Testing

Unit Tests (Mocked)

The tests/ directory contains host-only tests that replace the low-level lw_* functions with mocks. They exercise buffer semantics, repeated-start flows, timeout handling, and the strict scanner behavior.

Running locally 

cmake --preset dev
cmake --build --preset dev
ctest --preset dev

Presets require CMake 3.20 or newer. If you are on an older CMake, the raw cmake -S . -B build flow remains supported as a fallback.

Tests covered:

  • Plain requestFrom using lw_read
  • Repeated-start reads via lw_ioctl_read
  • Internal register helper (requestFrom(addr, qty, iaddress, isize, sendStop))
  • Timeout flag propagation when lw_read reports ETIMEDOUT
  • Deferred write flushing when endTransmission(false) is not followed by a read
  • Deferred write failure handling before follow-on operations
  • Strict scanner write failures (logging suppressed in that binary)
  • Basic negative-path checks for the C API (lw_open_bus, lw_write, lw_ioctl_write, closed-handle errno handling, etc.)

Hardware Tests

Mock tests catch logic regressions, but you should still validate on real hardware before tagging releases:

  1. Setup: Attach an I2C peripheral to /dev/i2c-1. You can use the Arduino companion sketch in examples, which exposes a simple slave at 0x40. Ensure i2c-dev is loaded (sudo modprobe i2c-dev).
  2. Scanner: From build/, run sudo ./i2c_scanner. Confirm your peripheral shows up (the Arduino sketch will report at 0x40).
  3. Writer: Run sudo ./master_writer (or pass --help to adjust bus/address/register). Watch the Arduino serial log to confirm the byte was received.
  4. Reader / Repeated Start: Run sudo ./master_reader. It performs endTransmission(false) followed by requestFrom(), verifying the repeated-start path.
  5. Extended exercise: sudo ./master_multiplier writes a rolling pattern, then reads it back, providing a simple stress test.
  6. Custom tests: Integrate linux_wire into your application and validate against the target device(s).

Continuous Integration

.github/workflows/ci.yml runs on ubuntu-22.04 for every push/PR targeting main. Steps:

  1. Checkout
  2. Install cmake, ninja-build, gcc, g++
  3. cmake --preset dev
  4. cmake --build --preset dev
  5. ctest --preset dev

CI ensures both the library and tests build cleanly on a baseline similar to Raspberry Pi OS. Always run the hardware checks above before releasing.