From 7e28b012640d3fe2251fb306c6e31eb82c7d24b9 Mon Sep 17 00:00:00 2001
From: Markus Sommer <msommer@informatik.uni-marburg.de>
Date: Fri, 5 Apr 2024 20:45:15 +0200
Subject: [PATCH] Property-based tests for majors & strings

As a bonus, this gets rid of `math/rand` and the associated `golangci-lint` complaint
---
 go.mod          |  4 ++++
 go.sum          |  2 ++
 major_test.go   | 31 ++++++++++++++++++++-----------
 strings_test.go | 26 +++++++++++---------------
 4 files changed, 37 insertions(+), 26 deletions(-)
 create mode 100644 go.sum

diff --git a/go.mod b/go.mod
index 6d53ef0..c5450b1 100644
--- a/go.mod
+++ b/go.mod
@@ -1 +1,5 @@
 module github.com/dtn7/cboring
+
+go 1.22
+
+require pgregory.net/rapid v1.1.0
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..09120c6
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+pgregory.net/rapid v1.1.0 h1:CMa0sjHSru3puNx+J0MIAuiiEV4N0qj8/cMWGBBCsjw=
+pgregory.net/rapid v1.1.0/go.mod h1:PY5XlDGj0+V1FCq0o192FdRhpKHGTRIWBgqjDBTrq04=
diff --git a/major_test.go b/major_test.go
index 1669ba3..e2b1e6e 100644
--- a/major_test.go
+++ b/major_test.go
@@ -3,9 +3,10 @@ package cboring
 import (
 	"bufio"
 	"bytes"
-	"math/rand"
 	"reflect"
 	"testing"
+
+	"pgregory.net/rapid"
 )
 
 func TestReadMajorsSmall(t *testing.T) {
@@ -166,14 +167,17 @@ func TestReadExampleArray(t *testing.T) {
 	}
 }
 
-func TestReadBigData(t *testing.T) {
-	var size = 1024
-	var payload = make([]byte, size)
-	rand.Seed(0)
-	rand.Read(payload)
+const (
+	dataMinSize  = 0
+	dataMaxSize  = 1024
+	dataMinElems = 0
+	dataMaxElems = 50000
+)
 
-	var elems = []int{100, 500, 1000, 5000, 10000, 50000}
-	for _, elem := range elems {
+func TestReadBigData(t *testing.T) {
+	rapid.Check(t, func(t *rapid.T) {
+		payload := rapid.SliceOfN(rapid.Byte(), dataMinSize, dataMaxSize).Draw(t, "Payload")
+		elem := rapid.IntRange(dataMinElems, dataMaxElems).Draw(t, "Elements")
 		buff := new(bytes.Buffer)
 		bw := bufio.NewWriter(buff)
 
@@ -192,9 +196,14 @@ func TestReadBigData(t *testing.T) {
 			tmp, err := ReadByteString(br)
 			if err != nil {
 				t.Fatalf("Reading no %d errored: %v", i, err)
-			} else if len(tmp) != size {
-				t.Fatalf("Length no %d mismatches: %d != %d", i, len(tmp), size)
+			} else if len(tmp) != len(payload) {
+				t.Fatalf("Length no %d mismatches: %d != %d", i, len(tmp), len(payload))
+			}
+			for j := 0; j < len(tmp); j++ {
+				if tmp[j] != payload[j] {
+					t.Fatalf("Wrong value at %d: %d != %d", i, j, len(tmp))
+				}
 			}
 		}
-	}
+	})
 }
diff --git a/strings_test.go b/strings_test.go
index cec09dc..5f93421 100644
--- a/strings_test.go
+++ b/strings_test.go
@@ -3,9 +3,10 @@ package cboring
 import (
 	"bytes"
 	"fmt"
-	"math/rand"
 	"reflect"
 	"testing"
+
+	"pgregory.net/rapid"
 )
 
 func TestByteString(t *testing.T) {
@@ -44,20 +45,15 @@ func TestByteString(t *testing.T) {
 	}
 }
 
-func BenchmarkByteString(b *testing.B) {
-	sizes := []int{
-		// Ridiculously small
-		0, 1, 128, 256,
-		// Kibibytes
-		1024, 10240, 102400,
-		// Mebibytes
-		1048576, 10485760, 104857600,
-	}
+const (
+	stringsMinSize = 0
+	stringMaxSize  = 104857600
+)
 
-	for _, size := range sizes {
-		rndData := make([]byte, size)
-		rand.Seed(0)
-		rand.Read(rndData)
+func BenchmarkByteString(b *testing.B) {
+	rapid.Check(b, func(t *rapid.T) {
+		rndData := rapid.SliceOfN(rapid.Byte(), stringsMinSize, stringMaxSize).Draw(t, "rndData")
+		size := len(rndData)
 
 		b.Run(fmt.Sprintf("%d", size), func(b *testing.B) {
 			for i := 0; i < b.N; i++ {
@@ -87,7 +83,7 @@ func BenchmarkByteString(b *testing.B) {
 				}
 			}
 		})
-	}
+	})
 }
 
 func TestReadTextString(t *testing.T) {