chore: test PR comments (#41)

.github/workflows/rust.yml

@@ -14,10 +14,44 @@ jobs:
 
     runs-on: ubuntu-latest
 
+    outputs:
+      size: ${{ steps.build.outputs.size }}
+
     steps:
     - uses: actions/checkout@v2
+    - name: Install wasm-pack
+      run: |
+        curl -sSL https://github.com/rustwasm/wasm-pack/releases/download/v0.9.1/wasm-pack-v0.9.1-x86_64-unknown-linux-musl.tar.gz \
+          | tar xzO wasm-pack-v0.9.1-x86_64-unknown-linux-musl/wasm-pack \
+          > $HOME/.cargo/bin/wasm-pack
+        chmod +x $HOME/.cargo/bin/wasm-pack
     - run: cargo test --all-features --verbose
     - run: cargo doc --verbose --all-features
+    - name: Build (Release)
+      id: build
+      run: "./build.sh --release && echo ::set-output name=size::`cat public/wasm_bg.wasm | wc -c`"
+
+  build-main:
+
+    runs-on: ubuntu-latest
+    if: ${{ github.event_name == 'pull_request' }}
+
+    outputs:
+      size: ${{ steps.build.outputs.size }}
+
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        ref: main
+    - name: Install wasm-pack
+      run: |
+        curl -sSL https://github.com/rustwasm/wasm-pack/releases/download/v0.9.1/wasm-pack-v0.9.1-x86_64-unknown-linux-musl.tar.gz \
+          | tar xzO wasm-pack-v0.9.1-x86_64-unknown-linux-musl/wasm-pack \
+          > $HOME/.cargo/bin/wasm-pack
+        chmod +x $HOME/.cargo/bin/wasm-pack
+    - name: Build (Release)
+      id: build
+      run: "./build.sh --release && echo ::set-output name=size::`cat public/wasm_bg.wasm | wc -c`"
 
   checks:
 
@@ -34,3 +68,24 @@ jobs:
       with:
         token: ${{ secrets.GITHUB_TOKEN }}
         args: --all-features -- -D warnings
+
+  report-wasm-size:
+    runs-on: ubuntu-latest
+
+    needs:
+    - build
+    - build-main
+
+    if: ${{ github.event_name == 'pull_request' }}
+
+    steps:
+    - uses: mshick/add-pr-comment@v1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        message: |
+          **Compiled size report**
+
+          | File name | Old Size | New Size |
+          | --- | --- | --- |
+          | public/wasm_bg.wasm | ${{needs.build-main.outputs.size}} | ${{needs.build.outputs.size}} |