core/chains/evm/assets: fix FuzzWei range detection (#11950)

core/chains/evm/assets/wei_test.go

@@ -74,10 +74,10 @@ func FuzzWei(f *testing.F) {
 	f.Add("5 micro")
 	f.Fuzz(func(t *testing.T, v string) {
 		if len(v) > 1_000 {
-			t.Skip()
+			t.Skipf("too many characters: %d", len(v))
 		}
-		if tryParseExp(v) > 4888888 {
-			t.Skip()
+		if e := tryParseExp(v); -1000 > e || e > 1000 {
+			t.Skipf("exponent too large: %d", e)
 		}
 		var w Wei
 		err := w.UnmarshalText([]byte(v))
@@ -100,9 +100,30 @@ func tryParseExp(v string) int64 {
 	if i == -1 {
 		return -1
 	}
-	e, err := strconv.ParseInt(v[i+1:], 10, 32)
+	v = v[i+1:]
+	if i := strings.IndexFunc(v, func(r rune) bool {
+		switch {
+		case r == '-' || r == '+':
+			return false
+		case r < '0' || '9' < r:
+			return true
+		}
+		return false
+	}); i > -1 {
+		v = v[:i]
+	}
+	e, err := strconv.ParseInt(v, 10, 32)
 	if err != nil {
 		return -1
 	}
 	return e
 }
+
+func Test_tryParseExp(t *testing.T) {
+	got := tryParseExp("000000000E0000000060000000wei")
+	assert.Equal(t, int64(60000000), got)
+	got = tryParseExp("0e-80000800")
+	assert.Equal(t, int64(-80000800), got)
+	got = tryParseExp("0e+802444440")
+	assert.Equal(t, int64(802444440), got)
+}