Add basic tests for DiffSect function

diffsect_test.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDiffSect(t *testing.T) {
+	tests := []struct {
+		a      []string
+		b      []string
+		c      []string
+		result []string
+	}{
+		{
+			a:      []string{"1", "2", "3"},
+			b:      []string{"1", "2", "3", "4", "5", "6"},
+			c:      []string{"1", "2", "3", "4", "5", "6", "7", "8", "9"},
+			result: []string{"4", "5", "6"},
+		},
+		{
+			a:      []string{"1", "2", "3"},
+			b:      []string{"1", "2", "4", "5", "6"},
+			c:      []string{"1", "5", "6", "7", "8", "9"},
+			result: []string{"5", "6"},
+		},
+	}
+
+	for _, pair := range tests {
+		result := DiffSect(&pair.a, &pair.b, &pair.c)
+		assert.Equal(t, *result, pair.result)
+	}
+}