A Test-Driven Development (TDD) workflow was followed throughout the project. Every component — from the lowest-level file reader to the GUI window — has a corresponding Google Test suite that was written before (or alongside) the production code. This ensures each module behaves correctly in isolation and makes regressions immediately visible.

SysfsRead class

SysfsReader (include/SysfsRead.hpp, src/core/SysfsRead.cxx) is the lowest-level component. It opens a sysfs-like file and translates its raw text content into a SysfsStatus enum:

File content	Status
`"1"`	`Enabled`
`"error: temp too high"`	`ErrorTempTooHigh`
empty / whitespace-only	`Empty`
file missing	`Unreachable`
anything else	`UnexpectedValue`

The reader never throws on I/O errors; every outcome is expressed through the enum so callers can react without exception handling. A helper trim_in_place strips trailing whitespace and newlines before comparison.

Tests: tests/test_sysfs_read.cxx — covers all five status branches by writing controlled content to a temporary file.

Producer class / thread

Producer (include/Producer.hpp, src/core/Producer.cxx) runs a worker std::thread that periodically polls the SysfsReader and, when the status is Enabled, generates a random integer and forwards it through an injected send_fn callback. The polling interval is 1 second under normal conditions and 7 seconds when the sysfs file reports ErrorTempTooHigh (cool-down).

UnixIpcBridge

Note

why unix domain sockets? Because I have more experience with them under linux than with posix shared memmory and semaphore, and I find them easier to unit-test.

UnixIpcBridge (include/UnixIpcBridge.hpp, src/core/UnixIpcBridge.cxx) is a small helper that connects to a UNIX domain socket and sends a single int per call. It opens a new connection for each value, which keeps the protocol stateless and simple.

Tests: tests/test_unix_ipc.cxx — spins up a fake socket server, sends values through the bridge, and asserts they arrive correctly.

ConsumerThread

ConsumerThread (include/ConsumerThread.hpp, src/core/ConsumerThread.cxx) is a QObject that listens on a UNIX domain socket in a background std::thread. On each received integer it:

Prints the value to stdout.
Emits the valueReceived(int) Qt signal.

The server socket is created and bound inside start() before the thread is spawned, so the socket is guaranteed to be ready by the time start() returns — eliminating race conditions with the producer. Graceful shutdown is handled by stop(), which shuts down the file descriptor to unblock the blocking accept() call.

Tests: tests/test_consumer_thread.cxx — uses QSignalSpy to verify single-value, multi-value, negative, and zero reception.