lib/ur: Normalise contract between syncthing and ursrv (#6770)

* Fix ui, hide report date

* Undo Goland madness

* UR now web scale

* Fix migration

* Fix marshaling, force tick on start

* Fix tests

* Darwin build

* Split "all" build target, add package name as a tag

* Remove pq and sql dep from syncthing, split build targets

* Empty line

* Revert "Empty line"

This reverts commit f74af2b067.

* Revert "Remove pq and sql dep from syncthing, split build targets"

This reverts commit 8fc295ad00.

* Revert "Split "all" build target, add package name as a tag"

This reverts commit f4dc889951.

* Normalise contract types

* Fix build add more logging

lib/ur/contract/contract_test.go

@@ -0,0 +1,130 @@
+// Copyright (C) 2020 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 contract
+
+import (
+	"reflect"
+	"testing"
+)
+
+type PtrStruct struct {
+	A string         `since:"2"`
+	B map[string]int `since:"3"`
+}
+
+type Nested struct {
+	A float32 `since:"4"`
+	B [4]int  `since:"5"`
+	C bool    `since:"1"`
+}
+
+type TestStruct struct {
+	A      int
+	B      map[string]string `since:"1"`
+	C      []string          `since:"2"`
+	Nested Nested            `since:"3"`
+
+	Ptr *PtrStruct `since:"2"`
+}
+
+func testValue() TestStruct {
+	return TestStruct{
+		A: 1,
+		B: map[string]string{
+			"foo": "bar",
+		},
+		C: []string{"a", "b"},
+		Nested: Nested{
+			A: 0.10,
+			B: [4]int{1, 2, 3, 4},
+			C: true,
+		},
+		Ptr: &PtrStruct{
+			A: "value",
+			B: map[string]int{
+				"x": 1,
+				"b": 2,
+			},
+		},
+	}
+}
+
+func TestClean(t *testing.T) {
+	expect(t, 0, TestStruct{})
+
+	expect(t, 1, TestStruct{
+		// A unset, since it does not have "since"
+		B: map[string]string{
+			"foo": "bar",
+		},
+	})
+
+	expect(t, 2, TestStruct{
+		// A unset, since it does not have "since"
+		B: map[string]string{
+			"foo": "bar",
+		},
+		C: []string{"a", "b"},
+		Ptr: &PtrStruct{
+			A: "value",
+		},
+	})
+
+	expect(t, 3, TestStruct{
+		// A unset, since it does not have "since"
+		B: map[string]string{
+			"foo": "bar",
+		},
+		C: []string{"a", "b"},
+		Nested: Nested{
+			C: true,
+		},
+		Ptr: &PtrStruct{
+			A: "value",
+			B: map[string]int{
+				"x": 1,
+				"b": 2,
+			},
+		},
+	})
+
+	expect(t, 4, TestStruct{
+		// A unset, since it does not have "since"
+		B: map[string]string{
+			"foo": "bar",
+		},
+		C: []string{"a", "b"},
+		Nested: Nested{
+			A: 0.10,
+			C: true,
+		},
+		Ptr: &PtrStruct{
+			A: "value",
+			B: map[string]int{
+				"x": 1,
+				"b": 2,
+			},
+		},
+	})
+
+	x := testValue()
+	x.A = 0
+
+	expect(t, 5, x)
+	expect(t, 6, x)
+}
+
+func expect(t *testing.T, since int, b interface{}) {
+	t.Helper()
+	x := testValue()
+	if err := clear(&x, since); err != nil {
+		t.Fatal(err.Error())
+	}
+	if !reflect.DeepEqual(x, b) {
+		t.Errorf("%#v != %#v", x, b)
+	}
+}