all: Remove lib/util package (#9049)

Grab-bag packages are nasty, this cleans it up a little by splitting it
into topical packages sempahore, netutil, stringutil, structutil.

lib/structutil/structutil_test.go

@@ -0,0 +1,234 @@
+// Copyright (C) 2016 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package structutil
+
+import (
+	"testing"
+)
+
+type Defaulter struct {
+	Value string
+}
+
+func (d *Defaulter) ParseDefault(v string) error {
+	*d = Defaulter{Value: v}
+	return nil
+}
+
+func TestSetDefaults(t *testing.T) {
+	x := &struct {
+		A string    `default:"string"`
+		B int       `default:"2"`
+		C float64   `default:"2.2"`
+		D bool      `default:"true"`
+		E Defaulter `default:"defaulter"`
+	}{}
+
+	if x.A != "" {
+		t.Error("string failed")
+	} else if x.B != 0 {
+		t.Error("int failed")
+	} else if x.C != 0 {
+		t.Errorf("float failed")
+	} else if x.D {
+		t.Errorf("bool failed")
+	} else if x.E.Value != "" {
+		t.Errorf("defaulter failed")
+	}
+
+	SetDefaults(x)
+
+	if x.A != "string" {
+		t.Error("string failed")
+	} else if x.B != 2 {
+		t.Error("int failed")
+	} else if x.C != 2.2 {
+		t.Errorf("float failed")
+	} else if !x.D {
+		t.Errorf("bool failed")
+	} else if x.E.Value != "defaulter" {
+		t.Errorf("defaulter failed")
+	}
+}
+
+func TestFillNillSlices(t *testing.T) {
+	// Nil
+	x := &struct {
+		A []string `default:"a,b"`
+	}{}
+
+	if x.A != nil {
+		t.Error("not nil")
+	}
+
+	if err := FillNilSlices(x); err != nil {
+		t.Error(err)
+	}
+
+	if len(x.A) != 2 {
+		t.Error("length")
+	}
+
+	// Already provided
+	y := &struct {
+		A []string `default:"c,d,e"`
+	}{[]string{"a", "b"}}
+
+	if len(y.A) != 2 {
+		t.Error("length")
+	}
+
+	if err := FillNilSlices(y); err != nil {
+		t.Error(err)
+	}
+
+	if len(y.A) != 2 {
+		t.Error("length")
+	}
+
+	// Non-nil but empty
+	z := &struct {
+		A []string `default:"c,d,e"`
+	}{[]string{}}
+
+	if len(z.A) != 0 {
+		t.Error("length")
+	}
+
+	if err := FillNilSlices(z); err != nil {
+		t.Error(err)
+	}
+
+	if len(z.A) != 0 {
+		t.Error("length")
+	}
+}
+
+func TestFillNil(t *testing.T) {
+	type A struct {
+		Slice []int
+		Map   map[string]string
+		Chan  chan int
+	}
+
+	type B struct {
+		Slice *[]int
+		Map   *map[string]string
+		Chan  *chan int
+	}
+
+	type C struct {
+		A A
+		B *B
+		D *****[]int
+	}
+
+	c := C{}
+	FillNil(&c)
+
+	if c.A.Slice == nil {
+		t.Error("c.A.Slice")
+	}
+	if c.A.Map == nil {
+		t.Error("c.A.Slice")
+	}
+	if c.A.Chan == nil {
+		t.Error("c.A.Chan")
+	}
+	if c.B == nil {
+		t.Error("c.B")
+	}
+	if c.B.Slice == nil {
+		t.Error("c.B.Slice")
+	}
+	if c.B.Map == nil {
+		t.Error("c.B.Slice")
+	}
+	if c.B.Chan == nil {
+		t.Error("c.B.Chan")
+	}
+	if *c.B.Slice == nil {
+		t.Error("*c.B.Slice")
+	}
+	if *c.B.Map == nil {
+		t.Error("*c.B.Slice")
+	}
+	if *c.B.Chan == nil {
+		t.Error("*c.B.Chan")
+	}
+	if *****c.D == nil {
+		t.Error("c.D")
+	}
+}
+
+func TestFillNilDoesNotBulldozeSetFields(t *testing.T) {
+	type A struct {
+		Slice []int
+		Map   map[string]string
+		Chan  chan int
+	}
+
+	type B struct {
+		Slice *[]int
+		Map   *map[string]string
+		Chan  *chan int
+	}
+
+	type C struct {
+		A A
+		B *B
+		D **[]int
+	}
+
+	ch := make(chan int, 10)
+	d := make([]int, 10)
+	dd := &d
+
+	c := C{
+		A: A{
+			Slice: []int{1},
+			Map: map[string]string{
+				"k": "v",
+			},
+			Chan: make(chan int, 10),
+		},
+		B: &B{
+			Slice: &[]int{1},
+			Map: &map[string]string{
+				"k": "v",
+			},
+			Chan: &ch,
+		},
+		D: &dd,
+	}
+	FillNil(&c)
+
+	if len(c.A.Slice) != 1 {
+		t.Error("c.A.Slice")
+	}
+	if len(c.A.Map) != 1 {
+		t.Error("c.A.Slice")
+	}
+	if cap(c.A.Chan) != 10 {
+		t.Error("c.A.Chan")
+	}
+	if c.B == nil {
+		t.Error("c.B")
+	}
+	if len(*c.B.Slice) != 1 {
+		t.Error("c.B.Slice")
+	}
+	if len(*c.B.Map) != 1 {
+		t.Error("c.B.Slice")
+	}
+	if cap(*c.B.Chan) != 10 {
+		t.Error("c.B.Chan")
+	}
+	if cap(**c.D) != 10 {
+		t.Error("c.D")
+	}
+}