Expected vs actual

301.13 Testing

Testing — Note 4 of 6

Compare predicted output.

What you need to know

Before running a test, predict the expected output. Then run the program and compare with the actual output. If they differ, there is a bug to investigate.

What to know

Expected: what the output should be based on the spec
Actual: what the program really outputs
Match = test passed, mismatch = bug found
Record both in a test table for documentation

Code examples

Expected vs actual

python

# Test: input 15 into age checker (pass mark >=18)
# Expected output: "Minor"
# Actual output: "Minor" ✓ PASS

# Test: input 18
# Expected: "Adult"
# Actual: "Minor" ✗ FAIL — bug in condition

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Specification notes for programming are in Paper 2.

Expected vs actual

301.13 Testing

Practise exam questions

Testing — Note 4 of 6

Compare predicted output.

What you need to know

Before running a test, predict the expected output. Then run the program and compare with the actual output. If they differ, there is a bug to investigate.

What to know

Expected: what the output should be based on the spec
Actual: what the program really outputs
Match = test passed, mismatch = bug found
Record both in a test table for documentation

Code examples

Expected vs actual

python

# Test: input 15 into age checker (pass mark >=18)
# Expected output: "Minor"
# Actual output: "Minor" ✓ PASS

# Test: input 18
# Expected: "Adult"
# Actual: "Minor" ✗ FAIL — bug in condition

← Previous noteDry run tracing301.13 Testing Next note →Test tables301.13 Testing

Back to Testing

Specification notes for programming are in Paper 2.