_chacha20.function b/tests/suites/test_suite_chacha20.function
index 137b92a..afe2418 100644
--- a/tests/suites/test_suite_chacha20.function
+++ b/tests/suites/test_suite_chacha20.function
@@ -8,63 +8,55 @@
  */
 
 /* BEGIN_CASE */
-void chacha20_crypt( char *hex_key_string,
-                     char *hex_nonce_string,
+void chacha20_crypt( data_t *key_str,
+                     data_t *nonce_str,
                      int counter,
-                     char *hex_src_string,
-                     char *hex_expected_output_string )
+                     data_t *src_str,
+                     data_t *expected_output_str )
 {
-    unsigned char key_str[32]; /* size set by the standard */
-    unsigned char nonce_str[12]; /* size set by the standard */
-    unsigned char src_str[375]; /* max size of binary input */
-    unsigned char expected_output_str[375];
     unsigned char output[375];
-    unsigned char output_string[751]; /* ASCII string representation of output */
-    size_t key_len;
-    size_t nonce_len;
-    size_t src_len;
-    size_t expected_output_len;
     mbedtls_chacha20_context ctx;
 
-    memset( key_str,       0x00, sizeof( key_str ) );
-    memset( nonce_str,     0x00, sizeof( nonce_str ) );
-    memset( src_str,       0x00, sizeof( src_str ) );
-    memset( output,        0x00, sizeof( output ) );
-    memset( output_string, 0x00, sizeof( output_string ) );
+    /*
+     * Buffers to store the ASCII string representation of output and
+     * expected_output_str.
+     */
+    unsigned char output_string[751] = { '\0' };
+    unsigned char expected_output_string[751] = { '\0' };
 
-    key_len   = mbedtls_test_unhexify( key_str, hex_key_string );
-    nonce_len = mbedtls_test_unhexify( nonce_str, hex_nonce_string );
-    src_len   = mbedtls_test_unhexify( src_str, hex_src_string );
-    expected_output_len = mbedtls_test_unhexify( expected_output_str,
-                                                 hex_expected_output_string );
+    memset( output, 0x00, sizeof( output ) );
 
-    TEST_ASSERT( src_len   == expected_output_len );
-    TEST_ASSERT( key_len   == 32U );
-    TEST_ASSERT( nonce_len == 12U );
+    TEST_ASSERT( src_str->len   == expected_output_str->len );
+    TEST_ASSERT( key_str->len   == 32U );
+    TEST_ASSERT( nonce_str->len == 12U );
 
     /*
      * Test the integrated API
      */
-    TEST_ASSERT( mbedtls_chacha20_crypt( key_str, nonce_str, counter, src_len, src_str, output ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_crypt( key_str->x, nonce_str->x, counter, src_str->len, src_str->x, output ) == 0 );
 
-    mbedtls_test_hexify( output_string, output, src_len );
-    TEST_ASSERT( strcmp( (char*) output_string, hex_expected_output_string ) == 0 );
+    mbedtls_test_hexify( expected_output_string,
+                         expected_output_str->x,
+                         expected_output_str->len);
+    mbedtls_test_hexify( output_string, output, src_str->len );
+    TEST_ASSERT( strcmp( (char *)output_string,
+                         (char *)expected_output_string ) == 0 );
 
     /*
      * Test the streaming API
      */
     mbedtls_chacha20_init( &ctx );
 
-    TEST_ASSERT( mbedtls_chacha20_setkey( &ctx, key_str ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_setkey( &ctx, key_str->x ) == 0 );
 
-    TEST_ASSERT( mbedtls_chacha20_starts( &ctx, nonce_str, counter ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_starts( &ctx, nonce_str->x, counter ) == 0 );
 
     memset( output, 0x00, sizeof( output ) );
-    TEST_ASSERT( mbedtls_chacha20_update( &ctx, src_len, src_str, output ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_update( &ctx, src_str->len, src_str->x, output ) == 0 );
 
-    mbedtls_test_hexify( output_string, output, src_len );
-    TEST_ASSERT( strcmp( (char*) output_string,
-                         hex_expected_output_string ) == 0 );
+    mbedtls_test_hexify( output_string, output, src_str->len );
+    TEST_ASSERT( strcmp( (char *)output_string,
+                         (char *)expected_output_string ) == 0 );
 
     /*
      * Test the streaming API again, piecewise
@@ -72,15 +64,16 @@
 
     /* Don't free/init the context nor set the key again,
      * in order to test that starts() does the right thing. */
-    TEST_ASSERT( mbedtls_chacha20_starts( &ctx, nonce_str, counter ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_starts( &ctx, nonce_str->x, counter ) == 0 );
 
     memset( output, 0x00, sizeof( output ) );
-    TEST_ASSERT( mbedtls_chacha20_update( &ctx, 1, src_str, output ) == 0 );
-    TEST_ASSERT( mbedtls_chacha20_update( &ctx, src_len - 1, src_str + 1, output + 1 ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_update( &ctx, 1, src_str->x, output ) == 0 );
+    TEST_ASSERT( mbedtls_chacha20_update( &ctx, src_str->len - 1,
+                                          src_str->x + 1, output + 1 ) == 0 );
 
-    mbedtls_test_hexify( output_string, output, src_len );
-    TEST_ASSERT( strcmp( (char*) output_string,
-                         hex_expected_output_string ) == 0 );
+    mbedtls_test_hexify( output_string, output, src_str->len );
+    TEST_ASSERT( strcmp( (char *)output_string,
+                         (char *)expected_output_string ) == 0 );
 
     mbedtls_chacha20_free( &ctx );
 }