🧹 Add basic string slice intersection fn (#1137)

stringx/intersection.go

@@ -0,0 +1,17 @@
+package stringx
+
+func Intersection(a, b []string) []string {
+	entriesMap := map[string]struct{}{}
+	res := []string{}
+
+	for i := range a {
+		entriesMap[a[i]] = struct{}{}
+	}
+
+	for i := range b {
+		if _, ok := entriesMap[b[i]]; ok {
+			res = append(res, b[i])
+		}
+	}
+	return res
+}

stringx/intersection_test.go

@@ -0,0 +1,24 @@
+package stringx
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIntersection(t *testing.T) {
+	a := []string{"a", "b", "c"}
+	b := []string{"b", "c", "d", "f"}
+
+	actual := Intersection(a, b)
+	expected := []string{"b", "c"}
+	assert.ElementsMatch(t, actual, expected)
+}
+
+func TestIntersectionNoOverlap(t *testing.T) {
+	a := []string{"a", "b", "c"}
+	b := []string{"d", "f"}
+
+	actual := Intersection(a, b)
+	assert.Empty(t, actual)
+}