Error Types

All fallible operations in cargo-ninety-nine return Result<T, NinetyNineError>.

`NinetyNineError`

A comprehensive error enum covering all failure modes, derived with thiserror.

#![allow(unused)]
fn main() {
pub enum NinetyNineError {
    ConfigParse { source: toml::de::Error },
    ConfigIo { path: PathBuf, source: std::io::Error },
    NoRunnerAvailable,
    RunnerExecution { message: String },
    InvalidConfig { message: String },
    BinaryDiscovery { message: String },
    TestListing { binary: PathBuf, message: String },
    TestNotFound { name: String },
    FilterParse { message: String },
    Io { source: std::io::Error },
    Json { source: serde_json::Error },
    Storage { source: rusqlite::Error },
    PostgresStorage { source: tokio_postgres::Error },
    PostgresPool { message: String },
}
}

Error Categories

Configuration Errors

Variant	Display Message	Cause
`ConfigParse`	`failed to parse config: {source}`	TOML syntax error or invalid field value
`ConfigIo`	`failed to read config file {path}: {source}`	File exists but cannot be read (permissions, etc.)
`InvalidConfig`	`invalid configuration: {message}`	Logical configuration error (e.g., Postgres backend without connection config)

Runner Errors

Variant	Display Message	Cause
`NoRunnerAvailable`	`no test runner available: install cargo-nextest or use cargo test`	Neither cargo-nextest nor cargo test found
`RunnerExecution`	`runner execution failed: {message}`	Test binary failed to spawn or produced unexpected output
`BinaryDiscovery`	`binary discovery failed: {message}`	`cargo test --no-run` failed or produced unparseable output
`TestListing`	`test listing failed for {binary}: {message}`	Test binary `--list` invocation failed
`TestNotFound`	`test not found: {name}`	Requested test does not exist in the project

Filter Errors

Variant	Display Message	Cause
`FilterParse`	`filter parse error: {message}`	Invalid filter DSL syntax

Storage Errors

Variant	Display Message	Cause
`Storage`	`storage error: {source}`	SQLite operation failed (auto-converted from `rusqlite::Error`)
`PostgresStorage`	`postgres storage error: {source}`	PostgreSQL operation failed (auto-converted from `tokio_postgres::Error`)
`PostgresPool`	`postgres pool error: {message}`	Connection pool exhausted or configuration error

I/O and Serialization Errors

Variant	Display Message	Cause
`Io`	`io error: {source}`	Generic I/O failure (auto-converted from `std::io::Error`)
`Json`	`json serialization error: {source}`	JSON serialization/deserialization failure (auto-converted from `serde_json::Error`)

Automatic Conversions

The following From implementations allow ? propagation:

Source Type	Target Variant
`std::io::Error`	`Io`
`serde_json::Error`	`Json`
`rusqlite::Error`	`Storage`
`tokio_postgres::Error`	`PostgresStorage`

Error Handling in Practice

All errors are displayed to stderr in the main entry point and cause the process to exit with code 1:

#![allow(unused)]
fn main() {
// Simplified from main.rs
match run(args).await {
    Ok(()) => {}
    Err(e) => {
        eprintln!("error: {e}");
        std::process::exit(1);
    }
}
}

When --verbose is enabled, the tracing subscriber is set to debug level, providing additional context before errors surface.

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cargo ninety-nine