Black-box testing techniques in Software Engineering - Step-by-Step Execution

Concept Flow - Black-box testing techniques

Start Testing

↓

Identify Inputs

↓

Apply Test Cases

↓

Observe Outputs

↓

Compare with Expected Results

↓

Pass

↓

Report

↓

End Testing

Black-box testing starts by identifying inputs, applying test cases, observing outputs, and comparing them to expected results to decide pass or fail.

Execution Sample

Software Engineering

Test Case: Input=5
Expected Output=10
Run Function with Input=5
Observe Output=10
Compare Output with Expected

This example tests if the function returns 10 when given input 5, without knowing internal code.

Analysis Table

Step	Action	Input	Observed Output	Expected Output	Result	Next Step
1	Apply test case	5		10	Pending	Run function
2	Run function	5	10	10	Pending	Compare outputs
3	Compare outputs	5	10	10	Pass	Report result
4	Report result	5	10	10	Pass	End testing

💡 Test ends after output matches expected result, confirming pass.

State Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
Input	None	5	5	5	5
Observed Output	None	None	10	10	10
Expected Output	None	10	10	10	10
Result	None	Pending	Pending	Pass	Pass

Key Insights - 2 Insights

Why don't we need to know the internal code to test?

Because black-box testing focuses only on inputs and outputs, as shown in execution_table steps 1-3, ignoring internal details.

What happens if the observed output does not match expected?

The test result would be 'Fail' and debugging starts, unlike the 'Pass' shown in step 3 of execution_table.

Visual Quiz - 3 Questions

Look at the execution_table at Step 2, what is the observed output?

A 10

B 5

C None

D Pending

💡 Hint

Check the 'Observed Output' column in execution_table row for Step 2.

At which step does the test result become 'Pass'?

A Step 1

B Step 4

C Step 3

D Step 2

💡 Hint

Look at the 'Result' column in execution_table to find when it changes to 'Pass'.

If the observed output was 8 instead of 10 at Step 2, what would be the result at Step 3?

A Pending

B Fail

C Pass

D Error

💡 Hint

Compare observed and expected outputs in execution_table to determine pass or fail.

Concept Snapshot

Black-box testing checks software by giving inputs and checking outputs.
It ignores internal code details.
Test steps: input → run → observe output → compare → pass/fail.
Used to find if software meets requirements.
Focus on what software does, not how it does it.

Full Transcript

Black-box testing techniques involve testing software by focusing only on inputs and outputs without looking at internal code. The process starts by identifying inputs, applying test cases, running the software, observing outputs, and comparing them with expected results. If outputs match, the test passes; otherwise, it fails and requires debugging. This method helps verify if the software behaves as expected from the user's perspective.