From b51a96373503f50594df5c18a07ad6e6a7395517 Mon Sep 17 00:00:00 2001
From: alstephenclaypool <41022275+alstephenclaypool@users.noreply.github.com>
Date: Wed, 20 Sep 2023 19:01:11 -0400
Subject: [PATCH] fix empty yaml on documents with comment only sections (#166)

* fix empty yaml when running vals eval on documents with comment only sections

Signed-off-by: Stephen Claypool <stephen.claypool@homeadvisor.com>

* add tests for nodesFromReader

Signed-off-by: Stephen Claypool <stephen.claypool@homeadvisor.com>

---------

Signed-off-by: Stephen Claypool <stephen.claypool@homeadvisor.com>
---
 io.go      |  4 +++-
 io_test.go | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/io.go b/io.go
index 5e0519e..cf73e89 100644
--- a/io.go
+++ b/io.go
@@ -69,7 +69,9 @@ func nodesFromReader(reader io.Reader) ([]yaml.Node, error) {
 			}
 			break
 		}
-		nodes = append(nodes, node)
+		if len(node.Content[0].Content) > 0 {
+			nodes = append(nodes, node)
+		}
 	}
 	return nodes, nil
 }
diff --git a/io_test.go b/io_test.go
index 2e6d981..9f9e1e0 100644
--- a/io_test.go
+++ b/io_test.go
@@ -77,3 +77,53 @@ func Test_InputOutput(t *testing.T) {
 		})
 	}
 }
+
+func Test_NodesFromReader(t *testing.T) {
+	simpleDocument := "---\nfoo: bar\n"
+	commentDocument := "---\n# comment\n"
+
+	tests := []struct {
+		name  string
+		input string
+		nodes int
+	}{
+		{
+			name:  "single document",
+			input: simpleDocument,
+			nodes: 1,
+		},
+		{
+			name:  "multi document",
+			input: simpleDocument + simpleDocument,
+			nodes: 2,
+		},
+		{
+			name:  "single comment document",
+			input: commentDocument,
+			nodes: 0,
+		},
+		{
+			name:  "multiple comment document",
+			input: commentDocument + commentDocument,
+			nodes: 0,
+		},
+		{
+			name:  "mixed documents",
+			input: simpleDocument + commentDocument,
+			nodes: 1,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			nodes, err := nodesFromReader(strings.NewReader(tt.input))
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if len(nodes) != tt.nodes {
+				t.Errorf("Expected %v nodes, got %v", tt.nodes, len(nodes))
+			}
+		})
+	}
+}