Software Testing - Exploratory Testing Techniques and Heuristics

Exploratory Testing is a simultaneous process of learning, test design, and test execution.
Structured exploratory testing goes beyond random testing by using defined techniques and heuristics to systematically discover defects.

Key idea: Think, test, observe, adapt — continuously

Why Structured Exploratory Testing Is Needed

Simple exploratory testing can become:

• Random

• Incomplete

• Tester-dependent

Structured techniques ensure:

• Better coverage

• Repeatability

• Measurable outcomes

• Higher defect discovery

1. Session-Based Exploratory Testing (SBET)

SBET introduces structure and accountability.

Key elements:

• Time-boxed sessions (usually 60–120 minutes)

• Charter (clear mission for the session)

• Notes and observations

• Debriefing after session

Example Charter:

“Explore login failures for invalid credentials and session timeout behavior.”

Benefits:

• Focused exploration

• Trackable effort

• Better reporting

2. Heuristic-Based Exploratory Testing

Heuristics are mental shortcuts or rules of thumb that guide where and how to test.

They do not guarantee correctness, but increase defect detection probability.

a) SFDPOT Heuristic

Used to explore data-related risks.

• Structure

• Function

• Data

• Platform

• Operations

• Time

Example:
Test how data behaves over time, during upgrades, or under platform changes.

b) CRUD Heuristic

Used for data-centric systems.

• Create

• Read

• Update

• Delete

Example:
Verify behavior when deleting data that is referenced elsewhere.

c) Boundary Value Heuristic

Focuses on edge conditions.

• Minimum values

• Maximum values

• Empty inputs

• Null values

Especially effective in forms, APIs, and validations.

d) Error Guessing Heuristic

Based on tester experience.

• Common failure points

• Past defects

• Developer mistakes

Example:
Testing empty passwords, SQL injection strings, invalid formats.

3. Tour-Based Exploratory Testing

Testing is guided by predefined “tours” of the application.

Common tours:

• Feature Tour – main features

• Data Tour – data flow and storage

• Error Tour – error handling paths

• Interruption Tour – failures, crashes, restarts

• Configuration Tour – settings and preferences

Benefit:
Ensures systematic coverage without scripts.

4. Mind Mapping Technique

Uses visual maps to explore test ideas.

Process:

• Start with feature at center

• Branch into scenarios

• Add edge cases dynamically

Advantages:

• Encourages creative thinking

• Helps avoid missed areas

• Useful in early testing phases

5. Risk-Based Exploratory Testing

Exploration focuses on high-risk areas.

Risk factors:

• New or changed code

• Complex logic

• Integration points

• Business-critical features

Outcome:
Maximum defect discovery in minimal time.

Exploratory Testing vs Scripted Testing

Advantages of Structured Exploratory Testing

• Finds critical and hidden defects

• Adapts quickly to change

• Complements automated testing

• Effective when requirements are unclear

Limitations

• Depends on tester skill

• Hard to automate

• Needs discipline to stay structured