added skip clause tests

Author: transistive

src/Clauses/SkipClause.php

@@ -35,7 +35,7 @@ class SkipClause extends Clause
      *
      * @var NumeralType|null $skip
      */
-    private ?NumeralType $skip;
+    private ?NumeralType $skip = null;
 
     /**
      * Sets the expression that returns the skip.

tests/Unit/Clauses/SkipClauseTest.php

@@ -0,0 +1,82 @@
+<?php
+
+/*
+ * Cypher DSL
+ * Copyright (C) 2021  Wikibase Solutions
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+namespace WikibaseSolutions\CypherDSL\Tests\Unit\Clauses;
+
+use PHPUnit\Framework\TestCase;
+use TypeError;
+use WikibaseSolutions\CypherDSL\Clauses\LimitClause;
+use WikibaseSolutions\CypherDSL\Clauses\SkipClause;
+use WikibaseSolutions\CypherDSL\Tests\Unit\TestHelper;
+use WikibaseSolutions\CypherDSL\Types\AnyType;
+use WikibaseSolutions\CypherDSL\Types\PropertyTypes\NumeralType;
+
+/**
+ * @covers \WikibaseSolutions\CypherDSL\Clauses\LimitClause
+ */
+class SkipClauseTest extends TestCase
+{
+    use TestHelper;
+
+    public function testEmptyClause(): void
+    {
+        $skip = new SkipClause();
+
+        $this->assertSame("", $skip->toQuery());
+        $this->assertNull($skip->getSkip());
+    }
+
+    public function testPattern(): void
+    {
+        $skip = new SkipClause();
+        $expression = $this->getQueryConvertableMock(NumeralType::class, "10");
+
+        $skip->setSkip($expression);
+
+        $this->assertSame("SKIP 10", $skip->toQuery());
+        $this->assertEquals($expression, $skip->getSkip());
+    }
+
+    /**
+     * @doesNotPerformAssertions
+     */
+    public function testAcceptsNumeralType(): void
+    {
+        $skip = new SkipClause();
+        $expression = $this->getQueryConvertableMock(NumeralType::class, "10");
+
+        $skip->setSkip($expression);
+
+        $skip->toQuery();
+    }
+
+    public function testDoesNotAcceptAnyType(): void
+    {
+        $skip = new SkipClause();
+        $expression = $this->getQueryConvertableMock(AnyType::class, "10");
+
+        $this->expectException(TypeError::class);
+
+        $skip->setSkip($expression);
+
+        $skip->toQuery();
+    }
+}