Boundary test data

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Boundary test data

Name:
Date:
Class:
A

Quick Questions

Shade in the A or B circle for each question.

1. An age field accepts whole numbers from 0 to 120. Which set is boundary test data for this range?
A -1, 0, 120, 121
B 0, 60, 120, 200
2. For the range 0 to 120, which pair of values tests the bottom limit?
A 0 and -1
B 0 and 1
3. For the range 0 to 120, which pair of values tests the top limit?
A 119 and 120
B 120 and 121
4. Why do we test 121 as well as 120 for a range of 0 to 120?
A To check the program accepts every value above 120
B To check the program rejects the nearest invalid value above the limit
5. A programmer wrongly codes the check as age < 120 instead of age <= 120. Which boundary test would show the error?
A Entering 120, which should be accepted but is rejected
B Entering 60, which should be accepted and is accepted
B

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left columnRight column
10 and -1 AThese values are far outside the range. Boundary data uses the values right next to the limits, -1 and 121, along with 0 and 120.
2120 and 121 BTest 120 (accept) and 121 (reject)
3Boundary data checks that the upper limit is coded correctly, so a test needs a pair of values either side of it CThe boundary pair at the top of a range 0 to 120: the largest accepted value and the nearest rejected value above it
4Boundary data checks that the lower limit is coded correctly, such as catching a program that wrongly uses > 0 instead of >= 0 DThese are only accepted values and no rejected values are included. Boundary data needs the nearest rejected values too, -1 and 121.
5Boundary test data for 0 to 120: 0, 60, 120 ETest 0 (accept) and -1 (reject)
6Boundary test data for 0 to 120: -50, 200 FThe boundary pair at the bottom of a range 0 to 120: the smallest accepted value and the nearest rejected value below it
C

Definitions

Boundary test data
D

Fill in the Blanks

Complete each line of code by filling in the missing parts.

1.
// Range 0 to 120: smallest accepted value TestAge ← _
2.
// Range 0 to 120: nearest rejected below TestAge ← __
3.
// Range 0 to 120: largest accepted value TestAge ← ___
4.
// Range 0 to 120: nearest rejected above TestAge ← ___
5.
IF TestAge >= 0 AND TestAge __ 120 THEN OUTPUT "Accepted" ENDIF
E

Spot the Error

Shade in the letter of the line that contains an error.

Question 1
A // Range check 0 to 120
B Accept: 1 and 119
C Reject: -1 and 121
Question 2
A // Test the bottom limit
B Accepted boundary: 0
C Rejected boundary: 1
Question 3
A // Test the top limit
B Accepted boundary: 119
C Rejected boundary: 121
Question 4
A REPEAT
B INPUT Age
C UNTIL Age >= 0 AND Age < 120
D OUTPUT Age
Question 5
A Each limit needs one value
B One is accepted at the limit
C One is rejected just beyond

Answer Key

Boundary test data
Section A: Quick Questions
Q1
A — -1, 0, 120, 121
Q2
A — 0 and -1
Q3
B — 120 and 121
Q4
B — To check the program rejects the nearest invalid value above the limit
Q5
A — Entering 120, which should be accepted but is rejected
Section B: Match the Pairs
Q1
0 and -1 → The boundary pair at the bottom of a range 0 to 120: the smallest accepted value and the nearest rejected value below it
Q2
120 and 121 → The boundary pair at the top of a range 0 to 120: the largest accepted value and the nearest rejected value above it
Q3
Boundary data checks that the upper limit is coded correctly, so a test needs a pair of values either side of it → Test 120 (accept) and 121 (reject)
Q4
Boundary data checks that the lower limit is coded correctly, such as catching a program that wrongly uses > 0 instead of >= 0 → Test 0 (accept) and -1 (reject)
Q5
Boundary test data for 0 to 120: 0, 60, 120 → These are only accepted values and no rejected values are included. Boundary data needs the nearest rejected values too, -1 and 121.
Q6
Boundary test data for 0 to 120: -50, 200 → These values are far outside the range. Boundary data uses the values right next to the limits, -1 and 121, along with 0 and 120.
Section C: Definitions
Q1
Boundary test data — The largest and smallest acceptable values plus the nearest rejected values either side of each limit, e.g. 0 and -1, 120 and 121 for a range of 0 to 120.
Section D: Fill in the Blanks
Q1
// Range 0 to 120: smallest accepted value TestAge ← 0
Q2
// Range 0 to 120: nearest rejected below TestAge ← -1
Q3
// Range 0 to 120: largest accepted value TestAge ← 120
Q4
// Range 0 to 120: nearest rejected above TestAge ← 121
Q5
IF TestAge >= 0 AND TestAge <= 120 THEN OUTPUT "Accepted" ENDIF
Section E: Spot the Error
Q1
B — The boundary values accepted are the smallest and largest valid values, 0 and 120. 1 and 119 are inside the range, not on its limits.
Q2
C — 1 is inside the range 0 to 120, so it is accepted. The rejected boundary value just below the bottom limit is -1.
Q3
B — The accepted boundary at the top is the largest valid value, 120. 119 is valid but it is not on the limit.
Q4
C — With < the valid boundary value 120 would be rejected. The test 120 would expose this. The condition should use <= 120.
Q5
A — Boundary data uses a pair at each limit: the accepted value on the limit and the nearest rejected value beyond it. One value cannot show where the limit is.