fuzz_test.go

// Copyright 2026 Joshua Jones <joshua.jones.software@gmail.com>
//
// 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 hl7

import "testing"

func FuzzParseMessage(f *testing.F) {
	// Seed corpus with valid messages.
	f.Add([]byte("MSH|^~\\&|SYS|FAC|REC|FAC|202301011200||ADT^A01|123|P|2.5\rPID|||123456||Doe^John\r"))
	f.Add([]byte("MSH|^~\\&|S|F|R|RF|20240101||ORU^R01|1|P|2.5.1\rOBX|1|NM|code||42\r"))
	f.Add([]byte("MSH|^~\\&|S|F|R|RF|20240101||ADT^A01|1|P|2.5.1"))
	f.Add([]byte("MSH|^~\\&||||||||||||"))
	f.Add([]byte("MSH|^~\\&|test\\F\\embed|F|R|RF|20240101||ADT^A01|1|P|2.5.1"))

	f.Fuzz(func(t *testing.T, data []byte) {
		msg, err := ParseMessage(data)
		if err != nil {
			return // Invalid messages are expected.
		}
		// Should not panic on any access pattern.
		for _, seg := range msg.Segments() {
			_ = seg.Type()
			_ = seg.Raw()
			fc := seg.FieldCount()
			for i := 0; i <= fc; i++ {
				f := seg.Field(i)
				_ = f.String()
				_ = f.Bytes()
				_ = f.IsNull()
				_ = f.IsEmpty()
				_ = f.HasValue()
				rc := f.RepetitionCount()
				for j := 0; j < rc && j < 10; j++ {
					r := f.Rep(j)
					_ = r.String()
					cc := r.ComponentCount()
					for k := 1; k <= cc && k <= 10; k++ {
						c := r.Component(k)
						_ = c.String()
						sc := c.SubComponentCount()
						for l := 1; l <= sc && l <= 10; l++ {
							s := c.SubComponent(l)
							_ = s.String()
						}
					}
				}
			}
		}

		// Test accessor.
		_ = msg.Get("MSH-9")
		_ = msg.Get("MSH-9.1")
		_ = msg.Get("PID-3.1.2")
	})
}