tried to improve the documentation of the function utils_removeChars + made it more defensive + fixed the testcases

src/shellmatta_utils.c

@@ -215,13 +215,14 @@ void utils_insertChars( shellmatta_instance_t   *inst,
  *              position
  * @param[in]   inst        pointer to a shellmatta instance
  * @param[in]   length      number of characters to remove
- * @param[in]   backspace   remove characters left of the cursor
+ * @param[in]   backspace   true    ==> remove characters left of the cursor
+ *                          false   ==> remove characters right of the cursor
  */
 void utils_removeChars( shellmatta_instance_t   *inst,
                         uint32_t                 length,
                         bool                     backspace)
 {
-    if(0u != length)
+    if((0u != length) && (inst->inputCount >= inst->cursor))
     {
         /** -# rewind the cursor in case of backspace */
         if(true == backspace)

test/unittest/shellmatta_utils/test_utils_removeChars.cpp

@@ -141,8 +141,8 @@ TEST_CASE("shellmatta_utils_removeChars_remove_chars_in_the_middle_of_the_buffer
     utils_removeChars(&inst, length, backspace);
 
     CHECK( inst.cursor == 10u);
-    CHECK( inst.inputCount == 20u);
-    REQUIRE(strncmp("abcdefghijklmnopqr", buffer, sizeof(buffer)) == 0);
+    CHECK( inst.inputCount == 15u);
+    REQUIRE(strncmp("abcdefghijpqr", buffer, sizeof(buffer)) == 0);
 }
 
 TEST_CASE("shellmatta_utils_removeChars_remove_more_chars_in_middle_of_buffer_than_are_present_backspace_false"){
@@ -168,8 +168,8 @@ TEST_CASE("shellmatta_utils_removeChars_remove_more_chars_in_middle_of_buffer_th
     utils_removeChars(&inst, length, backspace);
     
     CHECK( inst.cursor == 10u);
-    CHECK( inst.inputCount == 20u);
-    REQUIRE(strncmp("abcdefghijklmnopqr", buffer, sizeof(buffer)) == 0);
+    CHECK( inst.inputCount == 10u);
+    REQUIRE(strncmp("abcdefghij", buffer, 10u) == 0);
 }
 
 TEST_CASE("shellmatta_utils_removeChars_curser_outside_buffer"){