fix: expose target on the emulator duts (CII-248)

[Harshal5]

Description

Any test or fixture that selects behavior by target fails under --embedded-services idf,espemu or --embedded-services idf,qemu:

AttributeError: 'EspEmuDutWithIdfUnityDutMixin' object has no attribute 'target'
AttributeError: 'QemuDutWithIdfUnityDutMixin'   object has no attribute 'target'

EspEmuDut and QemuDut both extend the plain Dut, which knows self.app but not the target. The attribute is set by IdfDut.__init__ (self.target = app.target), and IdfDut(IdfUnityDutMixin, SerialDut) is serial based, so dut_factory.py correctly picks the emulator dut classes and the attribute is simply absent.

This is not a corner case for ESP-IDF users: dut.target is referenced by ESP-IDF's root conftest.py helpers, so a large share of ESP-IDF's test cases cannot run under either emulator. Reproduced with examples/get-started/hello_world on esp32c3 for both services:

$ pytest examples/get-started/hello_world -k test_hello_world
          --target esp32c3 --embedded-services idf,qemu
...
conftest.py:508: in real_func
    dut.target,
E   AttributeError: 'QemuDutWithIdfUnityDutMixin' object has no attribute 'target'

Fix

Take the target from the app in both duts. EspEmuApp and QemuApp are IdfApp subclasses, so the value is available; getattr keeps it optional for other app classes, since the base App has no target.

self.target: str | None = getattr(self.app, 'target', None)

NuttxQemuDut inherits QemuDut and picks this up too, with None for apps that have no target.

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 🔥	25.465s ⏱️
3.14 X64		122	19 💤	1 ❌	0 🔥	15m 23s ⏱️
Espemu		3	0 💤	0 ❌	0 🔥	3.851s ⏱️
3.10 ARM64		122	21 💤	0 ❌	0 🔥	12m 53s ⏱️