[TASK] Add tests for DeclarationBlock constructor (#1350)

The class extends `RuleSet`, but the constructor behaviour needs to be tested
for each class.

Author: JakeQZ

tests/Unit/RuleSet/DeclarationBlockTest.php

@@ -53,6 +53,44 @@ public function implementsPositionable(): void
         self::assertInstanceOf(Positionable::class, $this->subject);
     }
 
+    /**
+     * @test
+     */
+    public function getLineNumberByDefaultReturnsNull(): void
+    {
+        $result = $this->subject->getLineNumber();
+
+        self::assertNull($result);
+    }
+
+    /**
+     * @return array<non-empty-string, array{0: int<1, max>|null}>
+     */
+    public function provideLineNumber(): array
+    {
+        return [
+            'null' => [null],
+            'line 1' => [1],
+            'line 42' => [42],
+        ];
+    }
+
+    /**
+     * @test
+     *
+     * @param int<1, max>|null $lineNumber
+     *
+     * @dataProvider provideLineNumber
+     */
+    public function getLineNumberReturnsLineNumberPassedToConstructor(?int $lineNumber): void
+    {
+        $subject = new DeclarationBlock($lineNumber);
+
+        $result = $subject->getLineNumber();
+
+        self::assertSame($lineNumber, $result);
+    }
+
     /**
      * @return array<non-empty-string, array{0: non-empty-string}>
      */