Feature:Add tests for json_schema.rs

[aryasoni98]

This PR resolves issue #1078 by adding comprehensive test coverage for the json_schema.rs file, specifically testing the public API build_json_schema() function.

Added Dependencies

• Added expect-test = "1.5.0" to Cargo.toml for snapshot-based testing

Test Implementation

• 31 comprehensive test cases covering all requirements:
  • 16 Basic type tests: All BasicValueType variants including Str, Bool, Int64, Float32, Float64, Bytes, Range, Uuid, Date, Time, LocalDateTime, OffsetDateTime, TimeDelta, Json, Vector, Union, and nullable types
  • 8 struct-type tests: Simple structs, optional fields, descriptions, nested structs, always-required options, and description extraction functionality
  • 3 Table type tests: All TableKind variants (UTable, KTable, LTable)
  • 4 Additional feature tests: Value extractor functionality, wrapper field extraction, format support options, and top-level object requirements

Key Features

• ✅ Snapshot testing using expect-test crate as suggested in the issue
• ✅ Complete API coverage of build_json_schema() function
• ✅ All configuration options in ToJsonSchemaOptions tested
• ✅ Edge cases and error conditions covered
• ✅ Maintainable test structure with helper functions and clear naming

🧪 Test Results

running 31 tests
test result: ok. 31 passed; 0 failed; 0 ignored; 0 measured; 131 filtered out

📋 Issue Requirements Met

• Add tests in json_schema.rs
• Test on the public API build_json_schema()
• Cover basic types (for types handled here)
• Cover struct types
• Cover table types
• Use expect_test crate on output serialized to JSON (as suggested)

🔍 Testing Approach

The implementation uses the expect-test crate for snapshot testing, which:

• Automatically captures the actual JSON schema output
• Compares against expected values using expect! macro
• Makes tests easier to write and maintain
• Provides clear diff output when tests fail
• Can be updated easily with UPDATE_EXPECT=1 environment variable

---

Closes #1078

This PR provides the comprehensive test coverage requested in the issue, ensuring the json_schema.rs functionality is thoroughly tested and maintainable going forward.

[georgeh0]

Thanks for the PR!