Why Test prioritization in Testing Fundamentals? - Purpose & Use Cases

The Big Idea

What if you could catch the biggest bugs first and save hours of testing?

The Scenario

Imagine you have a huge list of tests to run before releasing a new app update. You try to run them all manually, one by one, checking each feature carefully.

But the deadline is tight, and you start feeling overwhelmed.

The Problem

Running every test manually takes too long and is tiring.

You might miss important bugs because you run tests in no particular order.

Some tests are more important but get delayed, risking bad software reaching users.

The Solution

Test prioritization helps you decide which tests to run first based on importance and risk.

This way, you catch the biggest problems early and save time by focusing on what matters most.

Before vs After

✗ Before

run_all_tests_in_any_order()

✓ After

run_tests_in_priority_order()

What It Enables

It lets teams deliver better software faster by focusing on the most critical tests first.

Real Life Example

Before a big sale, an online store runs tests on payment and checkout features first, ensuring customers can buy without issues.

Key Takeaways

Manual testing of all cases wastes time and risks missing key bugs.

Test prioritization orders tests by importance and risk.

This approach improves efficiency and software quality.

Practice

1. What is the main goal of test prioritization in software testing?

easy

A. To run the most important tests first to find bugs faster

B. To run all tests in alphabetical order

C. To skip tests that are easy to pass

D. To run tests only after the software is released

Solution

1. Step 1: Understand the purpose of test prioritization

   Test prioritization means deciding which tests to run first based on their importance or likelihood to find bugs.

2. Step 2: Identify the correct goal

   The goal is to save time and find bugs faster by running important tests first.

3. Final Answer:

   To run the most important tests first to find bugs faster -> Option A

4. Quick Check:

   Test prioritization = run important tests first [OK]

Hint: Remember: prioritize tests that catch bugs quickly [OK]

Common Mistakes:

• Thinking test order is random
• Believing all tests have equal priority
• Skipping tests without reason

2. Which of the following is a good factor to consider when prioritizing tests?

easy

A. The number of testers available

B. The color of the test case document

C. The font size used in test descriptions

D. Recent changes in the code

Solution

1. Step 1: Identify relevant factors for test prioritization

   Good factors include recent code changes, past failures, and test importance.

2. Step 2: Choose the factor related to code changes

   Recent changes in code can introduce new bugs, so tests covering those areas should run first.

3. Final Answer:

   Recent changes in the code -> Option D

4. Quick Check:

   Prioritize tests by recent code changes [OK]

Hint: Focus on code changes, not irrelevant details [OK]

Common Mistakes:

• Choosing unrelated factors like document color
• Ignoring recent code updates
• Confusing tester count with test priority

3. Given the following test cases and their last failure dates, which test should be run first based on test prioritization?

Test A: failed 2 days ago
Test B: passed last run
Test C: failed 10 days ago
Test D: never failed

medium

A. Test B

B. Test D

C. Test A

D. Test C

Solution

1. Step 1: Analyze failure recency

   Tests that failed recently are more likely to find bugs again, so they get higher priority.

2. Step 2: Compare failure dates

   Test A failed 2 days ago, which is more recent than Test C (10 days ago). Tests B and D did not fail recently.

3. Final Answer:

   Test A -> Option C

4. Quick Check:

   Run tests with recent failures first [OK]

Hint: Pick tests with the most recent failures first [OK]

Common Mistakes:

• Choosing tests that never failed
• Ignoring failure dates
• Picking tests that passed last run

4. You have a test suite with 4 tests. The priority order should be based on recent code changes and past failures. The current order is:

1. Test X (no recent changes, no failures)
2. Test Y (recent changes, no failures)
3. Test Z (no recent changes, failed last run)
4. Test W (recent changes, failed last run)

Which test should be run first to follow best test prioritization?

medium

A. Test W

B. Test X

C. Test Z

D. Test Y

Solution

1. Step 1: Combine recent changes and past failures

   Tests with both recent changes and past failures have highest priority.

2. Step 2: Identify test with both factors

   Test W has recent changes and failed last run, so it should run first.

3. Final Answer:

   Test W -> Option A

4. Quick Check:

   Prioritize tests with recent changes and failures [OK]

Hint: Pick tests with both recent changes and failures first [OK]

Common Mistakes:

• Ignoring one of the prioritization factors
• Running tests without recent changes first
• Choosing tests that never failed

5. A team has 5 tests with these details:

Test 1: covers critical feature, no recent changes, failed last run
Test 2: covers minor feature, recent changes, passed last run
Test 3: covers critical feature, recent changes, passed last run
Test 4: covers minor feature, no recent changes, never failed
Test 5: covers critical feature, recent changes, failed last run

Which order best follows test prioritization principles?

hard

A. Test 1, Test 5, Test 3, Test 2, Test 4

B. Test 5, Test 1, Test 3, Test 2, Test 4

C. Test 5, Test 3, Test 1, Test 2, Test 4

D. Test 4, Test 2, Test 3, Test 1, Test 5

Solution

1. Step 1: Identify highest priority tests

   Tests covering critical features with recent changes and failures have highest priority. Test 5 fits all three.

2. Step 2: Order remaining tests by priority

   Next is Test 1 (critical, failed but no recent changes), then Test 3 (critical, recent changes, passed), followed by Test 2 and Test 4 (minor features, lower priority).

3. Final Answer:

   Test 5, Test 1, Test 3, Test 2, Test 4 -> Option B

4. Quick Check:

   Prioritize critical, recent changes, failures first [OK]

Hint: Order by criticality, recent changes, then failures [OK]

Common Mistakes:

• Ignoring feature criticality
• Not combining multiple factors
• Running low priority tests first