Increased test coverage

src/Clause/Condition.php

@@ -27,7 +27,7 @@
 use SQLBuilder\Operator\Operator;
 use SQLBuilder\Stringable_;
 
-class Condition implements Stringable_
+class Condition extends Expression implements Stringable_
 {
   protected ?Stringable_ $parent;
   protected array $expressions;
@@ -215,7 +215,7 @@ protected function buildExpressions(): string
       }
 
       if ($expression instanceof Expression) {
-        $str .= $expression->__toString();
+        $str .= $expression;
       } elseif (is_string($expression)) {
         $str .= $expression;
       } else {

src/Clause/OrderBy.php

@@ -46,10 +46,6 @@ public function __construct($expression, $sorting = self::ASC, Stringable_ $pare
 
   public function __toString(): string
   {
-    if (empty($this->expressionList)) {
-      return '';
-    }
-
     $str = '';
     foreach ($this->expressionList as $orderBy) {
       $str .= ', ' . Helper::quoteColumn($orderBy[0]);

src/Expression/Expression.php

@@ -8,8 +8,4 @@
 
 abstract class Expression implements Stringable_
 {
-  public function __toString(): string
-  {
-    return '';
-  }
 }

src/Operator/Operator.php

@@ -8,8 +8,4 @@
 
 abstract class Operator implements Stringable_
 {
-  public function __toString(): string
-  {
-    return '';
-  }
 }

tests/Clause/OrderByTest.php

@@ -18,7 +18,7 @@ public function testToString()
 
     $orderBy = new OrderBy([
       'col_name' => OrderBy::DESC,
-      'col_name_1' => OrderBy::ASC,
+      'col_name_1',
     ]);
 
     $this->assertEquals(

tests/SqlBuilderTest.php

@@ -91,7 +91,6 @@ public function testDelete(): void
       ->from('table_name')
       ->where()
       ->equal('col1', 2)
-      ->and()
       ->equal('col2', 23)
       ->limit(3);