Testing

Pre- and Post-Conditions

1. Review the MyroC.h header file documentation.
1. In the documentation, find at least two functions that have stated a "pre-condition" and at least two functions that have stated a "post-condition". (Note that every function should have postconditions, otherwise there would be not point in calling it.)
2. In anticipation of later work in this lab, review the documentation for the function rMotors. The documentation does not explicitly state pre-conditions for this function, but one might infer such conditions. Write a careful statement of the implied pre-condition(s) for rMotors.
2. The program motors-test.c sets the motor speeds of the Scribbler to the given leftspeed and rightspeed.
   1. Initialize the variables leftspeed and rightspeed to 1.
   2. Initialize the variables leftspeed and rightspeed to 1 and -1 respectively.
   3. Initialize the variables leftspeed and rightspeed to 2 and -1. respectively.
   4. Now try 6 and 5 respectively.
   5. Try other numbers that you might need to figure out what works and what doesn't.
   6. How do these experimental results compare with the pre-conditions that you inferred in Step 1b?

The assert Function in C

3. Modify the same code, motors-test.c, to use assert so that it will test the precondition(s) you wrote for rMotors in motors-test.c.

Note: You can read about C's assert function in the accompanying reading and/or using the command man assert in a terminal window. Better yet, read about assert in both places!

Choosing Test Cases

4. Copy the program object-avoid.c to your working directory. This program attempts to control the robot in avoiding obstacles. Run the program a few times and observe what it does.
   1. Develop two test plans for object-avoid.c to figure out if the program works correctly. That is, apply both black-box and white box testing by identifying test cases that will cover a full range of situations that might be encountered in executing the program object-avoid.c . Remember that:
      • Black-box testing is when the problem is examined to determine the logical cases that might arise. Test cases are developed without reference to details of code.
      • White-box testing is when the code is examined to determine each of the possible conditions that may arise, and tests are developed to exercise each part of the code.
   2. You should have found that the program is not working properly. Now fix the program so that it performs in the intended way and the robot avoids obstacles.
5. Program follower-test.c is supposed to control the robot in following a sheet of paper which is held in front of the robot.
   1. Develop two test plans for this program, using both black-box and white-box testing strategies. Apply both black-box and white box testing to identify tests cases that will cover a full range of situations that might be encountered.
   2. Run follower-test.c  with all the cases from your test plan to determine whether the program works correctly.
   3. Fix the errors you found in the program.
   4. Run the program again with all the cases from your test plan to be sure that it now works correctly.