json-test

A testing library for JSON Path assertions in Rust, providing a fluent API for validating JSON structures in tests.

Features

🔍 JSONPath-based value extraction and validation
⛓️ Chainable, fluent assertion API
🎯 Type-safe operations
🧩 Property existence and value validation
📝 String pattern matching with regex support
🔢 Numeric comparisons
📦 Array and object validation
🎨 Custom matcher support

Quick Start

Add to your Cargo.toml:

[dev-dependencies]
json-test = "0.1"

Basic usage:

use json_test::JsonTest;
use serde_json::json;

#[test]
fn test_json_structure() {
    let data = json!({
        "user": {
            "name": "John Doe",
            "age": 30,
            "roles": ["user", "admin"]
        }
    });

    let mut test = JsonTest::new(&data);
    
    test.assert_path("$.user.name")
        .exists()
        .is_string()
        .equals(json!("John Doe"));
        
    test.assert_path("$.user.roles")
        .is_array()
        .has_length(2)
        .contains(&json!("admin"));
}

Main Features

Path Assertions

test.assert_path("$.user")
    .exists()
    .has_property("name")
    .has_property_value("age", json!(30));

String Operations

test.assert_path("$.user.email")
    .is_string()
    .contains_string("@")
    .matches_pattern(r"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$");

Numeric Comparisons

test.assert_path("$.user.age")
    .is_number()
    .is_greater_than(18)
    .is_less_than(100);

Array Operations

test.assert_path("$.user.roles")
    .is_array()
    .has_length(2)
    .contains(&json!("admin"));

Property Matching

test.assert_path("$.user")
    .has_properties(vec!["name", "age", "roles"])
    .properties_matching(|key| key.starts_with("meta_"))
        .count(0)
        .and()
    .has_property_matching("age", |v| v.as_u64().unwrap_or(0) > 18);

Custom Matchers

test.assert_path("$.timestamp")
    .matches(|value| {
        value.as_str()
            .map(|s| s.parse::<DateTime<Utc>>().is_ok())
            .unwrap_or(false)
    });

Examples

Looking for more examples? Check out the examples/ directory which showcases:

Basic JSON validation patterns
Advanced JSONPath queries
Property matching capabilities

Error Messages

The library provides clear, test-friendly error messages:

Property 'email' not found at $.user
Available properties: name, age, roles

Array at $.user.roles has wrong length
Expected: 3
Actual: 2

Status

This library is in active development (0.1.x). While the core API is stabilizing, minor breaking changes might occur before 1.0.

Roadmap

Enhanced array operations
Deep property traversal
Improved string operations
Additional numeric assertions

Contributing

Contributions are welcome! Please see our Contributing Guide for details.

License

Licensed under either of:

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

json-test 0.1.0