Fix slice string format with min and max int

Suppress the min and max when set with a negative step. Prevents
aggressive display of large numbers not specified by the user.

CHANGELOG.md

@@ -7,6 +7,15 @@ All notable changes to this project will be documented in this file. It uses the
   [Semantic Versioning]: https://semver.org/spec/v2.0.0.html
     "Semantic Versioning 2.0.0"
 
+## [v0.2.1 ] — Unreleased
+
+### 🪲 Bug Fixes
+
+*   Fixed the formatting of slice strings to omit min and max integers when
+    not specified and using a negative step.
+
+  [v0.2.1]: https://github.com/theory/jsonpath/compare/v0.2.0...v0.2.1
+
 ## [v0.2.0] — 2024-11-13
 
 ### ⚡ Improvements

spec/selector.go

@@ -194,11 +194,11 @@ func Slice(args ...any) SliceSelector {
 
 // writeTo writes a string representation of s to buf.
 func (s SliceSelector) writeTo(buf *strings.Builder) {
-	if s.start != 0 {
+	if s.start != 0 && (s.step >= 0 || s.start != math.MaxInt) {
 		buf.WriteString(strconv.FormatInt(int64(s.start), 10))
 	}
 	buf.WriteByte(':')
-	if s.end != math.MaxInt {
+	if s.end != math.MaxInt && (s.step >= 0 || s.end != math.MinInt) {
 		buf.WriteString(strconv.FormatInt(int64(s.end), 10))
 	}
 	if s.step != 1 {

spec/selector_test.go

@@ -1,6 +1,7 @@
 package spec
 
 import (
+	"fmt"
 	"math"
 	"strings"
 	"testing"
@@ -127,6 +128,51 @@ func TestSelectorString(t *testing.T) {
 			tok:  Slice(nil, nil, 3),
 			str:  "::3",
 		},
+		{
+			name: "slice_neg_step",
+			tok:  Slice(nil, nil, -1),
+			str:  "::-1",
+		},
+		{
+			name: "slice_max_start",
+			tok:  Slice(math.MaxInt),
+			str:  fmt.Sprintf("%v:", math.MaxInt),
+		},
+		{
+			name: "slice_max_start_neg_step",
+			tok:  Slice(math.MaxInt, nil, -1),
+			str:  "::-1",
+		},
+		{
+			name: "slice_min_start",
+			tok:  Slice(math.MinInt),
+			str:  fmt.Sprintf("%v:", math.MinInt),
+		},
+		{
+			name: "slice_min_start_neg_step",
+			tok:  Slice(math.MinInt, nil, -1),
+			str:  fmt.Sprintf("%v::-1", math.MinInt),
+		},
+		{
+			name: "slice_max_end",
+			tok:  Slice(0, math.MaxInt),
+			str:  ":",
+		},
+		{
+			name: "slice_max_end_neg_step",
+			tok:  Slice(0, math.MaxInt, -1),
+			str:  "::-1",
+		},
+		{
+			name: "slice_min_end",
+			tok:  Slice(0, math.MinInt),
+			str:  fmt.Sprintf(":%v", math.MinInt),
+		},
+		{
+			name: "slice_min_end_neg_step",
+			tok:  Slice(0, math.MinInt, -1),
+			str:  "::-1",
+		},
 		{
 			name: "wildcard",
 			tok:  Wildcard,