Adding GitHub action to compare benchmarks

.github/workflows/echo.yml

@@ -62,3 +62,55 @@ jobs:
         with:
           token:
           fail_ci_if_error: false
+  benchmark:
+    needs: test
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+        go: [1.15]
+    name: Benchmark comparison ${{ matrix.os }} @ Go ${{ matrix.go }}
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Set up Go ${{ matrix.go }}
+        uses: actions/setup-go@v1
+        with:
+          go-version: ${{ matrix.go }}
+
+      - name: Set GOPATH and PATH
+        run: |
+          echo "GOPATH=$(dirname $GITHUB_WORKSPACE)" >> $GITHUB_ENV
+          echo "$(dirname $GITHUB_WORKSPACE)/bin" >> $GITHUB_PATH
+        shell: bash
+
+      - name: Set build variables
+        run: |
+          echo "GOPROXY=https://proxy.golang.org" >> $GITHUB_ENV
+          echo "GO111MODULE=on" >> $GITHUB_ENV
+
+      - name: Checkout Code (Previous)
+        uses: actions/checkout@v2
+        with:
+          ref: ${{ github.base_ref }}
+          path: previous
+
+      - name: Checkout Code (New)
+        uses: actions/checkout@v2
+        with:
+          path: new
+
+      - name: Install Dependencies
+        run: go get -v golang.org/x/perf/cmd/benchstat
+
+      - name: Run Benchmark (Previous)
+        run: |
+          cd previous
+          go test -run="-" -bench=".*" -count=5 ./... > benchmark.txt
+
+      - name: Run Benchmark (New)
+        run: |
+          cd new
+          go test -run="-" -bench=".*" -count=5 ./... > benchmark.txt
+
+      - name: Run Benchstat
+        run: |
+          benchstat previous/benchmark.txt new/benchmark.txt