Merge pull request #76 from Teamwork/enhancement/default

Enhancement: `Default`

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Lint
         uses: golangci/golangci-lint-action@v3
@@ -19,7 +19,7 @@ jobs:
     env:
       GORACE: history_size=4
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Set up Go
         uses: actions/setup-go@v4

goutil/goutil_test.go

@@ -90,6 +90,7 @@ func TestExpand(t *testing.T) {
 				"github.com/teamwork/utils/v2/stringutil",
 				"github.com/teamwork/utils/v2/syncutil",
 				"github.com/teamwork/utils/v2/timeutil",
+				"github.com/teamwork/utils/v2/typeutil",
 			},
 			"",
 		},

ioutilx/copy_test.go

@@ -298,7 +298,7 @@ func TestCopyTree(t *testing.T) {
 	})
 	t.Run("permission", func(t *testing.T) {
 		err := CopyTree("test", "/cant/write/here", nil)
-		if !test.ErrorContains(err, "permission denied") {
+		if !test.ErrorContains(err, "permission denied") && !test.ErrorContains(err, "read-only file system") {
 			t.Error(err)
 		}
 	})

typeutil/typeutil.go

@@ -0,0 +1,15 @@
+// Package typeutil adds functions for types.
+package typeutil // import "github.com/teamwork/utils/v2/typeutil"
+
+// Default returns `val` if it is not zero, otherwise returns
+// `def`.
+//
+// v := Default("", "hello")      // return "hello"
+// v := Default("world", "hello") // return "world"
+func Default[T comparable](val, def T) T {
+	if val == *new(T) {
+		return def
+	}
+
+	return val
+}

typeutil/typeutil_test.go

@@ -0,0 +1,34 @@
+package typeutil_test
+
+import (
+	"testing"
+
+	"github.com/teamwork/utils/v2/typeutil"
+)
+
+func Test_Default(t *testing.T) {
+	tests := map[string]struct {
+		in  string
+		exp string
+	}{
+		"empty string returns default": {
+			in:  "",
+			exp: "default value",
+		},
+		"non-empty string returns value": {
+			in:  "hello there",
+			exp: "hello there",
+		},
+	}
+
+	for name, test := range tests {
+		test := test
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			if val := typeutil.Default(test.in, "default value"); val != test.exp {
+				t.Fatalf("expected '%s', got '%s'", test.exp, val)
+			}
+		})
+	}
+}