diff --git a/tests/io_dset_sparse_text.c b/tests/io_dset_sparse_text.c
index ee33e68..1d28813 100644
--- a/tests/io_dset_sparse_text.c
+++ b/tests/io_dset_sparse_text.c
@@ -1,25 +1,37 @@
-#include <stdint.h>
-#include <stdlib.h>
-#include <stdio.h>
 #include "trexio.h"
 #include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
 
-#define FILENAME "test_sparse.dir"
+#define TEST_BACKEND 	TREXIO_TEXT
+#define TREXIO_FILE 	"test_dset_sparse.dir"
+#define RM_COMMAND 	  "rm -rf " TREXIO_FILE
+#define SIZE          100
+#define N_CHUNKS      5
 
+static int test_write_dset_sparse (const char* file_name, const back_end_t backend) {
 
-int main(){
+/* Try to write an array of sparse data into the TREXIO file */
 
-  uint64_t offset_f = 0;
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
 
-  // create the data to write
-  uint64_t size = 100;
+/*================= START OF TEST ==================*/
+
+  // open file in 'write' mode
+  file = trexio_open(file_name, 'w', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // parameters to be written
   int32_t* index;
   double* value;
 
-  index = calloc(4L*size, sizeof(int32_t));
-  value = calloc(size, sizeof(double));
+  index = calloc(4L*SIZE, sizeof(int32_t));
+  value = calloc(SIZE, sizeof(double));
 
-  for(int i=0; i<size; i++){
+  for(int i=0; i<SIZE; i++){
     index[4*i]   = 4*i;
     index[4*i+1] = 4*i+1;
     index[4*i+2] = 4*i+2;
@@ -27,86 +39,163 @@ int main(){
     value[i]     = 3.14 + (double) i;
   }
 
-  int rc_open;
-  trexio_t* trexio_file = trexio_open(FILENAME, 'w', TREXIO_TEXT, &rc_open);
-  assert(rc_open == TREXIO_SUCCESS);
-  assert(trexio_file != NULL);
+  // write dataset chunks of sparse data in the file (including FAKE statements)
+  uint64_t chunk_size = (uint64_t) SIZE/N_CHUNKS;
+  uint64_t offset_f = 0;
 
-
-  // check if the file exists
-  int rc;
-  rc = trexio_has_mo_2e_int_eri(trexio_file);
-  assert(rc==TREXIO_SUCCESS || rc==TREXIO_HAS_NOT);
-
-  if(rc==TREXIO_HAS_NOT){
-    printf("FILE DID NOT EXIST AT THE START.\n");
-  } else {
-    printf("FILE EXIST AT THE START.\n");
-  }
-
-  // check that previous call to has_sparse did not create a file
-  if (rc==TREXIO_HAS_NOT) {
-    rc = trexio_has_mo_2e_int_eri(trexio_file);
-    assert(rc==TREXIO_HAS_NOT);
-  }
-
-  // define chunks: here they contain 20 elements, i.e. 100/5
-  int n_chunks = 5;
-  uint64_t chunk_size = size/n_chunks;
-
-  // write 5 chunks using write_sparse
-  for(int i=0; i<n_chunks; ++i){
-    rc = trexio_write_mo_2e_int_eri(trexio_file, offset_f, chunk_size, &index[4*offset_f], &value[offset_f]);
-    assert(rc==TREXIO_SUCCESS);
+  // write n_chunks times using write_sparse
+  for(int i=0; i<N_CHUNKS; ++i){
+    rc = trexio_write_mo_2e_int_eri(file, offset_f, chunk_size, &index[4*offset_f], &value[offset_f]);
+    assert(rc == TREXIO_SUCCESS);
     offset_f += chunk_size;
   }
 
-  rc = trexio_close(trexio_file);
-  assert(rc == TREXIO_SUCCESS);
-  // TODO: SHOULD NOT TREXIO_CLOSE SET TO NULL THE TREXIO_T POINTER ???
-  //assert(trexio_file == NULL);
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
 
-  trexio_t* trexio_file_2 = trexio_open(FILENAME, 'r', TREXIO_TEXT, &rc_open);
-  assert(rc_open == TREXIO_SUCCESS);
-  assert(trexio_file_2 != NULL);
-
-  // define arrays to read into
-  int32_t* index_read;
-  double* value_read;
-
-  index_read = (int32_t*) calloc(4L*chunk_size,sizeof(int32_t));
-  value_read = (double*) calloc(chunk_size,sizeof(double));
-
-  // read 1 chunk of 20 elements using offset of 40( i.e. lines No. 40--59)
-  uint64_t offset_f_read = 40L;
-  int offset_data_read = 5;
-  rc = trexio_read_mo_2e_int_eri(trexio_file_2, offset_f_read, 10L, &index_read[4*offset_data_read], &value_read[offset_data_read]);
-  assert(rc==TREXIO_SUCCESS);
-  assert(index_read[0]==0 && index_read[4*offset_data_read]==offset_f_read*4);
-
-  // print the data being read
-  for(int i=0; i<chunk_size; ++i){
-    printf("%d %d %d %d %lf\n",
-    index_read[4*i],
-    index_read[4*i+1],
-    index_read[4*i+2],
-    index_read[4*i+3],
-    value_read[i]
-    );
-  }
-
-  // check that the file has been created
-  rc = trexio_has_mo_2e_int_eri(trexio_file_2);
-  assert(rc==TREXIO_SUCCESS);
-
-  // close the TREXIO file
-  rc = trexio_close(trexio_file_2);
-  assert(rc == TREXIO_SUCCESS);
-
-  // free the memory
+  // free the allocated memeory
   free(index);
   free(value);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_has_dset_sparse (const char* file_name, const back_end_t backend) {
+
+/* Try to check the existence of a dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // first check that mo_2e_int_eri_lr (we only write non-lr component in this unit test)
+  rc = trexio_has_mo_2e_int_eri_lr(file);
+  assert(rc==TREXIO_HAS_NOT);
+
+  // check that previous call to has_sparse did not create a file/dset
+  rc = trexio_has_mo_2e_int_eri_lr(file);
+  assert(rc==TREXIO_HAS_NOT);
+
+  // now check that previously written mo_2e_int_eri exists
+  rc = trexio_has_mo_2e_int_eri(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_read_dset_sparse (const char* file_name, const back_end_t backend) {
+
+/* Try to read one chunk of dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+ // define arrays to read into
+  int32_t* index_read;
+  double* value_read;
+  uint64_t size = 20L;
+
+  index_read = (int32_t*) calloc(4L*size,sizeof(int32_t));
+  value_read = (double*) calloc(size,sizeof(double));
+
+  // specify the read parameters, here:
+  // 1 chunk of 10 elements using offset of 40 (i.e. lines No. 40--59) into elements of the array starting from 5
+  uint64_t chunk_read = 10L;
+  uint64_t offset_file_read = 40L;
+  int offset_data_read = 5;
+
+  // read one chunk using the aforementioned parameters
+  rc = trexio_read_mo_2e_int_eri(file, offset_file_read, chunk_read, &index_read[4*offset_data_read], &value_read[offset_data_read]);
+  assert(rc == TREXIO_SUCCESS);
+  assert(index_read[0] == 0);
+  assert(index_read[4*offset_data_read] == offset_file_read*4);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+  // free the memory
   free(index_read);
   free(value_read);
 
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_read_dset_sparse_size (const char* file_name, const back_end_t backend, const int64_t size_check) {
+
+/* Try to read a size of the dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // define the variable to read into
+  int64_t size_written;
+
+  // read one chunk using the aforementioned parameters
+  rc = trexio_read_mo_2e_int_eri_size(file, &size_written);
+  assert(rc == TREXIO_SUCCESS);
+  assert(size_written == size_check);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+int main(){
+
+/*============== Test launcher ================*/
+
+  int rc;
+  rc = system(RM_COMMAND);
+  assert (rc == 0);
+
+  // check the first write attempt (SIZE elements written in N_CHUNKS chunks)
+  test_write_dset_sparse    (TREXIO_FILE, TEST_BACKEND);
+  test_has_dset_sparse      (TREXIO_FILE, TEST_BACKEND);
+  test_read_dset_sparse     (TREXIO_FILE, TEST_BACKEND);
+  test_read_dset_sparse_size(TREXIO_FILE, TEST_BACKEND, (int64_t) SIZE);
+
+  // check the second write attempt (SIZE elements written in N_CHUNKS chunks)
+  test_write_dset_sparse    (TREXIO_FILE, TEST_BACKEND);
+  test_read_dset_sparse_size(TREXIO_FILE, TEST_BACKEND, (int64_t) SIZE*2);
+
+  rc = system(RM_COMMAND);
+  assert (rc == 0);
+
+  return 0;
 }