From a1943556b41d584fcf5cec89ce7cb31ed4f97316 Mon Sep 17 00:00:00 2001
From: Ruidy <ruidy.nemausat@gmail.com>
Date: Fri, 14 Nov 2025 13:51:35 +0100
Subject: [PATCH] fix: add explicit panic for Max/Min on empty slices
MIME-Version: 1.0
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Adds length checks to Max and Min functions to provide clear,
explicit panic messages when called with empty slices, rather
than allowing confusing index-out-of-bounds panics.

Changes:
- Max: Added check for empty slice with "underscore.Max: empty slice" panic
- Min: Added check for empty slice with "underscore.Min: empty slice" panic
- Updated doc comments to document panic behavior
- Added TestMaxEmpty and TestMinEmpty to verify panic behavior

Impact:
- Better error messages for debugging
- Documented behavior prevents user surprises
- Non-breaking change (still panics, just with clearer message)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 max.go      | 4 ++++
 max_test.go | 6 ++++++
 min.go      | 4 ++++
 min_test.go | 6 ++++++
 4 files changed, 20 insertions(+)

diff --git a/max.go b/max.go
index be74b3c..31957d0 100644
--- a/max.go
+++ b/max.go
@@ -3,9 +3,13 @@ package underscore
 import "cmp"
 
 // Max returns the maximum value in the slice.
+// Panics if values is empty.
 // This function can currently only compare numbers reliably.
 // This function uses operator <.
 func Max[T cmp.Ordered](values []T) T {
+	if len(values) == 0 {
+		panic("underscore.Max: empty slice")
+	}
 	max := values[0]
 	for _, v := range values {
 		if v > max {
diff --git a/max_test.go b/max_test.go
index 5fed20a..1c05cd1 100644
--- a/max_test.go
+++ b/max_test.go
@@ -13,3 +13,9 @@ func TestMax(t *testing.T) {
 	want := 9
 	assert.Equal(t, want, u.Max(nums))
 }
+
+func TestMaxEmpty(t *testing.T) {
+	assert.Panics(t, func() {
+		u.Max([]int{})
+	})
+}
diff --git a/min.go b/min.go
index 35c42a0..1e192c6 100644
--- a/min.go
+++ b/min.go
@@ -3,9 +3,13 @@ package underscore
 import "cmp"
 
 // Min returns the minimum value in the slice.
+// Panics if values is empty.
 // This function can currently only compare numbers reliably.
 // This function uses operator <.
 func Min[T cmp.Ordered](values []T) T {
+	if len(values) == 0 {
+		panic("underscore.Min: empty slice")
+	}
 	min := values[0]
 	for _, v := range values {
 		if v < min {
diff --git a/min_test.go b/min_test.go
index 2b4f6cc..8049bb4 100644
--- a/min_test.go
+++ b/min_test.go
@@ -13,3 +13,9 @@ func TestMin(t *testing.T) {
 	want := 1
 	assert.Equal(t, want, u.Min(nums))
 }
+
+func TestMinEmpty(t *testing.T) {
+	assert.Panics(t, func() {
+		u.Min([]int{})
+	})
+}