What is the Purpose of configurePreset within buildPreset and testPreset Entries?

In CMakePresets.json, I can specify the configurePreset in both buildPreset and testPreset, but I'm not entirely sure what it actually does.

For instance:

{
  ...
  "configurePreset": {
    "name": "default",
    "toolchainFile": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake",
    "binaryDir": "build",
    "warnings": {
      "dev": false
    },
    "cacheVariables": {
      "BUILD_TESTING": true
    }
  },
  "buildPreset": {
    "name": "debug",
    "configurePreset": "default",
    "configuration": "Debug",
    "jobs": 20
  }
  ...
}

However, the following command won't work:

cmake --build --preset debug

This is because I need to configure the project first.

A build preset derives from the configuration preset a build directory.

Additionally, if you set inheritConfigureEnvironment flag for the build preset, environment variables will also be inherited.

The same is valid for a test preset: from the configuration preset it unconditionally derives build directory and optionally inherits environment variables.