From 841c1a8ce80cdb24f7763e3520a590aa383f3538 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Olivier=20Mengu=C3=A9?= <dolmen@cpan.org>
Date: Mon, 11 Mar 2024 20:25:41 +0100
Subject: [PATCH] Add fuzzer: FuzzEncodeFromJSON

Add fuzzing for roundtripping by using JSON documents as input
---
 fuzz_test.go | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 fuzz_test.go

diff --git a/fuzz_test.go b/fuzz_test.go
new file mode 100644
index 00000000..89975a4d
--- /dev/null
+++ b/fuzz_test.go
@@ -0,0 +1,74 @@
+//go:build go1.18
+// +build go1.18
+
+package yaml_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"gopkg.in/yaml.v3"
+)
+
+// FuzzEncodeFromJSON checks that any JSON encoded value can also be encoded as YAML... and decoded.
+func FuzzEncodeFromJSON(f *testing.F) {
+	f.Add(`null`)
+	f.Add(`""`)
+	f.Add(`0`)
+	f.Add(`true`)
+	f.Add(`false`)
+	f.Add(`{}`)
+	f.Add(`[]`)
+	f.Add(`[[]]`)
+	f.Add(`{"a":[]}`)
+
+	f.Fuzz(func(t *testing.T, s string) {
+
+		var v interface{}
+		if err := json.Unmarshal([]byte(s), &v); err != nil {
+			t.Skip("not valid JSON")
+		}
+
+		t.Logf("JSON %q", s)
+		t.Logf("Go   %q <%[1]x>", v)
+
+		// Encode as YAML
+		b, err := yaml.Marshal(v)
+		if err != nil {
+			t.Error(err)
+		}
+		t.Logf("YAML %q <%[1]x>", b)
+
+		// Decode as YAML
+		var v2 interface{}
+		if err := yaml.Unmarshal(b, &v2); err != nil {
+			t.Error(err)
+		}
+
+		t.Logf("Go   %q <%[1]x>", v2)
+
+		/*
+			// Handling of number is different, so we can't have universal exact matching
+			if !reflect.DeepEqual(v2, v) {
+				t.Errorf("mismatch:\n-      got: %#v\n- expected: %#v", v2, v)
+			}
+		*/
+
+		b2, err := yaml.Marshal(v2)
+		if err != nil {
+			t.Error(err)
+		}
+		t.Logf("YAML %q <%[1]x>", b2)
+
+		if !bytes.Equal(b, b2) {
+			t.Errorf("Marshal->Unmarshal->Marshal mismatch:\n- expected: %q\n- got:      %q", b, b2)
+		}
+
+	})
+}
+
+func TestEncodeString(t *testing.T) {
+	b, _ := yaml.Marshal(`\n`)
+	t.Logf("%q <%[1]x>", string(b))
+}