Initial commit of modash

This was taken from github.com/lmika/gopkgs/fp

moslice/map_test.go

@@ -0,0 +1,58 @@
+package moslice_test
+
+import (
+	"errors"
+	"lmika.dev/pkg/modash/moslice"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMap(t *testing.T) {
+	t.Run("should return a mapped slice", func(t *testing.T) {
+		ts := []int{1, 2, 3}
+		us := moslice.Map(ts, func(x int) int { return x + 2 })
+
+		assert.Equal(t, []int{3, 4, 5}, us)
+	})
+
+	t.Run("should return nil if passed in nil", func(t *testing.T) {
+		ts := []int(nil)
+		us := moslice.Map(ts, func(x int) int { return x + 2 })
+
+		assert.Nil(t, us)
+	})
+}
+
+func TestMapWithError(t *testing.T) {
+	t.Run("should return a mapped slice with no error", func(t *testing.T) {
+		ts := []int{1, 2, 3}
+
+		us, err := moslice.MapWithError(ts, func(x int) (int, error) { return x + 2, nil })
+
+		assert.Equal(t, []int{3, 4, 5}, us)
+		assert.NoError(t, err)
+	})
+
+	t.Run("should return nil with an error when mapping function returns an error", func(t *testing.T) {
+		ts := []int{1, 2, 3}
+
+		us, err := moslice.MapWithError(ts, func(x int) (int, error) {
+			if x == 2 {
+				return 0, errors.New("bang")
+			}
+			return x + 2, nil
+		})
+
+		assert.Nil(t, us)
+		assert.Error(t, err)
+	})
+
+	t.Run("should return nil if passed in nil", func(t *testing.T) {
+		ts := []int(nil)
+		us, err := moslice.MapWithError(ts, func(x int) (int, error) { return x + 2, nil })
+
+		assert.Nil(t, us)
+		assert.NoError(t, err)
+	})
+}