detect misuse of !reset tag

Signed-off-by: Nicolas De Loof <[email protected]>

Author: ndeloof

loader/merge_reset_test.go

@@ -0,0 +1,83 @@
+/*
+   Copyright 2020 The Compose Specification 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 loader
+
+import (
+	"context"
+	"testing"
+
+	"github.com/compose-spec/compose-go/v2/types"
+	"gotest.tools/v3/assert"
+)
+
+func Test_LoadWithReset(t *testing.T) {
+	p, err := LoadWithContext(context.TODO(), types.ConfigDetails{
+		ConfigFiles: []types.ConfigFile{
+			{
+				Filename: "base.yml",
+				Content: []byte(`
+ name: test
+ services:
+   foo:
+     build:
+       context: .
+       dockerfile: foo.Dockerfile
+     environment:
+       FOO: BAR`),
+			},
+			{
+				Filename: "override.yml",
+				Content: []byte(`
+ services:
+   foo:
+     image: foo
+     build: !reset  
+     environment:
+       FOO: !reset
+`),
+			},
+		},
+	}, func(options *Options) {
+		options.SkipNormalization = true
+	})
+	assert.NilError(t, err)
+	assert.DeepEqual(t, p.Services["foo"], types.ServiceConfig{
+		Name:        "foo",
+		Image:       "foo",
+		Environment: types.MappingWithEquals{},
+	})
+}
+
+func Test_DuplicateReset(t *testing.T) {
+	_, err := LoadWithContext(context.TODO(), types.ConfigDetails{
+		ConfigFiles: []types.ConfigFile{
+			{
+				Filename: "duplicate.yml",
+				Content: []byte(`
+ name: test
+ services:
+   foo:
+     command: hello
+     command: !reset hello world
+`),
+			},
+		},
+	}, func(options *Options) {
+		options.SkipNormalization = true
+	})
+	assert.Error(t, err, "line 6: mapping key \"command\" already defined at line 5")
+}

loader/reset.go

@@ -67,6 +67,8 @@ func (p *ResetProcessor) resolveReset(node *yaml.Node, path tree.Path) (*yaml.No
 		p.paths = append(p.paths, path)
 		return node, nil
 	}
+
+	keys := map[string]int{}
 	switch node.Kind {
 	case yaml.SequenceNode:
 		var nodes []*yaml.Node
@@ -87,6 +89,10 @@ func (p *ResetProcessor) resolveReset(node *yaml.Node, path tree.Path) (*yaml.No
 		for idx, v := range node.Content {
 			if idx%2 == 0 {
 				key = v.Value
+				if line, seen := keys[key]; seen {
+					return nil, fmt.Errorf("line %d: mapping key %#v already defined at line %d", v.Line, key, line)
+				}
+				keys[key] = v.Line
 			} else {
 				resolved, err := p.resolveReset(v, path.Next(key))
 				if err != nil {