PYTHON-5467 Add codecov integration

.codecov.yml

@@ -0,0 +1,5 @@
+comment:  # this is a top-level key
+  layout: " diff, flags, files"
+  behavior: default
+  require_changes: true
+  require_base: false

.evergreen/config.yml

@@ -38,6 +38,7 @@ post:
   # Disabled, causing timeouts
   # - func: "upload working dir"
   - func: "teardown system"
+  - func: "upload codecov"
   - func: "upload coverage"
   - func: "upload mo artifacts"
   - func: "upload test results"

.evergreen/generated_configs/functions.yml

@@ -252,6 +252,25 @@ functions:
           - TOOLCHAIN_VERSION
       type: test
 
+  # Upload coverage codecov
+  upload codecov:
+    - command: subprocess.exec
+      params:
+        binary: bash
+        args:
+          - .evergreen/scripts/upload-codecov.sh
+        working_dir: src
+        silent: true
+        include_expansions_in_env:
+          - CODECOV_TOKEN
+          - build_variant
+          - task_name
+          - github_commit
+          - github_pr_number
+          - github_pr_head_branch
+          - github_author
+      type: test
+
   # Upload coverage
   upload coverage:
     - command: ec2.assume_role

.evergreen/scripts/generate_config.py

@@ -1077,6 +1077,26 @@ def create_upload_coverage_func():
     return "upload coverage", [get_assume_role(), cmd]
 
 
+def create_upload_coverage_codecov_func():
+    # Upload the coverage xml report to codecov.
+    include_expansions = [
+        "CODECOV_TOKEN",
+        "build_variant",
+        "task_name",
+        "github_commit",
+        "github_pr_number",
+        "github_pr_head_branch",
+        "github_author",
+    ]
+    args = [
+        ".evergreen/scripts/upload-codecov.sh",
+    ]
+    upload_cmd = get_subprocess_exec(
+        silent=True, include_expansions_in_env=include_expansions, args=args
+    )
+    return "upload codecov", [upload_cmd]
+
+
 def create_download_and_merge_coverage_func():
     include_expansions = ["AWS_ACCESS_KEY_ID", "AWS_SECRET_ACCESS_KEY", "AWS_SESSION_TOKEN"]
     args = [

.evergreen/scripts/setup_tests.py

@@ -458,7 +458,7 @@ def handle_test_env() -> None:
         # Keep in sync with combine-coverage.sh.
         # coverage >=5 is needed for relative_files=true.
         UV_ARGS.append("--group coverage")
-        TEST_ARGS = f"{TEST_ARGS} --cov"
+        TEST_ARGS = f"{TEST_ARGS} --cov --cov-report=xml"
         write_env("COVERAGE")
 
     if opts.green_framework:

.evergreen/scripts/upload-codecov.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+# shellcheck disable=SC2154
+# Upload a coverate report to codecov.
+set -eux
+
+echo "Inside upload-codecov script"
+
+if [ -z "${github_pr_number:-}" ]; then
+  echo "This is not a PR, not running codecov"
+  exit 0
+fi
+
+if [ ! -f "xunit-results/TEST-results.xml" ]; then
+  echo "There are no XML test results, not running codecov"
+  exit 0
+fi
+
+# TODO: handle linux and windows.
+curl -Os https://cli.codecov.io/latest/linux/codecov
+curl -Os https://cli.codecov.io/latest/linux/codecov.SHA256SUM
+shasum -a 256 -c codecov.SHA256SUM
+sudo chmod +x codecov
+./codecov upload-process \
+  --report-type test_results \
+  --disable-search \
+  --fail-on-error \
+  --token ${CODECOV_TOKEN} \
+  --pr ${github_pr_number} \
+  --sha "${github_commit}" \
+  --branch "${github_author}:${github_pr_head_branch}" \
+  --flag "${build_variant}-${task_name}" \
+  --file xunit-results/TEST-results.xml

.github/workflows/test-python.yml

@@ -79,6 +79,36 @@ jobs:
       - name: Run tests
         run: uv run --extra test pytest -v
 
+  coverage:
+    # This enables a coverage report for a given PR, which will be augmented by
+    # the combined codecov report uploaded in Evergreen.
+    runs-on: ubuntu-latest
+
+    name: Coverage
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+      - name: Install uv
+        uses: astral-sh/setup-uv@61cb8a9741eeb8a550a1b8544337180c0fc8476b # v7
+        with:
+          enable-cache: true
+          python-version: "3.10"
+      - id: setup-mongodb
+        uses: mongodb-labs/drivers-evergreen-tools@master
+        with:
+          version: "8.0"
+      - name: Install just
+        run: uv tool install rust-just
+      - name: Setup tests
+        run: COVERAGE=1 just setup-tests
+      - name: Run tests
+        run: just run-tests
+      - name: Upload test results to Codecov
+        uses: codecov/codecov-action@671740ac38dd9b0130fbe1cec585b89eea48d3de # v5
+        with:
+          report_type: test_results
+          token: ${{ secrets.CODECOV_TOKEN }}
   doctest:
     runs-on: ubuntu-latest
     name: DocTest