feat!: remove fullcoverage, it doesn't work in 3.13

CPython stopped using it in python/cpython#88054

Author: nedbat

CHANGES.rst

@@ -34,9 +34,14 @@ Unreleased
 
 - The new 3.12 soft keyword ``type`` is properly bolded in HTML reports.
 
+- Removed the "fullcoverage" feature used by CPython to measure the coverage of
+  early-imported standard library modules.  CPython `stopped using it
+  <88054_>`_ in 2021, and it stopped working completely in Python 3.13.
+
 .. _issue 1605: https://github.com/nedbat/coveragepy/pull/1605
 .. _issue 1684: https://github.com/nedbat/coveragepy/issues/1684
 .. _pull 1685: https://github.com/nedbat/coveragepy/pull/1685
+.. _88054: https://github.com/python/cpython/issues/88054
 
 
 .. scriv-start-here

MANIFEST.in

@@ -31,7 +31,6 @@ recursive-include lab *
 recursive-include .github *
 
 recursive-include coverage *.pyi
-recursive-include coverage/fullcoverage *.py
 recursive-include coverage/ctracer *.c *.h
 
 recursive-include doc *.py *.in *.pip *.rst *.txt *.png

coverage/collector.py

@@ -11,7 +11,7 @@
 
 from types import FrameType
 from typing import (
-    cast, Any, Callable, Dict, List, Mapping, Optional, Set, Tuple, Type, TypeVar,
+    cast, Any, Callable, Dict, List, Mapping, Optional, Set, Type, TypeVar,
 )
 
 from coverage import env
@@ -24,7 +24,7 @@
 from coverage.plugin import CoveragePlugin
 from coverage.pytracer import PyTracer
 from coverage.types import (
-    TArc, TFileDisposition, TLineNo, TTraceData, TTraceFn, TTracer, TWarnFn,
+    TArc, TFileDisposition, TTraceData, TTraceFn, TTracer, TWarnFn,
 )
 
 os = isolate_module(os)
@@ -330,18 +330,9 @@ def start(self) -> None:
 
         self.tracers = []
 
-        # Check to see whether we had a fullcoverage tracer installed. If so,
-        # get the stack frames it stashed away for us.
-        traces0: List[Tuple[Tuple[FrameType, str, Any], TLineNo]] = []
-        fn0 = sys.gettrace()
-        if fn0:
-            tracer0 = getattr(fn0, '__self__', None)
-            if tracer0:
-                traces0 = getattr(tracer0, 'traces', [])
-
         try:
             # Install the tracer on this thread.
-            fn = self._start_tracer()
+            self._start_tracer()
         except:
             if self._collectors:
                 self._collectors[-1].resume()
@@ -351,13 +342,6 @@ def start(self) -> None:
         # stack of collectors.
         self._collectors.append(self)
 
-        # Replay all the events from fullcoverage into the new trace function.
-        for (frame, event, arg), lineno in traces0:
-            try:
-                fn(frame, event, arg, lineno=lineno)
-            except TypeError as ex:
-                raise RuntimeError("fullcoverage must be run with the C trace function.") from ex
-
         # Install our installation tracer in threading, to jump-start other
         # threads.
         if self.threading:

coverage/ctracer/tracer.c

@@ -857,24 +857,14 @@ CTracer_trace(CTracer *self, PyFrameObject *frame, int what, PyObject *arg_unuse
  * means it must be callable to be used in sys.settrace().
  *
  * So we make ourself callable, equivalent to invoking our trace function.
- *
- * To help with the process of replaying stored frames, this function has an
- * optional keyword argument:
- *
- *      def CTracer_call(frame, event, arg, lineno=0)
- *
- * If provided, the lineno argument is used as the line number, and the
- * frame's f_lineno member is ignored.
  */
 static PyObject *
 CTracer_call(CTracer *self, PyObject *args, PyObject *kwds)
 {
     PyFrameObject *frame;
     PyObject *what_str;
     PyObject *arg;
-    int lineno = 0;
     int what;
-    int orig_lineno;
     PyObject *ret = NULL;
     PyObject * ascii = NULL;
 
@@ -888,10 +878,10 @@ CTracer_call(CTracer *self, PyObject *args, PyObject *kwds)
         NULL
         };
 
-    static char *kwlist[] = {"frame", "event", "arg", "lineno", NULL};
+    static char *kwlist[] = {"frame", "event", "arg", NULL};
 
     if (!PyArg_ParseTupleAndKeywords(args, kwds, "O!O!O|i:Tracer_call", kwlist,
-            &PyFrame_Type, &frame, &PyUnicode_Type, &what_str, &arg, &lineno)) {
+            &PyFrame_Type, &frame, &PyUnicode_Type, &what_str, &arg)) {
         goto done;
     }
 
@@ -913,21 +903,12 @@ CTracer_call(CTracer *self, PyObject *args, PyObject *kwds)
     Py_DECREF(ascii);
     #endif
 
-    /* Save off the frame's lineno, and use the forced one, if provided. */
-    orig_lineno = frame->f_lineno;
-    if (lineno > 0) {
-        frame->f_lineno = lineno;
-    }
-
     /* Invoke the C function, and return ourselves. */
     if (CTracer_trace(self, frame, what, arg) == RET_OK) {
         Py_INCREF(self);
         ret = (PyObject *)self;
     }
 
-    /* Clean up. */
-    frame->f_lineno = orig_lineno;
-
     /* For better speed, install ourselves the C way so that future calls go
        directly to CTracer_trace, without this intermediate function.
 

coverage/fullcoverage/encodings.py

@@ -26,8 +26,7 @@ warn_unused_configs = true
 warn_unused_ignores = true
 
 exclude = """(?x)(
-    ^coverage/fullcoverage/encodings\\.py$      # can't import things into it.
-    | ^tests/balance_xdist_plugin\\.py$         # not part of our test suite.
+    ^tests/balance_xdist_plugin\\.py$           # not part of our test suite.
     )"""
 
 ## PYLINT

pyproject.toml

@@ -87,7 +87,6 @@
     package_data={
         'coverage': [
             'htmlfiles/*.*',
-            'fullcoverage/*.*',
             'py.typed',
         ]
     },

setup.py

@@ -556,30 +556,6 @@ def f():
         )
         assert msg in out
 
-    @pytest.mark.expensive
-    @pytest.mark.skipif(not env.C_TRACER, reason="fullcoverage only works with the C tracer.")
-    @pytest.mark.skipif(env.METACOV, reason="Can't test fullcoverage when measuring ourselves")
-    def test_fullcoverage(self) -> None:
-        # fullcoverage is a trick to get stdlib modules measured from
-        # the very beginning of the process. Here we import os and
-        # then check how many lines are measured.
-        self.make_file("getenv.py", """\
-            import os
-            print("FOOEY == %s" % os.getenv("FOOEY"))
-            """)
-
-        fullcov = os.path.join(os.path.dirname(coverage.__file__), "fullcoverage")
-        self.set_environ("FOOEY", "BOO")
-        self.set_environ("PYTHONPATH", fullcov)
-        out = self.run_command("python -X frozen_modules=off -m coverage run -L getenv.py")
-        assert out == "FOOEY == BOO\n"
-        data = coverage.CoverageData()
-        data.read()
-        # The actual number of executed lines in os.py when it's
-        # imported is 120 or so.  Just running os.getenv executes
-        # about 5.
-        assert line_counts(data)['os.py'] > 50
-
     # Pypy passes locally, but fails in CI? Perhaps the version of macOS is
     # significant?  https://foss.heptapod.net/pypy/pypy/-/issues/3074
     @pytest.mark.skipif(env.PYPY, reason="PyPy is unreliable with this test")