Allow implicit ResourceListProcessorFunc (#760)

* allow explicit ResourceListProcessorFunc, add test

Signed-off-by: Mózes László Máté <laszlo.mozes@nokia.com>

* return to using switch-case, add test for lambda function

Signed-off-by: Mózes László Máté <laszlo.mozes@nokia.com>

* address copilot comment

Signed-off-by: Mózes László Máté <laszlo.mozes@nokia.com>

* expose global `make test`

Signed-off-by: Mózes László Máté <laszlo.mozes@nokia.com>

* add nil check in Run

Signed-off-by: Mózes László Máté <laszlo.mozes@nokia.com>

---------

Signed-off-by: Mózes László Máté <laszlo.mozes@nokia.com>

Author: mozesl-nokia

Makefile

@@ -9,4 +9,8 @@ GO_MOD_DIRS = $(shell find . -name 'go.mod' -exec sh -c 'echo \"$$(dirname "{}")
 
 .PHONY: tidy
 tidy:
-	@for f in $(GO_MOD_DIRS); do (cd $$f; echo "Tidying $$f"; go mod tidy) || exit 1; done
+	@for f in $(GO_MOD_DIRS); do (cd $$f; echo "Tidying $$f"; go mod tidy) || exit 1; done
+
+.PHONY: test
+test:
+	make -C go test

go/Makefile

@@ -40,7 +40,7 @@ lint: $(MODULES)
 
 .PHONY: test
 test: $(MODULES)
-	@for f in $(^D); do (cd $$f; echo "Testing $$f"; go test ./...) || exit 1; done
+	@for f in $(^D); do (cd $$f; echo "Testing $$f"; go test -v ./...) || exit 1; done
 
 .PHONY: vet
 vet: $(MODULES)

go/fn/run.go

@@ -87,11 +87,11 @@ func AsMain(input any, opts ...Option) error {
 
 	err := func() error {
 		var p ResourceListProcessor
-		switch input := input.(type) {
-		case runnerProcessor:
-			p = input
-		case ResourceListProcessorFunc:
-			p = input
+		switch cast := input.(type) {
+		case ResourceListProcessor:
+			p = cast
+		case func(*ResourceList) (bool, error):
+			p = ResourceListProcessorFunc(cast)
 		default:
 			return fmt.Errorf("unknown input type %T", input)
 		}
@@ -206,13 +206,8 @@ func readFilesAsResourceList(paths []string) (*ResourceList, error) {
 // Run evaluates the function. input must be a resourceList in yaml format. An
 // updated resourceList will be returned.
 func Run(p ResourceListProcessor, input []byte) ([]byte, error) {
-	switch input := p.(type) {
-	case runnerProcessor:
-		p = input
-	case ResourceListProcessorFunc:
-		p = input
-	default:
-		return nil, fmt.Errorf("unknown input type %T", input)
+	if p == nil {
+		return nil, fmt.Errorf("nil ResourceListProcessor")
 	}
 	rl, err := ParseResourceList(input)
 	if err != nil {

go/fn/run_test.go

@@ -16,6 +16,7 @@ package fn
 
 import (
 	"fmt"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -33,3 +34,53 @@ func TestRunEmptyInputBytes(t *testing.T) {
 	expected := fmt.Appendf(nil, "apiVersion: %s\nkind: %s\n", kio.ResourceListAPIVersion, kio.ResourceListKind)
 	assert.Equal(t, expected, output)
 }
+
+type myRLP struct{}
+
+func (*myRLP) Process(*ResourceList) (bool, error) {
+	return true, nil
+}
+
+func myRLPF(*ResourceList) (bool, error) {
+	return true, nil
+}
+
+type myFR struct{}
+
+func (*myFR) Run(*Context, *KubeObject, KubeObjects, *Results) bool {
+	return true
+}
+
+var _ ResourceListProcessor = &myRLP{}
+var _ ResourceListProcessorFunc = myRLPF
+var _ Runner = &myFR{}
+
+func TestAsMainTypes(t *testing.T) {
+	oldArgs := os.Args
+	t.Cleanup(func() { os.Args = oldArgs })
+	os.Args = []string{"cmd"}
+
+	oldStdin := os.Stdin
+	devNull, err := os.Open(os.DevNull)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		os.Stdin = oldStdin
+		_ = devNull.Close()
+	})
+	os.Stdin = devNull
+
+	testCases := map[string]any{
+		"ResourceListProcessor":              &myRLP{},
+		"Implicit ResourceListProcessorFunc": myRLPF,
+		"Explicit ResourceListProcessorFunc": ResourceListProcessorFunc(myRLPF),
+		"RunnerProcessor":                    runnerProcessor{ctx: t.Context(), fnRunner: &myFR{}},
+		"Anonymous":                          func(*ResourceList) (bool, error) { return true, nil },
+	}
+
+	for name, input := range testCases {
+		t.Run(name, func(t *testing.T) {
+			err := AsMain(input)
+			assert.NoError(t, err)
+		})
+	}
+}