pyproject: use yowasp-yosys for tests.

This change means that tests will succeed even if the system Yosys binary is broken.
yices2 must still be present on the system.

.env.toolchain

@@ -0,0 +1,7 @@
+AMARANTH_USE_YOSYS=system
+YOSYS=yowasp-yosys
+SBY=yowasp-sby
+SMTBMC=yowasp-yosys-smtbmc
+# examples
+NEXTPNR_ICE40=yowasp-nextpnr-ice40
+ICEPACK=yowasp-icepack

.github/workflows/main.yaml

@@ -46,15 +46,9 @@ jobs:
         sudo add-apt-repository 'deb http://ppa.launchpad.net/sri-csl/formal-methods/ubuntu bionic main'
         sudo apt-get update
         sudo apt-get install yices2
-        pip install codecov yowasp-yosys
+        pip install codecov
         pdm install --dev
     - name: Run tests
-      env:
-        YOSYS: yowasp-yosys
-        NEXTPNR_ICE40: yowasp-nextpnr-ice40
-        ICEPACK: yowasp-icepack
-        SBY: yowasp-sby
-        SMTBMC: yowasp-yosys-smtbmc
       run: |
         pdm run test
     - name: Submit code coverage

pyproject.toml

@@ -49,6 +49,7 @@ includes = ["amaranth/"]
 
 [tool.pdm.dev-dependencies]
 test = [
+  "yowasp-yosys",
   "coverage",
 ]
 docs = [
@@ -62,6 +63,8 @@ examples = [
 ]
 
 [tool.pdm.scripts]
+_.env_file = ".env.toolchain"
+
 test.composite = ["test-code", "test-docs"]
 test-code.env = {PYTHONWARNINGS = "error"}
 test-code.cmd = "python -m coverage run -m unittest discover -t . -s tests -v"