PYTHON-4002 No module named coverage.__main__ (#1398)

.evergreen/combine-coverage.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+#
+# Coverage combine merges (and removes) all the coverage files and
+# generates a new .coverage file in the current directory.
+
+set -o xtrace   # Write all commands first to stderr
+set -o errexit  # Exit the script with error if any of the commands fail
+
+. .evergreen/utils.sh
+
+if [ -z "$PYTHON_BINARY" ]; then
+    PYTHON_BINARY=$(find_python3)
+fi
+
+createvirtualenv "$PYTHON_BINARY" covenv
+# coverage 7.3 dropped support for Python 3.7, keep in sync with run-tests.sh
+pip install -q "coverage<7.3"
+
+pip list
+ls -la coverage/
+
+python -m coverage combine coverage/coverage.*
+python -m coverage html -d htmlcov

.evergreen/config.yml

@@ -131,12 +131,7 @@ functions:
         working_dir: "src"
         script: |
           ${PREPARE_SHELL}
-          set -o xtrace
-          # Coverage combine merges (and removes) all the coverage files and
-          # generates a new .coverage file in the current directory.
-          ls -la coverage/
-          /opt/python/3.7/bin/python3 -m coverage combine coverage/coverage.*
-          /opt/python/3.7/bin/python3 -m coverage html -d htmlcov
+          bash .evergreen/combine-coverage.sh
     # Upload the resulting html coverage report.
     - command: shell.exec
       params:

.evergreen/run-tests.sh

@@ -258,7 +258,8 @@ python -c 'import sys; print(sys.version)'
 # Only cover CPython. PyPy reports suspiciously low coverage.
 PYTHON_IMPL=$($PYTHON -c "import platform; print(platform.python_implementation())")
 if [ -n "$COVERAGE" ] && [ "$PYTHON_IMPL" = "CPython" ]; then
-    python -m pip install pytest-cov "coverage"
+    # coverage 7.3 dropped support for Python 3.7, keep in sync with combine-coverage.sh.
+    python -m pip install pytest-cov "coverage<7.3"
     TEST_ARGS="$TEST_ARGS --cov pymongo --cov-branch --cov-report term-missing:skip-covered"
 fi