From 5d4ea6edc0c6ec60063347772bf01b7461e44cf6 Mon Sep 17 00:00:00 2001
From: "J. King" <jking@jkingweb.ca>
Date: Sun, 19 Nov 2017 15:49:41 -0500
Subject: [PATCH] Add ResultEmpty class

This allows for the creation of synthetic empty result sets
---
 lib/Db/AbstractResult.php    | 14 +++++++++-----
 lib/Db/ResultEmpty.php       | 25 ++++++++++++++++++++++++
 tests/Db/TestResultEmpty.php | 37 ++++++++++++++++++++++++++++++++++++
 tests/phpunit.xml            |  1 +
 4 files changed, 72 insertions(+), 5 deletions(-)
 create mode 100644 lib/Db/ResultEmpty.php
 create mode 100644 tests/Db/TestResultEmpty.php

diff --git a/lib/Db/AbstractResult.php b/lib/Db/AbstractResult.php
index c1a60c65..fe4df26d 100644
--- a/lib/Db/AbstractResult.php
+++ b/lib/Db/AbstractResult.php
@@ -17,15 +17,19 @@ abstract class AbstractResult implements Result {
             $out = array_shift($this->cur);
             $this->next();
             return $out;
+        } else {
+            return null;
         }
-        $this->next();
-        return null;
     }
 
     public function getRow() {
-        $out = ($this->valid() ? $this->cur : null);
-        $this->next();
-        return $out;
+        if ($this->valid()) {
+            $out = $this->cur;
+            $this->next();
+            return $out;
+        } else {
+            return null;
+        }
     }
 
     public function getAll(): array {
diff --git a/lib/Db/ResultEmpty.php b/lib/Db/ResultEmpty.php
new file mode 100644
index 00000000..f11d75ea
--- /dev/null
+++ b/lib/Db/ResultEmpty.php
@@ -0,0 +1,25 @@
+<?php
+/** @license MIT
+ * Copyright 2017 J. King, Dustin Wilson et al.
+ * See LICENSE and AUTHORS files for details */
+
+declare(strict_types=1);
+namespace JKingWeb\Arsse\Db;
+
+use JKingWeb\Arsse\Db\Exception;
+
+class ResultEmpty extends AbstractResult {
+    public function changes() {
+        return 0;
+    }
+
+    public function lastId() {
+        return 0;
+    }
+
+    // PHP iterator methods
+
+    public function valid() {
+        return false;
+    }
+}
diff --git a/tests/Db/TestResultEmpty.php b/tests/Db/TestResultEmpty.php
new file mode 100644
index 00000000..0a6cbe9f
--- /dev/null
+++ b/tests/Db/TestResultEmpty.php
@@ -0,0 +1,37 @@
+<?php
+declare(strict_types=1);
+namespace JKingWeb\Arsse;
+
+/** @covers \JKingWeb\Arsse\Db\ResultEmpty<extended> */
+class TestResultEmpty extends Test\AbstractTest {
+
+    public function testGetChangeCountAndLastInsertId() {
+        $r = new Db\ResultEmpty;
+        $this->assertEquals(0, $r->changes());
+        $this->assertEquals(0, $r->lastId());
+    }
+
+    public function testIterateOverResults() {
+        $rows = [];
+        foreach (new Db\ResultEmpty as $index => $row) {
+            $rows[$index] = $row['col'];
+        }
+        $this->assertEquals([], $rows);
+    }
+
+    public function testGetSingleValues() {
+        $test = new Db\ResultEmpty;
+        $this->assertSame(null, $test->getValue());
+    }
+
+    public function testGetRows() {
+        $test = new Db\ResultEmpty;
+        $this->assertSame(null, $test->getRow());
+    }
+
+    public function testGetAllRows() {
+        $test = new Db\ResultEmpty;
+        $rows = [];
+        $this->assertEquals($rows, $test->getAll());
+    }
+}
\ No newline at end of file
diff --git a/tests/phpunit.xml b/tests/phpunit.xml
index 9d65e7b2..3feab1bc 100644
--- a/tests/phpunit.xml
+++ b/tests/phpunit.xml
@@ -56,6 +56,7 @@
     <testsuite name="Database drivers">
         <file>Db/TestTransaction.php</file>
         <file>Db/TestResultAggregate.php</file>
+        <file>Db/TestResultEmpty.php</file>
         <file>Db/SQLite3/TestDbResultSQLite3.php</file>
         <file>Db/SQLite3/TestDbStatementSQLite3.php</file>
         <file>Db/SQLite3/TestDbDriverCreationSQLite3.php</file>