INTEGRATION TESTING

1
INTEGRATION TESTING

• After or during Unit Testing
• Putting modules together in a controlled way to
  incrementally build up the final system.
• Start with a hierarchy of modules.
• Write Stubs and Drivers as needed.

2
HIERARCHY
A

C
D
B
F
E
G
COPY DOWN
3
BOTTOM-UP

Test B,E,F
Test E
Test A,B,C,D, E,F,G
Test F
Test C
Test D,G
Test G
4
Bottom-Up Testing

• No need for Stubs.
• Useful when many of the low-level components are
  general-purpose utility routines that are invoked
  often by others.
• Useful for object-oriented design.
• Major system functionality tested last!

5
TOP-DOWN

Test A,B,C,D, E,F,G
Test A,B,C,D
Test A
6
Top-Down Design

• No need for Drivers.
• Test main functionality early.
• More stubs than drivers.
• Stubs are usually harder to write.
• May find some timing problems (low level modules)
  late in the testing cycle.

7
Modified Top-Down

Test
Test
B
E
Test
Test
Test
Test
Test
A,B,C,D
A,B,C, D,E,F
A
C
F
Test
Test
D
G
8
Modified Top-Down

• Reduces the number of stubs.
• Some drivers are needed to test each module
  separately.

9
BIG-BANG
Test
A
Test

B
Test
C
Test
Test
A,B,C,D,E,F,G
D
Test
E
Test
Test
F
G
10
BIG BANG

• Most programmers use this method.
• Somewhat practical for small systems.
• Not practical for large systems.
• Requires both stubs and drivers.
• It's difficult to find failures.
• Interface faults cannot be distinguished easily
  from other types of faults.

11
SANDWICH

Test
Test
Test
Test
A
G
A
E
F
Test
Test
D,G
B,E,F
Test
A,B,C,D, E,F,G
12
SANDWICH

• Combines a Top-Down and a Bottom-Up approach.
• System is viewed as three layers, just like a
  sandwich (the target layer in the middle, the
  levels above and below).
• Testing converges on the target layer.
• Stubs for utilities need not be written.
• Does not test the individual components
  throroughly

13
MODIFIED SANDWICH

Test
Test
Test
Test
A
G
A
E
F
Test
Test
D
Test
Test
B
D,G
B,E,F
Test
Test
C
A,B,C,D, E,F,G
14
MODIFIED SANDWICH

• Allows upper-level components to be tested before
  merging them with others.

15
Comparison of Integration Strategies

• Handout