tests: add fuzzing

cmdscale · Oct 17, 2024 · 4b773fc · 4b773fc
1 parent 4dc6ced
commit 4b773fc
Show file tree

Hide file tree

Showing 3 changed files with 87 additions and 5 deletions.
diff --git a/Makefile b/Makefile
@@ -17,6 +17,5 @@ test-license:
 	reuse lint
 
 fuzz:
-	go test -fuzztime=10s -fuzz=NewIBAN
-	go test -fuzztime=10s -fuzz=NewBIC
-	go test -fuzztime=10s -fuzz=FromIBAN ./bic
+	go test -fuzztime=10s -fuzz=NewISIN
+	go test -fuzztime=10s -fuzz=GenerateISIN
diff --git a/isin.go b/isin.go
@@ -26,7 +26,7 @@ func NewISIN(s string, additionalRules ...ISINValidator) (ISIN, error) {
 	isin.NSIN = s[2:11]
 	isin.CheckDigit = int(s[11] - '0')
 	if isin.CheckDigit < 0 || isin.CheckDigit > 9 {
-		return isin, CheckDigitError{Given: isin.CheckDigit}
+		return isin, CheckDigitError{Given: isin.CheckDigit, Computed: -1}
 	}
 	c := isin.checkDigit()
 	if c != isin.CheckDigit {
@@ -113,6 +113,6 @@ func (e CheckDigitError) Error() string {
 	if e.Given < 0 || e.Given > 9 {
 		return "expected digit as last chart, got " + strconv.Quote(string(byte(e.Given+'0')))
 	}
-	// don't display the expected/actual digits, because the error is most likely somewhere else in the BBAN
+	// don't display the expected/actual digits, because the error is most likely somewhere else in the NSIN
 	return "wrong check digit"
 }
diff --git a/isin_test.go b/isin_test.go
@@ -6,6 +6,7 @@ package corfin
 
 import (
 	"errors"
+	"strconv"
 	"testing"
 
 	"code.pfad.fr/check"
@@ -113,3 +114,85 @@ func TestInvalidISIN(t *testing.T) {
 		f("GB0002634947", 7, 6)
 	})
 }
+
+func FuzzNewISIN(f *testing.F) {
+	f.Add("US0378331005")
+	f.Add("DE0006231004")
+	f.Add("DE000BAY0017")
+	f.Add("XF0000C14922")
+	f.Add("NL0000729408")
+	f.Add("CH0031240127")
+	f.Add("US5949181045")
+	f.Add("US38259P5089")
+	f.Add("JP3946600008")
+	f.Add("DE000DZ21632")
+	f.Add("DE000DB7HWY7")
+	f.Add("DE000CM7VX13")
+	f.Add("CH0031240127")
+	f.Add("CA9861913023")
+	f.Fuzz(func(t *testing.T, s string) {
+		isin, err := NewISIN(s)
+		if err != nil {
+			var cerr CheckDigitError
+			var lerr LenError
+			if errors.As(err, &cerr) || errors.As(err, &lerr) {
+				return
+			}
+			t.Fatal(err)
+		}
+		isin2, err := NewISIN(isin.String())
+		check.Equal(t, nil, err).Fatal()
+		check.Equal(t, isin, isin2)
+	})
+}
+
+func FuzzGenerateISIN(f *testing.F) {
+	f.Add("US0378331005")
+	f.Add("DE0006231004")
+	f.Add("DE000BAY0017")
+	f.Add("XF0000C14922")
+	f.Add("NL0000729408")
+	f.Add("CH0031240127")
+	f.Add("US5949181045")
+	f.Add("US38259P5089")
+	f.Add("JP3946600008")
+	f.Add("DE000DZ21632")
+	f.Add("DE000DB7HWY7")
+	f.Add("DE000CM7VX13")
+	f.Add("CH0031240127")
+	f.Add("CA9861913023")
+	// wrong isins:
+	f.Add("CA9861913024")   // will be fixed
+	f.Add("CA9861913024 ")  // will be fixed
+	f.Add("CA986191302A")   // not fixable: last char is not a digit
+	f.Add("CA9861913024BC") // not fixable: too long
+	f.Fuzz(func(t *testing.T, s string) {
+		isin, err := NewISIN(s)
+		if err == nil {
+			return
+		}
+		var lerr LenError
+		if errors.As(err, &lerr) {
+			// hard to fix
+			return
+		}
+		var cerr CheckDigitError
+		if !errors.As(err, &cerr) {
+			t.Fatal(err)
+		}
+		if cerr.Computed == -1 {
+			// last char is not a digit: not fixable
+			return
+		}
+		// fix the check digit
+		t.Log("before", s, cerr.Given)
+		t.Log("after", isin.String())
+		s = isin.String() // get the cleaned version
+		s = s[:len(s)-1] + strconv.Itoa(cerr.Computed)
+		isin, err = NewISIN(s)
+		if err != nil {
+			t.Fatal(err)
+		}
+		check.Equal(t, isin.String(), s)
+	})
+}