Home >> Glass Box Testing

Contents

• Definition
• Statement Coverage
• Branch Coverage
• Condition Coverage
• Path Coverage

The testing of software based on the internal logic of a module/system. Glass Box Testing operates in both inspection and demonstration mode (debug feature).

Tests such that every statement is executed at least once.

Advantages:
• Easy to design
• Easy to communicate
Disadvantages:
• Does no exercise all conditions
• Inflection points produce accurate anomolies.

This is a reasonable minimum test.

Example: Insert a number Y into a descending sorted array X of N values.

Test Case #1: X={6,4,2}, Y=1		Test Case #2: X={6,4,2}, Y=7
Click to enlarge		Click to enlarge

Tests such that each branch of code executes at least once (or every decision gets at least one T and at least one F).

Advantage:
• Easy to design
Disadvantage:
• Does not excercise all conditions

Using 85% of the branches usually produces acceptable results.

Tests such that every combination of conditions is executed.

Advantage:
• Logical
Disadvantages:
• Inflection points of produce ambiguity
• Number of cases explodes

Example: Insert a number Y into a descending sorted array X of N values.

Test Case #3: X={4}, Y=3
Click to enlarge

Tests such that every execution path is travelled.

Advantage:
• Logical and Complete
Disadvantage:
• Many test cases

Example: Insert a number Y into a descending sorted array X of N values.

Test Case #4: X={}, Y=5
Click to enlarge

This is approximately 10 fold more analysis and cases than Branch Coverage. This is imparative for medical and other critical components.