Add coverage

.github/workflows/coverage.yml

@@ -0,0 +1,34 @@
+name: Coverage
+
+on:
+  push:
+    branches:
+      - '*'
+  pull_request:
+    branches:
+      - '*'
+
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest  # Works on Windows/macOS too, adjust if needed
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # Ensures Git history is available for Coveralls
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: llvm-tools-preview  # Needed for cargo-llvm-cov
+
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+
+      - name: Generate coverage data
+        run: |
+          cargo llvm-cov --lcov --output-path lcov.info
+
+      - name: Coveralls GitHub Action
+        uses: coverallsapp/github-action@v2.3.6

README.md

@@ -1,6 +1,7 @@
 # picojson
 
 [![Build and test](https://github.com/kaidokert/picojson-rs/actions/workflows/build.yaml/badge.svg)](https://github.com/kaidokert/picojson-rs/actions/workflows/build.yaml)
+[![Coverage Status](https://coveralls.io/repos/github/kaidokert/picojson-rs/badge.svg?branch=main)](https://coveralls.io/github/kaidokert/picojson-rs?branch=main)
 
 A minimal Rust JSON **pull-parser** for resource-constrained environments.