Leveling Up API Endpoint Testing Game: Test Cases Design, Execution Tips and Tricks

As an experienced QA Automation Engineer, I understand the importance of designing effective test cases for API endpoints. In this guide, I will walk you through the process of creating test cases using case-based testing and equivalence partitioning for the endpoint https://restcountries.com/v3.1/independent/.

Test Case Design:

Test case design is a critical phase of the software testing process. It is essential to create well-designed test cases that cover all the functional requirements of the API endpoint. In this section, we will look at how to create test cases for API endpoints.

a) Create test cases for API endpoints:

The first step in creating test cases for API endpoints is to understand the API specification. This involves reading the API documentation to identify the available endpoints, their inputs, and expected outputs. Once you have a clear understanding of the API, you can start designing your test cases.

To create test cases for API endpoints, you need to consider the following:

i) Inputs: Identify the inputs required by each endpoint. These inputs could be query parameters, request headers, or request bodies.

ii) Outputs: Determine the expected outputs for each endpoint. These outputs could be response codes, response headers, or response bodies.

iii) Error conditions: Identify the error conditions for each endpoint. These could be invalid inputs, missing inputs, or unauthorized requests.

iv) Edge cases: Consider the edge cases for each endpoint. These are scenarios that are unlikely to occur but could cause issues if not handled correctly.

b) Use case-based testing:

Use case-based testing is a technique used to design test cases based on real-world scenarios. It involves identifying the different ways users interact with the system and designing test cases to cover these scenarios.

To use case-based testing, you need to consider the following:

i) User roles: Identify the different user roles that interact with the system. For the endpoint https://restcountries.com/v3.1/independent/, these could be admins, regular users, or guests.

ii) User actions: Identify the different actions that users can perform on the system. For the endpoint https://restcountries.com/v3.1/independent/, these could be retrieving information, updating information, creating new information, or deleting information.

iii) User scenarios: Identify the different scenarios that users can encounter when using the system. For the endpoint https://restcountries.com/v3.1/independent/, these could be retrieving information for a specific country, updating information for a specific country, creating a new country, or deleting a country.

c) Equivalence partitioning:

Equivalence partitioning is a technique used to divide a set of inputs into groups that are expected to behave similarly. It involves identifying the different input values and dividing them into groups based on their expected behavior.

To use equivalence partitioning, you need to consider the following:

i) Input values: Identify the different input values required by each endpoint. These could be numeric values, text values, or Boolean values.

ii) Equivalence classes: Divide the input values into groups based on their expected behavior. For example, for a numeric input, you could divide the values into negative values, zero, and positive values.

iii) Test cases: Design test cases to cover each equivalence class. For example, for a numeric input, you could create test cases for negative values, zero, and positive values.

Test Case Execution:

Once you have designed your test cases, the next step is to execute them. In this section, we will look at how to execute test cases for the endpoint https://restcountries.com/v3.1/independent/ using the GET, PUT, POST, and DELETE API methods.

a) GET Method:

The GET method is used to retrieve information from the endpoint. To execute test cases using the GET method, you need to i) Identify the test cases: Identify the test cases that require the GET method. For example, retrieving information for a specific country.

ii) Execute the test cases: Execute the test cases by sending a GET request to the endpoint with the required inputs. Verify that the expected outputs are returned.

iii) Verify the response: Verify that the response code is 200 OK and that the response body contains the expected information.

b) PUT Method:

The PUT method is used to update information in the endpoint. To execute test cases using the PUT method, you need to:

i) Identify the test cases: Identify the test cases that require the PUT method. For example, updating information for a specific country.

ii) Execute the test cases: Execute the test cases by sending a PUT request to the endpoint with the required inputs. Verify that the expected outputs are returned.

iii) Verify the response: Verify that the response code is 200 OK and that the response body contains the updated information.

c) POST Method:

The POST method is used to create new information in the endpoint. To execute test cases using the POST method, you need to:

i) Identify the test cases: Identify the test cases that require the POST method. For example, creating a new country.

ii) Execute the test cases: Execute the test cases by sending a POST request to the endpoint with the required inputs. Verify that the expected outputs are returned.

iii) Verify the response: Verify that the response code is 201 Created and that the response body contains the newly created information.

d) DELETE Method:

The DELETE method is used to delete information from the endpoint. To execute test cases using the DELETE method, you need to:

i) Identify the test cases: Identify the test cases that require the DELETE method. For example, deleting a specific country.

ii) Execute the test cases: Execute the test cases by sending a DELETE request to the endpoint with the required inputs. Verify that the expected outputs are returned.

iii) Verify the response: Verify that the response code is 204 No Content and that the deleted information is no longer available.

Conclusion:

Test cases designing effective test cases for API endpoints is essential to ensure that the endpoint functions correctly. By using case-based testing and equivalence partitioning, you can create well-designed test cases that cover all functional requirements of the endpoint. When executing the test cases, it is important to use the appropriate API methods and verify that the expected outputs are returned.