Reenable coverate instrumentation of test files

ddtrace/internal/coverage/code.py

@@ -13,6 +13,7 @@
 from ddtrace.internal.coverage.util import collapse_ranges
 from ddtrace.internal.logger import get_logger
 from ddtrace.internal.module import ModuleWatchdog
+from ddtrace.internal.packages import is_ddtrace_pytest_test
 from ddtrace.internal.packages import is_user_code
 from ddtrace.internal.packages import platlib_path
 from ddtrace.internal.packages import platstdlib_path
@@ -327,7 +328,7 @@ def transform(self, code: CodeType, _module: ModuleType) -> CodeType:
             # Don't instrument code from standard library/site packages/etc.
             return code
 
-        if not is_user_code(code_path):
+        if not is_user_code(code_path) and not is_ddtrace_pytest_test(code_path):
             return code
 
         retval = self.instrument_code(code, _module.__package__ if _module is not None else "")

ddtrace/internal/packages.py

@@ -3,6 +3,7 @@
 from functools import singledispatch
 import inspect
 import logging
+from os import environ
 from os import fspath  # noqa:F401
 import sys
 import sysconfig
@@ -272,6 +273,14 @@ def _(path: str) -> bool:
     return not (is_stdlib(_path) or is_third_party(_path))
 
 
+def is_ddtrace_pytest_test(path: Path) -> bool:
+    """Return an relatively confident guess about whether the file relates to a pytest test run"""
+    package = filename_to_package(str(path))
+    if package is None:
+        return False
+    return package.name == "ddtrace" and "PYTEST_CURRENT_TEST" in environ and "/dd-trace-py/tests/" in str(path)
+
+
 @cached(maxsize=256)
 def is_distribution_available(name: str) -> bool:
     """Determine if a distribution is available in the current environment."""