diff --git a/.Rbuildignore b/.Rbuildignore
index ca584cf..d9bb52d 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -1,3 +1,4 @@
 ^README.Rmd$
 ^README.md$
 ^\.github$
+^codecov\.yml$
diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 1ab118b..a2d2629 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -29,3 +29,27 @@ jobs:
           needs: check
 
       - uses: r-lib/actions/check-r-package@v2
+      
+            - name: Test coverage
+        run: |
+          covr::codecov(
+            quiet = FALSE,
+            clean = FALSE,
+            install_path = file.path(Sys.getenv("RUNNER_TEMP"), "package")
+          )
+        shell: Rscript {0}
+
+      - name: Show testthat output
+        if: always()
+        run: |
+          ## --------------------------------------------------------------------
+          find ${{ runner.temp }}/package -name 'testthat.Rout*' -exec cat '{}' \; || true
+        shell: bash
+
+      - name: Upload test results
+        if: failure()
+        uses: actions/upload-artifact@v3
+        with:
+          name: coverage-test-failures
+          path: ${{ runner.temp }}/package
+
diff --git a/README.Rmd b/README.Rmd
index 8bf0123..b89744e 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -9,6 +9,7 @@ editor_options:
 [![License: GPL v3](https://img.shields.io/badge/License-GPLv3-green.svg)](https://www.gnu.org/licenses/gpl-3.0)
 [![Lifecycle: experimental](https://img.shields.io/badge/lifecycle-maturing-blue.svg)](https://www.tidyverse.org/lifecycle/#maturing)
 [![R-CMD-check](https://github.com/PolMine/duplicates/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/PolMine/duplicates/actions/workflows/R-CMD-check.yaml)
+[![Codecov test coverage](https://codecov.io/gh/PolMine/duplicates/branch/devel/graph/badge.svg)](https://app.codecov.io/gh/PolMine/duplicates?branch=devel)
 <!-- badges: end -->
 
 
diff --git a/README.md b/README.md
index 11e025d..4c43d80 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,8 @@ v3](https://img.shields.io/badge/License-GPLv3-green.svg)](https://www.gnu.org/l
 [![Lifecycle:
 experimental](https://img.shields.io/badge/lifecycle-maturing-blue.svg)](https://www.tidyverse.org/lifecycle/#maturing)
 [![R-CMD-check](https://github.com/PolMine/duplicates/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/PolMine/duplicates/actions/workflows/R-CMD-check.yaml)
+[![Codecov test
+coverage](https://codecov.io/gh/PolMine/duplicates/branch/devel/graph/badge.svg)](https://app.codecov.io/gh/PolMine/duplicates?branch=devel)
 <!-- badges: end -->
 
 ## About
diff --git a/codecov.yml b/codecov.yml
new file mode 100644
index 0000000..04c5585
--- /dev/null
+++ b/codecov.yml
@@ -0,0 +1,14 @@
+comment: false
+
+coverage:
+  status:
+    project:
+      default:
+        target: auto
+        threshold: 1%
+        informational: true
+    patch:
+      default:
+        target: auto
+        threshold: 1%
+        informational: true