feat: add pytest-embedded-espemu service for esp-emu (CII-245)

[shubhamdp]

Description

Add a new espemu service that runs tests on esp-emulator, Espressif's emulator for ESP RISC-V series SoCs, instead of a real target — analogous to the existing qemu service:

pytest --embedded-services idf,espemu --target esp32c3

How it works:

• EspEmuApp merges the app's flash files into a single image (esptool merge-bin, no flash-size padding needed)

• EspEmu launches esp-emu with UART0 on stdio, so DUT I/O rides the standard DuplicateStdoutPopen` redirection — no serial ports or TCP bridges involved

• hard_reset raises NotImplementedError, which IdfUnityDutMixin already handles by re-triggering the Unity test menu

• New CLI options: --espemu-image-path, --espemu-prog-path, --espemu-cli-args, --espemu-extra-args (e.g. "--net user,restrict=yes" to isolate tests from LAN multicast noise)

• Supported targets: esp32c3, esp32c6, esp32h2, esp32p4, esp32s31; other targets fail with a clear error.

• Motivation: an emulator-backed DUT lets test suites that today run on QEMU or real hardware run anywhere with a single static binary — notably faster and with less CI setup.

• Naming: went with espemu to keep the service key, fixture, module, and CLI prefix identical (like qemu)

Related

• https://github.com/espressif/esp-emulator

Testing

• pytest-embedded-espemu/tests/test_espemu.py — pytester-based tests mirroring the qemu service's, against the hello_world_esp32c3 fixture app (skipped when esp-emu is not on PATH): basic expect, multi-count with two emulator instances, and the unsupported-target error

• pytest-embedded/tests/test_base.py — service-to-classes parametrization extended with idf,espemu (covers the plugin wiring without needing the emulator binary)

• New test-espemu job in test-python.yml installs esp-emu via its upstream install script and runs the tests with coverage

• Full suite also verified in a clean venv (bash foreach.sh install) on macOS

• Also verified with the esp-matter project where this unit-test-app is ran with this pytest-plugin using esp-emu

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Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.

[github-actions]

Title	Coverage	Tests	Skipped	Failures	Errors	Time
Qemu		7	0 💤	0 ❌	0 🔥	22.629s ⏱️
3.14 X64		120	19 💤	0 ❌	0 🔥	15m 28s ⏱️
Espemu		3	0 💤	0 ❌	0 🔥	3.322s ⏱️
3.10 ARM64		120	21 💤	0 ❌	0 🔥	12m 48s ⏱️

[hfudev]

Thank you. All looks good to me. I'll merge it and release the 2.9.0 version next Monday

[shubhamdp]

Thank you. All looks good to me. I'll merge it and release the 2.9.0 version next Monday

Thank you!