chore: add comments, rename test

Author: Fumuran

miden-tx/src/tests/kernel_tests/test_tx.rs

@@ -656,6 +656,7 @@ fn test_check_get_item_index() {
     assert_eq!(expected_root, result_root);
 }
 
+/// Check the memory layout after different invocations of the foreign procedure
 #[test]
 fn test_fpi_memory() {
     // Prepare the test data
@@ -813,15 +814,26 @@ fn test_fpi_memory() {
 
     let process = tx_context.execute_code(&code).unwrap();
 
+    // Check that the second invocation of the foreign procedure from the same account does not load
+    // the account data again: already loaded data should be reused.
+    //
+    // Native account:    [2048; 4095] <- initialized during prologue
+    // Foreign account:   [4096; 6143] <- initialized during first FPI
+    // Next account slot: [6144; 8191] <- should not be initialized
     assert_eq!(
         try_read_root_mem_value(&process, NATIVE_ACCOUNT_DATA_PTR + ACCOUNT_DATA_LENGTH as u32 * 2),
         None,
         "Memory starting from 6144 should stay uninitialized"
     );
 }
 
+/// Test the correctness of the foreign procedure execution.
+///
+/// It checks the foreign account code loading, providing the mast forest to the executor,
+/// construction of the account procedure maps and execution the foreign procedure in order to
+/// obtain the data from the foreign account's storage slot.
 #[test]
-fn test_fpi_basic() {
+fn test_fpi_execute_foreign_procedure() {
     let foreign_account_code_source = "
         use.miden::account