Add tests

.github/workflows/test-dotnet.yml

@@ -0,0 +1,31 @@
+name: Validate dotnet
+
+on:
+  pull_request:
+    paths-ignore:
+      - '**.md'
+  push:
+    branches:
+      - main
+      - releases/*
+    paths-ignore:
+      - '**.md'
+
+jobs:
+  setup-version:
+    runs-on: ${{ matrix.operating-system }}
+    strategy:
+      fail-fast: false
+      matrix:
+        operating-system: [ubuntu-latest, windows-latest, macOS-latest]
+        dotnet-version: [2.1, 2.2, 3.1, 5.0]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Clear toolcache
+        shell: pwsh
+        run: __tests__/clear-toolcache.ps1 ${{ runner.os }}
+      - name: Setup dotnet ${{ matrix.dotnet-version }}
+        uses: ./
+        with:
+          dotnet-version: "${{ matrix.dotnet-version }}"