Organize test suites into unit and integration

This is the goals of project organization composing different
combinations to run any number of tests together.

tests/integration/TestCase.php

@@ -0,0 +1,54 @@
+<?php
+
+/**
+ * TestCase.php
+ * Copyright (c) 2020 james@firefly-iii.org
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+declare(strict_types=1);
+
+namespace Tests\integration;
+
+use Illuminate\Foundation\Testing\TestCase as BaseTestCase;
+use Tests\integration\Traits\CollectsValues;
+
+/**
+ * Class TestCase
+ */
+abstract class TestCase extends BaseTestCase
+{
+    use CreatesApplication;
+    use CollectsValues;
+
+    protected const MAX_ITERATIONS = 2;
+
+    /**
+     * @return array
+     */
+    public function dateRangeProvider(): array
+    {
+        return [
+            'one day'      => ['1D'],
+            'one week'     => ['1W'],
+            'one month'    => ['1M'],
+            'three months' => ['3M'],
+            'six months'   => ['6M'],
+            'one year'     => ['1Y'],
+            'custom range' => ['custom'],
+        ];
+    }
+}