Replace manually messing with coverage options by using --cov-append. Also add a cleaning phase.

Author: ionelmc

examples/src-layout/tox.ini

@@ -1,15 +1,13 @@
 [tox]
-envlist = pypy3,py39,report
+envlist = clean,pypy310,py310,report
 
 [tool:pytest]
 testpaths = tests
 addopts =
     --cov-report=term-missing
 
 [testenv]
-setenv =
-    py{py3,39}: COVERAGE_FILE = .coverage.{envname}
-commands = pytest --cov {posargs:-vv}
+commands = pytest --cov --cov-append {posargs:-vv}
 deps =
     pytest
     coverage
@@ -20,12 +18,17 @@ deps =
     ../..
 
 depends =
-    report: pypy3,py39
+    report: pypy310,py310
+    {pypy310,py310}: clean
+
+[testenv:clean]
+skip_install = true
+deps = coverage
+commands =
+    coverage erase
 
 [testenv:report]
 skip_install = true
 deps = coverage
 commands =
-    coverage combine
-    coverage html
     coverage report --fail-under=100