Improve GitHub Action and also test Go 1.12

.github/workflows/test.yml

@@ -1,59 +1,30 @@
 name: Test
-on: [push]
+on: [push, pull_request]
 jobs:
-  linux:
-    name: Linux
-    runs-on: ubuntu-latest
+  test:
+    name: Test
+    strategy:
+      matrix:
+        go-version: [1.12.x, 1.13.x]
+        platform: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{matrix.platform}}
     steps:
-      - name: Set up Go 1.13
+      - name: Set up Go ${{matrix.go-version}}
         uses: actions/setup-go@v1
         with:
-          go-version: 1.13
+          go-version: ${{matrix.go-version}}
         id: go
 
       - name: Check out code into the Go module directory
         uses: actions/checkout@v1
 
-      - name: Build
-        run: go build -o ./task -v ./cmd/task
-
-      - name: Test
-        run: ./task test
-
-  windows:
-    name: Windows
-    runs-on: windows-latest
-    steps:
-      - name: Set up Go 1.13
-        uses: actions/setup-go@v1
-        with:
-          go-version: 1.13
-        id: go
-
-      - name: Check out code into the Go module directory
-        uses: actions/checkout@v1
+      - name: Download Go modules
+        run: go mod download
+        env:
+          GOPROXY: https://proxy.golang.org
 
       - name: Build
-        run: go install -v ./cmd/task
+        run: go build -o ./bin/task -v ./cmd/task
 
       - name: Test
-        run: go test -v ./...
-
-  macos:
-    name: MacOS
-    runs-on: macOS-latest
-    steps:
-      - name: Set up Go 1.13
-        uses: actions/setup-go@v1
-        with:
-          go-version: 1.13
-        id: go
-
-      - name: Check out code into the Go module directory
-        uses: actions/checkout@v1
-
-      - name: Build
-        run: go build -o ./task -v ./cmd/task
-
-      - name: Test
-        run: ./task test
+        run: ./bin/task test