From db76742519a9168741302b16d7d1070ce8b4470e Mon Sep 17 00:00:00 2001
From: samricotta <samanthalricotta@gmail.com>
Date: Wed, 31 Jul 2024 17:44:03 +0200
Subject: [PATCH] updates on using scientific notation

(cherry picked from commit 7ede82f79bab5eb13da8dc02ef80ef90112a521f)
---
 math/dec.go      | 17 ++++++--------
 math/dec_test.go | 61 +++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 54 insertions(+), 24 deletions(-)

diff --git a/math/dec.go b/math/dec.go
index 13f72513a6ff..86d5f279e214 100644
--- a/math/dec.go
+++ b/math/dec.go
@@ -381,19 +381,16 @@ func (x Dec) Marshal() ([]byte, error) {
 // Unmarshal parses a byte slice containing a text-formatted decimal and stores the result in the receiver.
 // It returns an error if the byte slice does not represent a valid decimal.
 func (x *Dec) Unmarshal(data []byte) error {
-	var d apd.Decimal
-	_, _, err := d.SetString(string(data))
+	result, err := NewDecFromString(string(data))
 	if err != nil {
 		return ErrInvalidDec.Wrap(err.Error())
 	}
 
-	switch d.Form {
-	case apd.NaN, apd.NaNSignaling:
-		return ErrInvalidDec.Wrap("not a number")
-	case apd.Infinite:
-		return ErrInvalidDec.Wrap("infinite decimal value not allowed")
-	default:
-		x.dec = d
-		return nil
+	if result.dec.Form != apd.Finite {
+		return ErrInvalidDec.Wrap("unknown decimal form")
 	}
+
+	x.dec = result.dec
+	return nil
+
 }
diff --git a/math/dec_test.go b/math/dec_test.go
index 6f084bced476..cb53b749e3c1 100644
--- a/math/dec_test.go
+++ b/math/dec_test.go
@@ -7,6 +7,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/cockroachdb/apd/v3"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -1325,6 +1326,14 @@ func TestMarshal(t *testing.T) {
 			x:   must(NewDecFromString("-1." + strings.Repeat("0", 34))),
 			exp: "-1.0000000000000000000000000000000000",
 		},
+		"6 decimal places": {
+			x:   must(NewDecFromString("0.000001")),
+			exp: "0.000001",
+		},
+		"7 decimal places": {
+			x:   must(NewDecFromString("0.0000001")),
+			exp: "1E-7",
+		},
 		"1e100000": {
 			x:   NewDecWithPrec(1, 100_000),
 			exp: "1E+100000",
@@ -1353,13 +1362,13 @@ func TestUnMarshal(t *testing.T) {
 		exp    string
 		expErr error
 	}{
-		"No trailing zeros": {
-			x:   "123456",
+		"Leading zeros": {
+			x:   "000123456",
 			exp: "123456",
 		},
 		"Trailing zeros": {
-			x:   "1.23456E+8",
-			exp: "123456000",
+			x:   "1.00000",
+			exp: "1.00000",
 		},
 		"Small e": {
 			x:   "1.23456e+8",
@@ -1369,6 +1378,10 @@ func TestUnMarshal(t *testing.T) {
 			x:   "0",
 			exp: "0",
 		},
+		"-0": {
+			x:   "-0",
+			exp: "-0",
+		},
 		"Decimal value": {
 			x:   "1.3000",
 			exp: "1.3000",
@@ -1381,13 +1394,21 @@ func TestUnMarshal(t *testing.T) {
 			x:   "-1E+1",
 			exp: "-10",
 		},
-		"max decimal": {
-			x:   "9",
-			exp: "9",
+		"Max Exponent": {
+			x:   "1e" + strconv.Itoa(apd.MaxExponent),
+			exp: "1e" + strconv.Itoa(apd.MaxExponent),
 		},
-		"min decimal": {
-			x:   "-1",
-			exp: "-1",
+		"Above Max Exponent": {
+			x:      "1e" + strconv.Itoa(apd.MaxExponent+1),
+			expErr: ErrInvalidDec,
+		},
+		"Min Exponent": {
+			x:   "1e-100000",
+			exp: "1e-100000",
+		},
+		"Below Min Exponent": {
+			x:      "1e" + strconv.Itoa(apd.MinExponent-1),
+			expErr: ErrInvalidDec,
 		},
 		"1e100000": {
 			x:   "1E+100000",
@@ -1417,6 +1438,18 @@ func TestUnMarshal(t *testing.T) {
 			x:      "1foo",
 			expErr: ErrInvalidDec,
 		},
+		".": {
+			x:      ".",
+			expErr: ErrInvalidDec,
+		},
+		"0.": {
+			x:   "0.",
+			exp: "0",
+		},
+		".0": {
+			x:   ".0",
+			exp: "0.0",
+		},
 	}
 	for name, spec := range specs {
 		t.Run(name, func(t *testing.T) {
@@ -1426,12 +1459,12 @@ func TestUnMarshal(t *testing.T) {
 				require.ErrorIs(t, err, spec.expErr)
 				return
 			}
-			if unmarshaled.dec.Exponent == 100000 {
-				coeffStr := unmarshaled.dec.Coeff.String()
+			if unmarshaled.dec.Exponent == 100000 || unmarshaled.dec.Exponent == -100000 {
 				if unmarshaled.dec.Negative {
-					coeffStr = "-" + coeffStr
+					assert.Equal(t, spec.exp, "-"+unmarshaled.dec.Coeff.String()+"e"+strconv.Itoa(int(unmarshaled.dec.Exponent)))
+				} else {
+					assert.Equal(t, spec.exp, unmarshaled.dec.Coeff.String()+"e"+strconv.Itoa(int(unmarshaled.dec.Exponent)))
 				}
-				assert.Equal(t, spec.exp, coeffStr+"e"+strconv.Itoa(int(unmarshaled.dec.Exponent)))
 			} else {
 				assert.Equal(t, spec.exp, unmarshaled.String())
 			}