Test suite covers enough values to execute all paths through code, but may not catch other errors triggered by special values.

Short-circuit evaluation (e.g., if(a && b || do_something()) {…} ).
Covering all paths through the lines of code may not cover all paths through the expressions contained within.

On exam 2:  insert_into_bst(…), our test on that question had 100% line coverage but not path coverage.

float calculate_inverse(float n) {
    return 1.0 / n;  // what if n == 0?
}