Add classes and tests from common project

tests/unit/Query/CountTest.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types=1);
+
+namespace Test\Unit\Query;
+
+use BitBadger\PDODocument\Field;
+use BitBadger\PDODocument\Query\Count;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Unit tests for the Count class
+ */
+class CountTest extends TestCase
+{
+
+    public function testAllSucceeds()
+    {
+        $this->assertEquals('SELECT COUNT(*) FROM a_table', Count::all('a_table'),
+            'SELECT statement not generated correctly');
+    }
+
+    public function testByFieldsSucceeds()
+    {
+        $this->assertEquals("SELECT COUNT(*) FROM somewhere WHERE data->>'errors' > @errors",
+            Count::byFields('somewhere', [Field::GT('errors', 10, '@errors')]));
+    }
+}