ci: upload test coverage on codecov.io

.github/workflows/check.yaml

@@ -60,6 +60,7 @@ jobs:
           command: fetch
           args: --locked
 
+
   lsif:
     name: Generate LSIF index and upload it to Sourcegraph
     needs: [fetch]
@@ -71,7 +72,6 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Install toolchain
-        id: toolchain
         uses: actions-rs/toolchain@v1
         with:
           toolchain: nightly
@@ -104,6 +104,7 @@ jobs:
         run: |
           src lsif upload -file=./dump.lsif -indexer=rust-analyzer -repo="github.com/${GITHUB_REPOSITORY}" -commit="${GITHUB_SHA}" -github-token="${{ secrets.GITHUB_TOKEN }}"
 
+
   rustfmt:
     name: Check style
     needs: [fetch]
@@ -241,6 +242,53 @@ jobs:
           command: test
           args: --offline
 
+
+  coverage:
+    name: Code coverage
+    needs: [rustfmt, clippy, fetch]
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout the code
+        uses: actions/checkout@v2
+
+      - name: Install toolchain
+        id: toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          target: x86_64-unknown-linux-musl
+          override: true
+
+      - name: Setup Cargo cache
+        uses: actions/cache@v2.1.6
+        with:
+          path: |
+            ~/.cargo/registry/index
+            ~/.cargo/registry/cache
+            ~/.cargo/git/db
+          key: ${{ runner.os }}-cargo-deps-msrv-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Setup build cache
+        uses: actions/cache@v2.1.6
+        with:
+          path: |
+            target
+          key: ${{ runner.os }}-cargo-coverage-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-coverage-${{ steps.toolchain.outputs.rustc_hash }}-
+            ${{ runner.os }}-cargo-coverage-
+
+      - name: Run cargo tarpaulin
+        uses: actions-rs/tarpaulin@v0.1
+        with:
+          version: '0.18.2'
+          args: '--avoid-cfg-tarpaulin'
+
+      - name: Upload to codecov.io
+        uses: codecov/codecov-action@v2
+
+
   build-image:
     name: Build and push Docker image
     needs: [rustfmt, clippy]