dep: add TestCalculatePrune

Add a test for dep.calculatePrune

Signed-off-by: Ibrahim AshShohail <[email protected]>

Author: ibrasho

txn_writer_test.go

@@ -8,9 +8,12 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
 	"testing"
 
+	"reflect"
+
 	"github.com/golang/dep/internal/test"
 	"github.com/pkg/errors"
 )
@@ -567,3 +570,37 @@ func TestSafeWriter_VendorDotGitPreservedWithForceVendor(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestCalculatePrune(t *testing.T) {
+	h := test.NewHelper(t)
+	defer h.Cleanup()
+
+	vendorDir := "vendor"
+	h.TempDir(vendorDir)
+	h.TempDir(filepath.Join(vendorDir, "github.com", "prune", "package"))
+	h.TempDir(filepath.Join(vendorDir, "github.com", "keep", "package"))
+
+	toKeep := []string{
+		"github.com/keep/package",
+	}
+
+	got, err := calculatePrune(h.Path(vendorDir), toKeep, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	sort.Sort(byLen(got))
+
+	if len(got) != 2 {
+		t.Fatalf("expected 2 directories, got %v", len(got))
+	}
+
+	want := []string{
+		h.Path(filepath.Join(vendorDir, "github.com", "prune", "package")),
+		h.Path(filepath.Join(vendorDir, "github.com", "prune")),
+	}
+
+	if !reflect.DeepEqual(want, got) {
+		t.Fatalf("expect %s, got %s", want, got)
+	}
+}