Check test coverage improvement #548

.github/workflows/test-coverage.yml

@@ -60,3 +60,33 @@ jobs:
           name: coverage-test-failures
           path: ${{ runner.temp }}/package
 
+       - name: Get coverage from main branch
+        run: |
+          git fetch origin main
+          git checkout main -- tests/coverage.rds || true
+          echo "Fetching main branch coverage data"
+
+       - name: Compare coverage and fail on decrease
+         run: |
+          Rscript -e '
+          library(covr)
+          pr_coverage <- package_coverage()
+          saveRDS(pr_coverage, "tests/coverage.rds")
+
+          if (file.exists("tests/coverage.rds")) {
+            main_coverage <- readRDS("tests/coverage.rds")
+            pr_cov <- percent_coverage(pr_coverage)
+            main_cov <- percent_coverage(main_coverage)
+
+            message("Coverage on main: ", main_cov, "%")
+            message("Coverage on PR: ", pr_cov, "%")
+
+            if (pr_cov < main_cov) {
+              stop("❌ Test coverage decreased! PR coverage: ", pr_cov, "% vs. Main: ", main_cov, "%")
+            } else {
+              message("✅ Coverage is maintained or improved.")
+            }
+           } else {
+             message("⚠️ No previous coverage data found. Skipping comparison.")
+           }
+