PLT-6112: Add some more unit tests to the model package (#6142)

* Unit Tests for model/push_response.go

* Unit tests for security_bulletin.go

* Unit tests for webrtc.go

* Unit tests for model/password_recovery.go

* Add missing headers.

* Unit tests for model/license.go

* Tidy up existing tests.

* Simplify JSON to/from tests.

* Fix gofmt

model/security_bulletin_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2017 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package model
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestSecurityBulletinToFromJson(t *testing.T) {
+	b := SecurityBulletin{
+		Id:               NewId(),
+		AppliesToVersion: NewId(),
+	}
+
+	j := b.ToJson()
+	b1 := SecurityBulletinFromJson(strings.NewReader(j))
+
+	CheckString(t, b1.AppliesToVersion, b.AppliesToVersion)
+	CheckString(t, b1.Id, b.Id)
+
+	// Malformed JSON
+	s2 := `{"wat"`
+	b2 := SecurityBulletinFromJson(strings.NewReader(s2))
+
+	if b2 != nil {
+		t.Fatal("expected nil")
+	}
+}
+
+func TestSecurityBulletinsToFromJson(t *testing.T) {
+	b := SecurityBulletins{
+		{
+			Id:               NewId(),
+			AppliesToVersion: NewId(),
+		},
+		{
+			Id:               NewId(),
+			AppliesToVersion: NewId(),
+		},
+	}
+
+	j := b.ToJson()
+
+	b1 := SecurityBulletinsFromJson(strings.NewReader(j))
+
+	CheckInt(t, len(b1), 2)
+
+	// Malformed JSON
+	s2 := `{"wat"`
+	b2 := SecurityBulletinsFromJson(strings.NewReader(s2))
+
+	CheckInt(t, len(b2), 0)
+}