Add documentation for running tests

- Instructions for running tests in mock and live environments.
- Setup details for environment configuration.

ballerina/tests/README.md

@@ -0,0 +1,89 @@
+# Running Tests
+
+## Prerequisites
+
+You need an API key from OpenAI.
+
+To obtain this, refer to the [Ballerina OpenAI Images Connector](https://github.com/ballerina-platform/module-ballerinax-openai.images/blob/main/ballerina/Module.md).
+
+## Test Environments
+
+There are two test environments for running the `openai.images` connector tests. The default environment is a mock server for the OpenAI API. The other environment is the actual OpenAI API.
+
+You can run the tests in either of these environments, and each has its own compatible set of tests.
+
+| Test Groups | Environment                                       |
+|-------------|---------------------------------------------------|
+| mock_tests  | Mock server for OpenAI API (Default Environment)  |
+| live_tests  | OpenAI API                                        |
+
+## Running Tests in the Mock Server
+
+To execute the tests on the mock server, ensure that the `isLiveServer` environment variable is either set to `false` or left unset before initiating the tests.
+
+This environment variable can be configured within the `Config.toml` file located in the `tests` directory or specified as an environment variable.
+
+### Using a `Config.toml` File
+
+Create a `Config.toml` file in the `tests` directory with the following content:
+
+```toml
+isLiveServer = false
+```
+
+### Using Environment Variables
+
+Alternatively, you can set the environment variable directly.
+
+For Linux or macOS:
+
+```bash
+export isLiveServer=false
+```
+
+For Windows:
+
+```bash
+setx isLiveServer false
+```
+
+Then, run the following command to execute the tests:
+
+```bash
+./gradlew clean test
+```
+
+## Running Tests Against the OpenAI Live API
+
+### Using a `Config.toml` File
+
+Create a `Config.toml` file in the `tests` directory and add your authentication credentials:
+
+```toml
+isLiveServer = true
+apiKey = "<your-openAI-api-key>"
+```
+
+### Using Environment Variables
+
+Alternatively, you can set your authentication credentials as environment variables.
+
+For Linux or macOS:
+
+```bash
+export isLiveServer=true
+export apiKey="<your-openAI-api-key>"
+```
+
+For Windows:
+
+```bash
+setx isLiveServer true
+setx apiKey <your-openAI-api-key>
+```
+
+Then, run the following command to execute the tests:
+
+```bash
+./gradlew clean test
+```