1 files changed, 70 insertions, 0 deletions
diff --git a/tests/StructureTest.php b/tests/StructureTest.php
new file mode 100644
index 0000000..80d94fe
--- /dev/null
+++ b/tests/StructureTest.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Zhineng\Snowflake\Tests;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use Zhineng\Snowflake\Constant;
+use Zhineng\Snowflake\Sequence;
+use Zhineng\Snowflake\Structure;
+
+#[CoversClass(Structure::class)]
+final class StructureTest extends TestCase
+{
+    public function testAddFieldAndRetrieveComponents(): void
+    {
+        $struct = new Structure;
+        $struct->add(Constant::make('machine_id', 10));
+        $this->assertCount(1, $struct->components());
+    }
+
+    public function testAddMultipleFields(): void
+    {
+        $struct = new Structure;
+        $struct->add(Constant::make('machine_id', 5));
+        $struct->add(Constant::make('datacenter_id', 5));
+        $this->assertCount(2, $struct->components());
+    }
+
+    public function testOffsetsAreCalculatedCorrectly(): void
+    {
+        $struct = new Structure;
+        $struct->add($machineId = Constant::make('machine_id', 5));
+        $struct->add($dataCenterId = Constant::make('datacenter_id', 5));
+        $this->assertSame(0, $machineId->offset());
+        $this->assertSame(5, $dataCenterId->offset());
+    }
+
+    public function testSizeResolution(): void
+    {
+        $struct = new Structure;
+        $struct->add(Constant::make('machine_id', 5));
+        $struct->add(Constant::make('datacenter_id', 5));
+        $this->assertSame(10, $struct->size());
+    }
+
+    public function testAtMostOneSequenceIsAllowed(): void
+    {
+        $struct = new Structure;
+        $struct->add(Sequence::make('seq1', 12));
+
+        $this->expectException(\LogicException::class);
+        $this->expectExceptionMessage('Only one sequence field is allowed in a structure.');
+
+        $struct->add(Sequence::make('seq2', 12));
+    }
+
+    public function testTotalSizeCannotExceed63Bits(): void
+    {
+        $struct = new Structure;
+        $struct->add(Constant::make('field1', 32));
+        $struct->add(Constant::make('field2', 31));
+
+        $this->expectException(\OverflowException::class);
+        $this->expectExceptionMessage('Total structure size cannot exceed 63 bits.');
+
+        $struct->add(Constant::make('field3', 1));
+    }
+}