tests(ci): add coverage

.github/workflows/ci.yml

@@ -61,9 +61,24 @@ jobs:
           cargo set-version ${{ needs.setup_release.outputs.release_version }}
 
       - name: Test
+        id: test
         uses: ./ci/github-actions/arch-run
         with:
-          command: cargo test
+          command: cargo install cargo-tarpaulin; cargo tarpaulin --out Xml
+
+      - name: Upload coverage
+        # any except canceled or skipped
+        if: >-
+          always() &&
+          (steps.test.outcome == 'success' || steps.test.outcome == 'failure') &&
+          startsWith(github.repository, 'LizardByte/')
+        uses: codecov/codecov-action@v4
+        with:
+          disable_search: true
+          fail_ci_if_error: true
+          files: ./target/debug/tarpaulin/report.xml
+          token: ${{ secrets.CODECOV_TOKEN }}
+          verbose: true
 
       - name: Clippy
         uses: ./ci/github-actions/arch-run

codecov.yml

@@ -0,0 +1,19 @@
+---
+codecov:
+  branch: master
+
+coverage:
+  status:
+    project:
+      default:
+        target: auto
+        threshold: 10%
+
+comment:
+  layout: "diff, flags, files"
+  behavior: default
+  require_changes: false  # if true: only post the comment if coverage changes
+
+ignore:
+  - "tests"
+  - "third-party"