New macros TEST_EQUAL, ASSERT_ALLOC, ASSERT_ALLOC_WEAK

Backports some test helper macros added after 2.16. This will facilitate
backporting new test code.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/suites/helpers.function

@@ -160,6 +160,66 @@ typedef enum
        }                                                    \
     } while( 0 )
 
+/** Evaluate two expressions and fail the test case if they have different
+ * values.
+ *
+ * \param expr1     An expression to evaluate.
+ * \param expr2     The expected value of \p expr1. This can be any
+ *                  expression, but it is typically a constant.
+ */
+#define TEST_EQUAL( expr1, expr2 )              \
+    TEST_ASSERT( ( expr1 ) == ( expr2 ) )
+
+/** Allocate memory dynamically and fail the test case if this fails.
+ * The allocated memory will be filled with zeros.
+ *
+ * You must set \p pointer to \c NULL before calling this macro and
+ * put `mbedtls_free( pointer )` in the test's cleanup code.
+ *
+ * If \p length is zero, the resulting \p pointer will be \c NULL.
+ * This is usually what we want in tests since API functions are
+ * supposed to accept null pointers when a buffer size is zero.
+ *
+ * This macro expands to an instruction, not an expression.
+ * It may jump to the \c exit label.
+ *
+ * \param pointer   An lvalue where the address of the allocated buffer
+ *                  will be stored.
+ *                  This expression may be evaluated multiple times.
+ * \param length    Number of elements to allocate.
+ *                  This expression may be evaluated multiple times.
+ *
+ */
+#define ASSERT_ALLOC( pointer, length )                           \
+    do                                                            \
+    {                                                             \
+        TEST_ASSERT( ( pointer ) == NULL );                       \
+        if( ( length ) != 0 )                                     \
+        {                                                         \
+            ( pointer ) = mbedtls_calloc( sizeof( *( pointer ) ), \
+                                          ( length ) );           \
+            TEST_ASSERT( ( pointer ) != NULL );                   \
+        }                                                         \
+    }                                                             \
+    while( 0 )
+
+/** Allocate memory dynamically. If the allocation fails, skip the test case.
+ *
+ * This macro behaves like #ASSERT_ALLOC, except that if the allocation
+ * fails, it marks the test as skipped rather than failed.
+ */
+#define ASSERT_ALLOC_WEAK( pointer, length )                      \
+    do                                                            \
+    {                                                             \
+        TEST_ASSERT( ( pointer ) == NULL );                       \
+        if( ( length ) != 0 )                                     \
+        {                                                         \
+            ( pointer ) = mbedtls_calloc( sizeof( *( pointer ) ), \
+                                          ( length ) );           \
+            TEST_ASSUME( ( pointer ) != NULL );                   \
+        }                                                         \
+    }                                                             \
+    while( 0 )
 /** Compare two buffers and fail the test case if they differ.
  *
  * This macro expands to an instruction, not an expression.