Add test for changing struct from granular to atomic

Author: jpbetz

internal/fixture/state.go

@@ -385,6 +385,32 @@ func (f UpdateObject) preprocess(parser Parser) (Operation, error) {
 	return f, nil
 }
 
+// ChangeParser is a type of operation. It simulates making changes a schema without versioning it.
+// This can be used to test the behavior of making backward compatible schema changes, e.g.
+// setting "elementRelationship: atomic" on an existing struct. It also may be used to ensure that
+// backward incompatible changes are detected appropriately.
+type ChangeParser struct {
+	Parser *typed.Parser
+}
+
+var _ Operation = &ChangeParser{}
+
+func (cs ChangeParser) run(state *State) error {
+	state.Parser = cs.Parser
+	// Swap the schema in for use with the live object so it merges.
+	// If the schema is incompatible, this will fail validation.
+	liveWithNewSchema, err := typed.AsTyped(state.Live.AsValue(), &cs.Parser.Schema,  state.Live.TypeRef())
+	if err != nil {
+		return err
+	}
+	state.Live = liveWithNewSchema
+	return nil
+}
+
+func (cs ChangeParser) preprocess(_ Parser) (Operation, error) {
+	return cs, nil
+}
+
 // TestCase is the list of operations that need to be run, as well as
 // the object/managedfields as they are supposed to look like after all
 // the operations have been successfully performed. If Object/Managed is

merge/schema_change_test.go

@@ -0,0 +1,121 @@
+/*
+Copyright 2018 The Kubernetes 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.
+*/
+
+package merge_test
+
+import (
+	"testing"
+
+	"sigs.k8s.io/structured-merge-diff/v4/fieldpath"
+	. "sigs.k8s.io/structured-merge-diff/v4/internal/fixture"
+	"sigs.k8s.io/structured-merge-diff/v4/typed"
+)
+
+
+var structParser = func() *typed.Parser {
+	oldParser, err := typed.NewParser(`types:
+- name: v1
+  map:
+    fields:
+      - name: struct
+        type:
+          namedType: struct
+- name: struct
+  map:
+    fields:
+    - name: numeric
+      type:
+        scalar: numeric
+    - name: string
+      type:
+        scalar: string`)
+	if err != nil {
+		panic(err)
+	}
+	return oldParser
+}()
+
+var structWithAtomicParser = func() *typed.Parser {
+	newParser, err := typed.NewParser( `types:
+- name: v1
+  map:
+    fields:
+      - name: struct
+        type:
+          namedType: struct
+- name: struct
+  map:
+    fields:
+    - name: numeric
+      type:
+        scalar: numeric
+    - name: string
+      type:
+        scalar: string
+    elementRelationship: atomic`)
+	if err != nil {
+		panic(err)
+	}
+	return newParser
+}()
+
+func TestSchemaChanges(t *testing.T) {
+	tests := map[string]TestCase{
+		"change-struct-to-atomic": {
+			Ops: []Operation{
+				Apply{
+					Manager: "one",
+					Object: `
+						struct:
+						  numeric: 1
+					`,
+					APIVersion: "v1",
+				},
+				ChangeParser{Parser: structWithAtomicParser},
+				Apply{
+					Manager: "two",
+					Object: `
+						struct:
+						  string: "string"
+					`,
+					APIVersion: "v1",
+				},
+			},
+			Object: `
+				struct:
+				  string: "string"
+			`,
+			APIVersion: "v1",
+			Managed: fieldpath.ManagedFields{
+				"two": fieldpath.NewVersionedSet(
+					_NS(
+						_P("struct"),
+					),
+					"v1",
+					true,
+				),
+			},
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			if err := test.Test(structParser); err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}

typed/typed.go

@@ -71,6 +71,11 @@ func (tv TypedValue) AsValue() value.Value {
 	return tv.value
 }
 
+// Schema removes the schema from the TypedValue.
+func (tv TypedValue) Schema() *schema.Schema {
+	return tv.schema
+}
+
 // Validate returns an error with a list of every spec violation.
 func (tv TypedValue) Validate() error {
 	w := tv.walker()