docs: add brief info about testing, pytest, coverage

docs/dev-guide/testing.md

@@ -2,6 +2,128 @@
 
 ## Types of Testing
 
+- **Unit Testing:**
+
+  - Focuses on testing individual units or components of a software in isolation.
+  - Validates that each unit of code performs as designed.
+
+- **Integration Testing:**
+
+  - Verifies that different units or modules work together as expected.
+  - Identifies issues in interactions between integrated components.
+
+- **Functional Testing:**
+
+  - Validates that the software functions according to specified requirements.
+  - Ensures that the system behaves as expected from the end-users' perspective.
+
+- **Regression Testing:**
+
+  - Ensures that new code changes don't negatively impact existing functionalities.
+  - Detects unintended side effects caused by modifications.
+
+- **Acceptance Testing:**
+
+  - Validates that the entire system meets the specified requirements
+    and is accepted by stakeholders.
+  - Can include user acceptance testing (UAT) and business acceptance testing.
+
+- **Performance Testing:**
+
+  - Evaluates the system's responsiveness, scalability, and stability
+    under different conditions.
+  - Includes load testing, stress testing, and scalability testing.
+
+- **Security Testing:**
+
+  - Identifies vulnerabilities and weaknesses in the software's security features.
+  - Ensures that sensitive data is protected and the system is resistant to attacks.
+
+- **Usability Testing:**
+
+  - Assesses the software's user interface, user experience, and overall
+    user-friendliness.
+  - Focuses on how easily users can interact with and navigate through the application.
+
+- **Compatibility Testing:**
+
+  - Ensures that the software functions correctly across different
+    devices, browsers, and operating systems.
+  - Verifies compatibility with various configurations.
+
+- **Smoke Testing:**
+
+  - A subset of tests to verify basic functionality and ensure the
+    stability of a new build.
+  - Quick checks performed before more comprehensive testing.
+
+- **Exploratory Testing:**
+
+  - Informal testing approach where testers explore the application to find defects.
+  - Emphasizes discovery and learning during the testing process.
+
+- **White Box Testing:**
+
+  - Examines the internal logic, code structure, and implementation
+    details of the software.
+  - Requires knowledge of the internal workings of the application.
+
+- **Black Box Testing:**
+
+  - Tests the software's functionality without knowing its internal code or logic.
+  - Focuses on inputs and outputs, treating the software as a "black box".
+
+- **Ad-hoc Testing:**
+
+  - Informal and unplanned testing approach.
+  - Testers explore the application without predefined test cases.
+
+- **Alpha Testing:**
+
+  - Conducted by a select group of users before the software's public release.
+  - Focuses on identifying major issues before wider deployment.
+
+- **Beta Testing:**
+  - Conducted by a larger group of users in a real-world environment.
+  - Gathers feedback from end-users to improve the software before the final release.
+
 ## Python
 
+### PyTest
+
+- PyTest is a popular **unit testing** framework for Python, with more
+  in-built functionality than the standard Python `unittest` module.
+- It has a simple and concise syntax, many plugins, plus async support,
+  and detailed / informative reporting.
+- Two major advantages are:
+  - Fixtures: allows you to set up and tear down resources during
+    testing, for example database entries.
+  - Parameterised testing: allowing you to run the same test with
+    different input values.
+
+Usage:
+
+```bash
+pytest
+```
+
+### Coverage
+
+- The concept of coverage is to determine the amount of your code that
+  is executed during unit tests.
+- This metric is a rough approximation of how thoroughly your tests
+  actually test your code.
+
+Usage:
+
+```bash
+coverage run -m pytest
+```
+
+Generating reports:
+
+```bash
+coverage report -m
+```
+
 ## Javascript