Add Tekton downstream test

.github/workflows/knative-downstream.yaml

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-name: Downstream
+name: Downstream Knative
 
 on:
   pull_request:

.github/workflows/tekton-downstream.yaml

@@ -0,0 +1,64 @@
+# Copyright 2020 The Knative Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Downstream Tekton
+
+on:
+  pull_request:
+    branches: [ 'main', 'master', 'release-*' ]
+
+jobs:
+
+  downstream-tekton:
+    name: Unit Test
+
+    strategy:
+      fail-fast: false # Keep running if one leg fails.
+      matrix:
+        include:
+          - repo: pipeline
+            org: tektoncd
+
+    runs-on: ubuntu-latest
+
+    env:
+      GOPATH: ${{ github.workspace }}
+
+    steps:
+
+    - name: Set up Go 1.16.x
+      uses: actions/setup-go@v2
+      with:
+        go-version: 1.16.x
+
+    - name: Install Dependencies
+      run: |
+        go get github.com/google/go-licenses
+
+    - name: Checkout Upstream
+      uses: actions/checkout@v2
+      with:
+        path: ./src/knative.dev/${{ github.event.repository.name }}
+
+    - name: Checkout Downstream
+      uses: actions/checkout@v2
+      with:
+        repository: ${{ matrix.org }}/${{ matrix.repo }}
+        path: ./src/github.com/${{ matrix.org }}/${{ matrix.repo }}
+
+    - name: Test Downstream
+      uses: knative-sandbox/[email protected]
+      with:
+        upstream-module: knative.dev/${{ github.event.repository.name }}
+        downstream-module: github.com/${{ matrix.org }}/${{ matrix.repo }}