Merge pull request #2713 from Shell32-Natsu/empty-list-in-patch

Keep empty array in output

api/krusty/keepemptyarray_test.go

@@ -0,0 +1,48 @@
+package krusty_test
+
+import (
+	"testing"
+
+	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
+)
+
+func TestKeepEmptyArray(t *testing.T) {
+	th := kusttest_test.MakeHarness(t)
+	th.WriteF("/app/resources.yaml", `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: testing123
+spec:
+  replicas: 1
+  selector: null
+  template:
+    spec:
+      containers:
+      - name: event
+        image: testing123
+        imagePullPolicy: IfNotPresent
+      imagePullSecrets: []`)
+
+	th.WriteK("/app", `
+resources:
+- resources.yaml`)
+
+	m := th.Run("/app", th.MakeDefaultOptions())
+	th.AssertActualEqualsExpected(m, `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: testing123
+spec:
+  replicas: 1
+  selector: null
+  template:
+    spec:
+      containers:
+      - image: testing123
+        imagePullPolicy: IfNotPresent
+        name: event
+      imagePullSecrets: []
+`)
+}

kustomize/go.mod

@@ -16,3 +16,8 @@ exclude (
 	github.com/russross/blackfriday v2.0.0+incompatible
 	sigs.k8s.io/kustomize/api v0.2.0
 )
+
+replace (
+	sigs.k8s.io/kustomize/api => ../api
+	sigs.k8s.io/kustomize/kyaml => ../kyaml
+)

kyaml/yaml/types.go

@@ -28,27 +28,20 @@ func NullNode() *RNode {
 
 // IsMissingOrNull returns true if the RNode is nil or contains and explicitly null value.
 func IsMissingOrNull(node *RNode) bool {
-	if node == nil || node.YNode() == nil || node.YNode().Tag == NullNodeTag {
-		return true
-	}
-	return false
+	return node == nil || node.YNode() == nil || node.YNode().Tag == NullNodeTag
 }
 
 // IsEmpty returns true if the RNode is MissingOrNull, or is either a MappingNode with
-// no fields, or a SequenceNode with no elements.
+// no fields.
 func IsEmpty(node *RNode) bool {
-	if node == nil || node.YNode() == nil || node.YNode().Tag == NullNodeTag {
+	if IsMissingOrNull(node) {
 		return true
 	}
 
-	if node.YNode().Kind == yaml.MappingNode && len(node.YNode().Content) == 0 {
-		return true
-	}
-	if node.YNode().Kind == yaml.SequenceNode && len(node.YNode().Content) == 0 {
-		return true
-	}
-
-	return false
+	// Empty sequence is a special case and temporarily not considered as empty here.
+	// Some users may want to keep empty sequence for compatibility reason.
+	// For example, use JSON 6902 patch.
+	return node.YNode().Kind == yaml.MappingNode && len(node.YNode().Content) == 0
 }
 
 func IsNull(node *RNode) bool {
@@ -189,6 +182,28 @@ func NewListRNode(values ...string) *RNode {
 	return seq
 }
 
+// NewMapRNode returns a new Map *RNode containing the provided values
+func NewMapRNode(values *map[string]string) *RNode {
+	m := &RNode{value: &yaml.Node{
+		Kind: yaml.MappingNode,
+	}}
+	if values == nil {
+		return m
+	}
+
+	for k, v := range *values {
+		m.value.Content = append(m.value.Content, &yaml.Node{
+			Kind:  yaml.ScalarNode,
+			Value: k,
+		}, &yaml.Node{
+			Kind:  yaml.ScalarNode,
+			Value: v,
+		})
+	}
+
+	return m
+}
+
 // NewRNode returns a new RNode pointer containing the provided Node.
 func NewRNode(value *yaml.Node) *RNode {
 	return &RNode{value: value}

kyaml/yaml/types_test.go

@@ -166,3 +166,74 @@ type: string
 	}
 	assert.Equal(t, expected, actual)
 }
+
+func TestIsMissingOrNull(t *testing.T) {
+	if !IsMissingOrNull(nil) {
+		t.Fatalf("input: nil")
+	}
+	// missing value or null value
+	if !IsMissingOrNull(NewRNode(nil)) {
+		t.Fatalf("input: nil value")
+	}
+
+	if IsMissingOrNull(NewScalarRNode("foo")) {
+		t.Fatalf("input: valid node")
+	}
+	// node with NullNodeTag
+	if !IsMissingOrNull(NullNode()) {
+		t.Fatalf("input: with NullNodeTag")
+	}
+}
+
+func TestIsEmpty(t *testing.T) {
+	if !IsEmpty(nil) {
+		t.Fatalf("input: nil")
+	}
+
+	// missing value or null value
+	if !IsEmpty(NewRNode(nil)) {
+		t.Fatalf("input: nil value")
+	}
+	// not array or map
+	if IsEmpty(NewScalarRNode("foo")) {
+		t.Fatalf("input: not array or map")
+	}
+}
+
+func TestIsEmpty_Arrays(t *testing.T) {
+	node := NewListRNode()
+	// empty array. empty array is not expected as empty
+	if IsEmpty(node) {
+		t.Fatalf("input: empty array")
+	}
+	// array with 1 item
+	node = NewListRNode("foo")
+	if IsEmpty(node) {
+		t.Fatalf("input: array with 1 item")
+	}
+	// delete the item in array
+	node.value.Content = nil
+	if IsEmpty(node) {
+		t.Fatalf("input: empty array")
+	}
+}
+
+func TestIsEmpty_Maps(t *testing.T) {
+	node := NewMapRNode(nil)
+	// empty map
+	if !IsEmpty(node) {
+		t.Fatalf("input: empty map")
+	}
+	// map with 1 item
+	node = NewMapRNode(&map[string]string{
+		"foo": "bar",
+	})
+	if IsEmpty(node) {
+		t.Fatalf("input: map with 1 item")
+	}
+	// delete the item in map
+	node.value.Content = nil
+	if !IsEmpty(node) {
+		t.Fatalf("input: empty map")
+	}
+}