Test: refine & cache Go modules

.github/workflows/test.yml

@@ -7,6 +7,7 @@ on:
       - "**/*.go"
   pull_request:
     branches: [master]
+    types: [opened, synchronize, reopened]
     paths:
       - "**/*.go"
 
@@ -22,12 +23,15 @@ jobs:
         with:
           go-version: ^1.14
 
-      - name: Checkout default branch
+      - name: Checkout codebase
         uses: actions/checkout@v2
 
-      - name: Get dependencies
-        run: |
-          go get -v -t -d ./...
+      - name: Cache go module
+        uses: actions/cache@v2
+        with:
+          path: ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: ${{ runner.os }}-go-
 
       - name: Test
-        run: go test -parallel 1 -timeout 6h -v ./...
+        run: go test -timeout 1h -v ./...