feat: adds coverage badge workflow

.github/workflows/go-coverage.yml

@@ -0,0 +1,42 @@
+name: Coverage
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v5
+      with:
+        fetch-depth: '0'
+
+    - name: Set up Go
+      uses: actions/setup-go@v6
+      with:
+        go-version: 1.24
+        cache: 'true'
+
+    - name: Build
+      run: go install
+
+    - name: Test
+      run: |
+        go test -v -cover ./... -coverprofile coverage.out -coverpkg ./...
+        go tool cover -func coverage.out -o coverage.out  # Replaces coverage.out with the analysis of coverage.out
+
+    - name: Go Coverage Badge
+      uses: tj-actions/coverage-badge-go@v3
+      with:
+        green: 80
+        filename: coverage.out
+
+    - uses: stefanzweifel/git-auto-commit-action@v6
+      id: auto-commit-action
+      with:
+        commit_message: Apply Code Coverage Badge
+        file_pattern: ./README.md

README.md

@@ -1,9 +1,11 @@
 # envconfig
-A small,
-dependency-free Go library for loading configuration from environment variables directly into your structs.
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/struct0x/envconfig.svg)](https://pkg.go.dev/github.com/struct0x/envconfig)
 [![Go Report Card](https://goreportcard.com/badge/github.com/struct0x/envconfig)](https://goreportcard.com/report/github.com/struct0x/envconfig)
+![Coverage](https://img.shields.io/badge/Coverage-87.6%25-brightgreen)
+
+A small,
+dependency-free Go library for loading configuration from environment variables directly into your structs.
 
 It supports nested structs, prefixes, defaults, required fields,
 slices, maps, arrays, pointers, durations, and custom (un)marshalers.