Test Cases for Marks (0 to 100): BVA and Equivalence Class Testing

Valid range: 0 <= marks <= 100 (integers). Anything else must be rejected with an error message.

1. Boundary Value Analysis (BVA)

Test at and around each boundary (min-1, min, min+1, nominal, max-1, max, max+1):

TC	Input	Expected output
B1	-1	Invalid (just below minimum)
B2	0	Valid (minimum)
B3	1	Valid (just above minimum)
B4	50	Valid (nominal)
B5	99	Valid (just below maximum)
B6	100	Valid (maximum)
B7	101	Invalid (just above maximum)

Total = 7 test cases (robust BVA). Standard BVA without the two invalid values has 5.

2. Equivalence Class Testing (ECT)

Divide the input domain into classes whose members behave alike; test one value per class.

Class	Range	Type	Representative input	Expected output
EC1	marks < 0	Invalid	-20	Error
EC2	0 to 100	Valid	55	Accepted
EC3	marks > 100	Invalid	150	Error

Non-integer or non-numeric input (e.g. "abc") can be added as a further invalid class.

Total = 3 test cases (4 with the non-numeric class).

3. Comparison of the test sets

Basis	BVA	Equivalence class testing
Number of tests	7	3
Focus	Edges of ranges, where off-by-one errors occur (e.g. < written instead of <=)	Whole classes of input, one representative each
Defect finding	Strong for boundary errors	Strong for general class errors, weak at boundaries
Redundancy	Higher	Minimal

Example: if the code wrongly checks marks < 100, ECT value 55 passes but BVA input 100 exposes the bug.

Conclusion

ECT reduces the number of tests; BVA finds boundary defects. Using them together (for example 3 + the boundary values) gives better coverage with a small test set.