Add coverage reporting, bypass bootstrap

requirements.txt

@@ -0,0 +1,4 @@
+# NOTE: setuptools and zc.buildout versions must be in sync with:
+# ztk-versions.cfg
+setuptools==38.2.4
+zc.buildout==2.10.0

tox.ini

@@ -1,16 +1,38 @@
 [tox]
 envlist =
+    coverage-clean,
     py27,
     py34,
     py35,
     py36,
     pypy,
-    pypy3
+    pypy3,
+    coverage-report
 
 [testenv]
 commands =
-    coverage run -m zope.testrunner --test-path=src {posargs:-vc}
+    coverage run --source=grokcore.formlib -m zope.testrunner --test-path=src {posargs:-vc}
+setenv =
+  COVERAGE_FILE=.coverage.{envname}
 deps =
     .[test]
     zope.testrunner
     coverage
+
+[testenv:coverage-clean]
+deps = coverage
+setenv =
+  COVERAGE_FILE=.coverage
+skip_install = true
+commands = coverage erase
+
+[testenv:coverage-report]
+deps = coverage
+setenv =
+  COVERAGE_FILE=.coverage
+skip_install = true
+commands =
+    coverage combine
+    coverage report
+    coverage html
+    coverage