Testing and Debugging Conditionals

Computer Science Department

bernstdh@jmu.edu

Review

Desk Checking:
- Verifying that a program satisfies specifications by carefully reading the code
Testing:
- Verifying that a program satisfies specifications by executing the code
Debugging:
- Locating and repairing logic errors

Desk Checking Conditionals

Conditions Involving Equality:
- Check for the use of = instead of ==
- Check for the use of == instead of .equals() with reference types
- Check for the use of == with floating point numbers
Conditions Involving Inequality:
- Check for directionality mistakes
- Check for weak inequalities in the place of strict inequalities

Testing Conditionals

The Sets Involved:
- A discrete set of elements
- A continuous range/interval of elements
The Condition(s):
- Single
- Compound
- Nested

Testing Conditionals Involving Discrete Sets

Possible Errors:
- An error involving one or more elements of the set
- An error that involves non-elements
Test Cases to Include:
- Each member of the set
- A value smaller than the smallest member
- A value larger than the largest member
- A value between two members

Testing Conditionals Involving Discrete Sets (cont.)

An Example:

if (seatLocationCode == 100) { // ... } else if (seatLocationCode == 200) { // ... } else if (seatLocationCode == 300) { // ... } else { // ... }

Test cases: 50 100 150 200 300 1000

Testing Conditionals Involving Intervals/Ranges

Possible Errors:
- An error involving one or more elements of the set
- An error that involves a boundary of the set (whether the interval is open or closed)
- An error that involves non-elements
Test Cases to Include:
- Several elements in the interval
- A value smaller than the lower bound
- A value larger than the upper bound
- The lower bound
- The upper bound

Testing Conditionals Involving Intervals/Ranges (cont.)

An Example:

if ((income > 0.0) && (income < 20000.0)) { // ... } else { // ... }

Test cases: -1.0 0.0 10000.0 20000.0 20001.0

Testing Compound and Nested Conditions

Compound/Nested Conditions (cont.)

An Example of a Compound Condition:

if ((height >= 62) && (sex == 'M')) { // ... }

Test cases:
70, 'M'
70, 'F'
62, 'M'
62, 'F'
50, 'M'
50, 'F'

Testing Compound/Nested Conditions (cont.)

An Example of Nested Conditions:

if (height >= 62) { if (sex == 'M') { // ... } else { // ... } } else { if (sex == 'M') { // ... } else { // ... } }

Test cases:
70, 'M'
70, 'F'
62, 'M'
62, 'F'
50, 'M'
50, 'F'

Instrumenting Conditionals During Debugging

The Basics:
- Include print() calls before, inside, and after the conditional statements
- Include print() calls that check for "accidental assignments" (i.e., use of the = operator instead of the == operator)
A Warning:
- You may need to reorganize your code (e.g., use intermediate variables) in order to print some values

An Example of Instrumenting Conditionals

javaexamples/basics/DebuggingConditionals.java (Fragment: 0)

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