The IntelliJ HTTP Client is very useful for testing APIs. We can use Javascript to look at the response and write tests with assertions about the response. If an API returns a JSON Web Token (JWT), we can use a Javascript function to decode the token and extract information from it. For example we can then assert that fields of the token have the correct value. There is no built-in support in IntelliJ HTTP Client to decode a JWT, but we can write our own Javascript function to do it. We then use the function in our Javascript response handler to decode the token.

When we use the IntelliJ HTTP Client we can write JavaScript for the pre-request and response handlers. If we want to access an environment variable in JavaScript we can use request.environment.get(string). The argument for the get function is the name of the environment variable we want to get the value for. Environment variables can be defined in the file http-client.env.json or in http-client.private.env.json.

The built-in IntelliJ HTTP Client is very useful for testing HTTP requests and responses. If we want to define a variable in our .http file that is only used in this file and will not change per environment we can define it using the following syntax: @<variable name> = variable value. The variable is an in-place variable and the scope of the variable in the current .http file. The variable is immutable and can only be defined with a value once and cannot be overwritten. To refer to the variable we use the syntax {{}}.

Sometimes we want to send HTTP requests to servers that use HTTPS with self-signed certificates. We then need to tell HTTP Client to not check the certificate of the server. This is like running the curl command with the --insecure or '-k' flag. To disable the certificate verification for HTTP Client we need to adjust the http-client.private.env.json file. For the environment we want to disable the certificate verification we must add a SSLConfiguration section. In the SSLConfiguration section we add the verifyHostCertificate property with value 'true'.