Module testing

Testing tools for configurations.

Overview

On the most basic level, testing allows to ensure that a configuration can be parsed from the expected data format. Additionally, tests can help ensure that no breaking changes are made to the configuration code, and can serve as documentation.

• test() function parses a config source, such as (parsed) YAML or mocked env vars.
• test_complete() additionally requires that the source is complete, i.e. covers all config params, recursively if there are any sub-configs. Naturally, for enum configs, a single variant is required (but this variant still must be completely covered).
• test_minimal(), conversely, requires that only required config params are specified in the source. This allows to check for breaking changes caused by adding non-optional params to a config.
• Tester enables more control over the test setup, such as testing entire ConfigSchema (as opposed to single configs), mocking env variables etc.

Examples

See test(), test_complete() and test_minimal() docs for basic examples of usage.

Mocking env variables

This is mostly useful for testing fallbacks that read from env variables, although the mocked env vars are respected by Environment config sources as well.

use smart_config::{
    fallback, testing::Tester,
    DescribeConfig, DeserializeConfig, Environment,
};

#[derive(DescribeConfig, DeserializeConfig)]
struct TestConfig {
    port: u16,
    #[config(
        default_t = "/tmp".into(),
        fallback = &fallback::Env("TMPDIR")
    )]
    temp_dir: PathBuf,
}

let config: TestConfig = Tester::default()
    .set_env("TMPDIR", "/var/app")
    .set_env("APP_PORT", "8080")
    .test_complete(Environment::prefixed("APP_"))?;
assert_eq!(config.port, 8_080);
assert_eq!(config.temp_dir.as_os_str(), "/var/app");

Structs

Tester

Test case builder that allows configuring deserialization options etc.

Functions

test

Tests config deserialization from the provided sample. Takes into account param aliases, performs sample preprocessing etc.

test_complete

Tests config deserialization ensuring that all declared config params are covered.

test_minimal

Tests config deserialization ensuring that only required config params are covered. This is useful to detect new required params (i.e., backward-incompatible changes).