Add coverage report.

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ name: Continuous Integration
 on: [push, pull_request]
 
 jobs:
-  build_and_test:
+  build_test_format_lint:
     name: ${{matrix.command.name}} (${{matrix.toolchain}})
     runs-on: ubuntu-latest
 
@@ -45,7 +45,8 @@ jobs:
             target
           key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
 
-      - uses: actions-rs/toolchain@v1
+      - name: Install toolchain
+        uses: actions-rs/toolchain@v1
         with:
           toolchain: ${{ matrix.toolchain }}
           override: true
@@ -57,3 +58,44 @@ jobs:
         with:
           command: ${{matrix.command.command}}
           args: ${{matrix.command.args}}
+
+  coveralls_io:
+    name: Coverage
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: ⚡ Cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Install toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+          default: true
+
+      - name: Install cargo-tarpaulin
+        uses: actions-rs/install@v0.1
+        with:
+          crate: cargo-tarpaulin
+          version: latest
+          use-tool-cache: true
+
+      - name: Coverage Report with tarpaulin
+        uses: actions-rs/cargo@v1
+        with:
+          command: tarpaulin
+          args: --manifest-path implementation/Cargo.toml --all --all-features --out Lcov -- --test-threads 1
+
+      - name: Upload Coverage
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          path-to-lcov: ./lcov.info