File Matching API

Overview

The File Matching API provides a convenient way to test file operations in your code. It allows you to:

• Record file writes during test execution
• Assert on file content using flexible matchers
• Match files by path suffix to handle variable paths
• Provide detailed error messages for failed assertions

Usage

Basic Example

#![allow(unused)]
fn main() {
use ubrn_cli_testing::{start_recording, stop_recording, File, assert_files};
use ubrn_common::write_file;

#[test]
fn test_my_function_writes_correct_files() {
    // Start recording file operations
    start_recording();

    // Call your function that writes files
    my_function_that_writes_files();

    // Assert on the files that were written
    assert_files(&[
        // Match a file with exact path suffix
        File::new("output.json")
            .contains("\"status\": \"success\"")
            .does_not_contain("error"),

        // Match another file using path suffix
        File::new("/src/generated/types.kt")
            .contains("class User")
    ]);

    // Clean up recording state
    stop_recording();
}
}

Available Matchers

The API provides two content matchers:

1. .contains(substring) - Asserts that the file content contains the specified substring
2. .does_not_contain(substring) - Asserts that the file content does not contain the substring

Path Matching

File paths are matched using suffix matching, which means you only need to provide the unique part of the path:

#![allow(unused)]
fn main() {
// This will match any file ending with "/src/main.kt"
File::new("/src/main.kt")

// This will match any file named "config.json"
File::new("config.json")
}

Functions

• start_recording() - Begins recording file operations
• stop_recording() - Stops recording and clears recorded files
• assert_files(files) - Asserts that files matching the provided patterns were written
• files_match(files) - Returns true if files match the patterns, false otherwise

Integration with Command Recording

The file matching API integrates seamlessly with the existing command recording functionality:

#![allow(unused)]
fn main() {
use ubrn_cli_testing::{start_recording, stop_recording, Command, assert_commands, File, assert_files};

#[test]
fn test_function_generates_files_and_runs_commands() {
    start_recording();

    my_function();

    // Assert on commands
    assert_commands(&[
        Command::new("npm").arg("install"),
        Command::new("cargo").arg("build")
    ]);

    // Assert on files
    assert_files(&[
        File::new("package.json").contains("\"name\": \"my-package\""),
        File::new("src/index.js").contains("export default")
    ]);

    stop_recording();
}
}