feat: coverage run now sets the COVERAGE_RUN environment variable

CHANGES.rst

@@ -23,12 +23,18 @@ This list is detailed and covers changes in each pre-release version.
 Unreleased
 ----------
 
-- When sorting human-readable names, numeric components are sorted correctly:
- file10.py will appear after file9.py. This applies to file names, module
- names, environment variables, and test contexts.
+- Feature: Coverage now sets an environment variable, ``COVERAGE_RUN`` when
+ running your code with the ``coverage run`` command. The value is not
+ important, and may change in the future. Closes `issue 553`_.
 
-- Branch coverage measurement is faster, though you might only notice on
- code that is executed many times, such as long-running loops.
+- Fix: When sorting human-readable names, numeric components are sorted
+ correctly: file10.py will appear after file9.py. This applies to file names,
+ module names, environment variables, and test contexts.
+
+- Performance: Branch coverage measurement is faster, though you might only
+ notice on code that is executed many times, such as long-running loops.
+
+ .. _issue 553: https://github.com/nedbat/coveragepy/issues/553
 
 
 .. _changes_602:

coverage/cmdline.py

@@ -6,6 +6,7 @@
 
 import glob
 import optparse # pylint: disable=deprecated-module
+import os
 import os.path
 import shlex
 import sys
@@ -739,6 +740,8 @@ def do_run(self, options, args):
  )
  return ERR
 
+ os.environ["COVERAGE_RUN"] = "true"
+
  runner = PyRunner(args, as_module=bool(options.module))
  runner.prepare()
 

coverage/version.py

@@ -5,7 +5,7 @@
 # This file is exec'ed in setup.py, don't import anything!
 
 # Same semantics as sys.version_info.
-version_info = (6, 0, 3, "alpha", 0)
+version_info = (6, 1, 0, "alpha", 0)
 
 
 def _make_version(major, minor, micro, releaselevel, serial):

doc/cmd.rst

@@ -137,6 +137,10 @@ If your coverage results seem to be overlooking code that you know has been
 executed, try running coverage.py again with the ``--timid`` flag. This uses a
 simpler but slower trace method, and might be needed in rare cases.
 
+Coverage.py sets an environment variable, ``COVERAGE_RUN`` to indicate that
+your code is running under coverage measurement. The value is not relevant,
+and may change in the future.
+
 
 .. _cmd_warnings:
 

tests/test_process.py

@@ -39,7 +39,7 @@ def test_save_on_exit(self):
  self.run_command("coverage run mycode.py")
  self.assert_exists(".coverage")
 
- def test_environment(self):
+ def test_tests_dir_is_importable(self):
  # Checks that we can import modules from the tests directory at all!
  self.make_file("mycode.py", """\
  import covmod1
@@ -53,6 +53,21 @@ def test_environment(self):
  self.assert_exists(".coverage")
  assert out == 'done\n'
 
+ def test_coverage_run_envvar_is_in_coveragerun(self):
+ # Test that we are setting COVERAGE_RUN when we run.
+ self.make_file("envornot.py", """\
+ import os
+ print(os.environ.get("COVERAGE_RUN", "nope"))
+ """)
+ self.del_environ("COVERAGE_RUN")
+ # Regular Python doesn't have the environment variable.
+ out = self.run_command("python envornot.py")
+ assert out == "nope\n"
+ self.del_environ("COVERAGE_RUN")
+ # But `coverage run` does have it.
+ out = self.run_command("coverage run envornot.py")
+ assert out == "true\n"
+
  def make_b_or_c_py(self):
  """Create b_or_c.py, used in a few of these tests."""
  # "b_or_c.py b" will run 6 lines.