From 9864afc4e7ca6ae6d40dcbac401e3d167b91b8e5 Mon Sep 17 00:00:00 2001
From: Mike Farah <mikefarah@gmail.com>
Date: Thu, 13 Feb 2020 18:08:13 +1100
Subject: [PATCH] Fixed empty merge problem

---
 cmd/commands_test.go        | 21 ++++++++++++++++++++-
 pkg/yqlib/data_navigator.go |  4 ++--
 pkg/yqlib/lib.go            | 27 +++++++++++++++++++++++----
 3 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/cmd/commands_test.go b/cmd/commands_test.go
index 4230e6da..d66ef87b 100644
--- a/cmd/commands_test.go
+++ b/cmd/commands_test.go
@@ -1581,7 +1581,7 @@ func TestWriteCmd_SplatMapEmpty(t *testing.T) {
 		t.Error(result.Error)
 	}
 	expectedOutput := `b:
-  c: thing
+  c: {}
   d: another thing
 `
 	test.AssertResult(t, expectedOutput, result.Output)
@@ -2009,6 +2009,25 @@ apples: red
 	test.AssertResult(t, expectedOutput, result.Output)
 }
 
+func TestMergeYamlNullMapCmd(t *testing.T) {
+	content := `b:`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	mergeContent := `b:
+  thing: a frog
+`
+	mergeFilename := test.WriteTempYamlFile(mergeContent)
+	defer test.RemoveTempYamlFile(mergeFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge %s %s", filename, mergeFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	test.AssertResult(t, mergeContent, result.Output)
+}
+
 func TestMergeCmd_Error(t *testing.T) {
 	cmd := getRootCommand()
 	result := test.RunCmd(cmd, "merge")
diff --git a/pkg/yqlib/data_navigator.go b/pkg/yqlib/data_navigator.go
index a05d10ba..b0e0a28a 100644
--- a/pkg/yqlib/data_navigator.go
+++ b/pkg/yqlib/data_navigator.go
@@ -60,7 +60,7 @@ func (n *navigator) doTraverse(value *yaml.Node, head interface{}, tail []interf
 
 func (n *navigator) getOrReplace(original *yaml.Node, expectedKind yaml.Kind) *yaml.Node {
 	if original.Kind != expectedKind {
-		log.Debug("wanted %v but it was %v, overriding", expectedKind, original.Kind)
+		log.Debug("wanted %v but it was %v, overriding", KindString(expectedKind), KindString(original.Kind))
 		return &yaml.Node{Kind: expectedKind}
 	}
 	return original
@@ -113,7 +113,7 @@ func (n *navigator) recurseMap(value *yaml.Node, head string, tail []interface{}
 		if n.navigationStrategy.ShouldTraverse(NewNodeContext(contents[indexInMap+1], head, tail, newPathStack), contents[indexInMap].Value) {
 			log.Debug("recurseMap: Going to traverse")
 			traversedEntry = true
-			// contents[indexInMap+1] = n.getOrReplace(contents[indexInMap+1], guessKind(head, tail, contents[indexInMap+1].Kind))
+			contents[indexInMap+1] = n.getOrReplace(contents[indexInMap+1], guessKind(head, tail, contents[indexInMap+1].Kind))
 			errorTraversing := n.doTraverse(contents[indexInMap+1], head, tail, newPathStack)
 			log.Debug("recurseMap: Finished traversing")
 			n.navigationStrategy.DebugVisitedNodes()
diff --git a/pkg/yqlib/lib.go b/pkg/yqlib/lib.go
index 667371a6..0cba90df 100644
--- a/pkg/yqlib/lib.go
+++ b/pkg/yqlib/lib.go
@@ -19,6 +19,23 @@ type UpdateCommand struct {
 	Overwrite bool
 }
 
+func KindString(kind yaml.Kind) string {
+	switch kind {
+	case yaml.ScalarNode:
+		return "ScalarNode"
+	case yaml.SequenceNode:
+		return "SequenceNode"
+	case yaml.MappingNode:
+		return "MappingNode"
+	case yaml.DocumentNode:
+		return "DocumentNode"
+	case yaml.AliasNode:
+		return "AliasNode"
+	default:
+		return "unknown!"
+	}
+}
+
 func DebugNode(value *yaml.Node) {
 	if value == nil {
 		log.Debug("-- node is nil --")
@@ -30,7 +47,7 @@ func DebugNode(value *yaml.Node) {
 			log.Error("Error debugging node, %v", errorEncoding.Error())
 		}
 		encoder.Close()
-		log.Debug("Tag: %v", value.Tag)
+		log.Debug("Tag: %v, Kind: %v", value.Tag, KindString(value.Kind))
 		log.Debug("%v", buf.String())
 	}
 }
@@ -91,12 +108,14 @@ func guessKind(head interface{}, tail []interface{}, guess yaml.Kind) yaml.Kind
 			return yaml.SequenceNode
 		}
 		pathParser := NewPathParser()
-		if (pathParser.IsPathExpression(nextString) || head == "**") && (guess == yaml.SequenceNode || guess == yaml.MappingNode) {
+		if pathParser.IsPathExpression(nextString) && (guess == yaml.SequenceNode || guess == yaml.MappingNode) {
 			return guess
-		}
-		if guess == yaml.AliasNode {
+		} else if guess == yaml.AliasNode {
 			log.Debug("guess was an alias, okey doke.")
 			return guess
+		} else if head == "**" {
+			log.Debug("deep wildcard, go with the guess")
+			return guess
 		}
 		log.Debug("forcing a mapping node")
 		log.Debug("yaml.SequenceNode %v", guess == yaml.SequenceNode)