Better support for writing functions in go

kyaml/fn/framework/framework_test.go

@@ -0,0 +1,53 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package framework_test
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/kyaml/fn/framework"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func TestCommand_dockerfile(t *testing.T) {
+	d, err := ioutil.TempDir("", "kustomize")
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+	defer os.RemoveAll(d)
+
+	// create a function
+	cmd := framework.Command(nil, func(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+		return nil, nil
+	})
+
+	// generate the Dockerfile
+	cmd.SetArgs([]string{"gen", d})
+	if !assert.NoError(t, cmd.Execute()) {
+		t.FailNow()
+	}
+
+	b, err := ioutil.ReadFile(filepath.Join(d, "Dockerfile"))
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+
+	expected := `FROM golang:1.13-stretch
+ENV CGO_ENABLED=0
+WORKDIR /go/src/
+COPY . .
+RUN go build -v -o /usr/local/bin/function ./
+
+FROM alpine:latest
+COPY --from=0 /usr/local/bin/function /usr/local/bin/function
+CMD ["function"]
+`
+	if !assert.Equal(t, expected, string(b)) {
+		t.FailNow()
+	}
+}