MPS Reader Tests: Add test for >1 feed-get-commit-reclaim cycles

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/tests/suites/test_suite_mps.data b/tests/suites/test_suite_mps.data
index ba89582..41e0052 100644
--- a/tests/suites/test_suite_mps.data
+++ b/tests/suites/test_suite_mps.data
@@ -3,3 +3,9 @@
 
 MPS Reader: Single step, single round, pausing enabled but unused
 mbedtls_mps_reader_no_pausing_single_step_single_round:1
+
+MPS Reader: Single step, multiple rounds, pausing disabled
+mbedtls_mps_reader_no_pausing_single_step_multiple_rounds:0
+
+MPS Reader: Single step, multiple rounds, pausing enabled but unused
+mbedtls_mps_reader_no_pausing_single_step_multiple_rounds:1
diff --git a/tests/suites/test_suite_mps.function b/tests/suites/test_suite_mps.function
index 9b06c9c..f291974 100644
--- a/tests/suites/test_suite_mps.function
+++ b/tests/suites/test_suite_mps.function
@@ -60,3 +60,54 @@
     mbedtls_reader_free( &rd );
 }
 /* END_CASE */
+
+/* BEGIN_CASE depends_on:TEST_SUITE_MPS_READER */
+void mbedtls_mps_reader_no_pausing_single_step_multiple_rounds( int with_acc )
+{
+    /* This test exercises multiple rounds o fthe basic use of the MPS reader:
+     * - The 'producing' layer provides a buffer
+     * - The 'consuming' layer fetches it in a single go.
+     * - After processing, the consuming layer commit the data
+     *   and returns back to the producing layer.
+     *
+     * Parameters:
+     * - with_acc: 0 if the reader should be initialized without accumulator.
+     *             1 if the reader should be initialized with accumulator.
+     *
+     *             Whether the accumulator is present or not should not matter,
+     *             since the consumer's request can be fulfilled from the data
+     *             that the producer has provided.
+     */
+
+    unsigned char bufA[100], bufB[100];
+    unsigned char acc[10];
+    unsigned char *tmp;
+    mbedtls_reader rd;
+    for( int i=0; (unsigned) i < sizeof( bufA ); i++ )
+        bufA[i] = (unsigned char) i;
+    for( int i=0; (unsigned) i < sizeof( bufB ); i++ )
+        bufB[i] = ~ ((unsigned char) i);
+
+    /* Preparation (lower layer) */
+    if( with_acc == 0 )
+        mbedtls_reader_init( &rd, NULL, 0 );
+    else
+        mbedtls_reader_init( &rd, acc, sizeof( acc ) );
+    TEST_ASSERT( mbedtls_reader_feed( &rd, bufA, sizeof( bufA ) ) == 0 );
+    /* Consumption (upper layer) */
+    /* Consume exactly what's available */
+    TEST_ASSERT( mbedtls_reader_get( &rd, 100, &tmp, NULL ) == 0 );
+    ASSERT_COMPARE( tmp, 100, bufA, 100 );
+    TEST_ASSERT( mbedtls_reader_commit( &rd ) == 0 );
+    /* Preparation */
+    TEST_ASSERT( mbedtls_reader_reclaim( &rd, NULL ) == 0 );
+    TEST_ASSERT( mbedtls_reader_feed( &rd, bufB, sizeof( bufB ) ) == 0 );
+    /* Consumption */
+    TEST_ASSERT( mbedtls_reader_get( &rd, 100, &tmp, NULL ) == 0 );
+    ASSERT_COMPARE( tmp, 100, bufB, 100 );
+    TEST_ASSERT( mbedtls_reader_commit( &rd ) == 0 );
+    /* Wrapup (lower layer) */
+    TEST_ASSERT( mbedtls_reader_reclaim( &rd, NULL ) == 0 );
+    mbedtls_reader_free( &rd );
+}
+/* END_CASE */