underscore/scan_test.go
Ruidy 0bf04c224e
feat: add Scan function (reduce with history) (#43)
- Add Scan: returns all intermediate accumulator values
- Also known as prefix scan or cumulative fold
- Comprehensive tests including edge cases and different types
- Benchmark included

Example: Scan([]int{1,2,3,4}, 0, +) → [1, 3, 6, 10]

Resolves Issue 15

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

Co-authored-by: Claude <noreply@anthropic.com>
2025-11-16 08:53:05 +01:00

68 lines
1.6 KiB
Go

package underscore_test
import (
"testing"
"github.com/stretchr/testify/assert"
u "github.com/rjNemo/underscore"
)
func TestScan(t *testing.T) {
nums := []int{1, 2, 3, 4}
result := u.Scan(nums, 0, func(acc, n int) int { return acc + n })
assert.Equal(t, []int{1, 3, 6, 10}, result)
}
func TestScanEmpty(t *testing.T) {
result := u.Scan([]int{}, 0, func(acc, n int) int { return acc + n })
assert.Equal(t, []int{}, result)
}
func TestScanSingleElement(t *testing.T) {
result := u.Scan([]int{5}, 0, func(acc, n int) int { return acc + n })
assert.Equal(t, []int{5}, result)
}
func TestScanMultiplication(t *testing.T) {
nums := []int{2, 3, 4}
result := u.Scan(nums, 1, func(acc, n int) int { return acc * n })
assert.Equal(t, []int{2, 6, 24}, result)
}
func TestScanStrings(t *testing.T) {
words := []string{"hello", "world", "!"}
result := u.Scan(words, "", func(acc, s string) string { return acc + s })
assert.Equal(t, []string{"hello", "helloworld", "helloworld!"}, result)
}
func TestScanMax(t *testing.T) {
nums := []int{3, 1, 4, 1, 5, 9, 2}
result := u.Scan(nums, 0, func(acc, n int) int {
if n > acc {
return n
}
return acc
})
assert.Equal(t, []int{3, 3, 4, 4, 5, 9, 9}, result)
}
func TestScanDifferentTypes(t *testing.T) {
nums := []int{1, 2, 3}
result := u.Scan(nums, 0.0, func(acc float64, n int) float64 {
return acc + float64(n)*2.5
})
assert.Equal(t, []float64{2.5, 7.5, 15.0}, result)
}
func BenchmarkScan(b *testing.B) {
nums := make([]int, 1000)
for i := range nums {
nums[i] = i
}
b.ResetTimer()
for i := 0; i < b.N; i++ {
u.Scan(nums, 0, func(acc, n int) int { return acc + n })
}
}