SqlPreprocessor: a multi-insert row with a missing or unexpected column warns

Columns are taken from the first row, so a later row that misses one used to
be silently filled with NULL (with an "Undefined array key" warning), and a
column the first row does not have was dropped without a trace. Both now warn.

Author: dg

src/Database/SqlPreprocessor.php

@@ -260,10 +260,19 @@ private function formatMultiInsert(array $groups): string
 
 		$cols = array_keys(iterator_to_array($groups[0]));
 		$vals = [];
-		foreach ($groups as $group) {
+		foreach ($groups as $i => $group) {
+			$group = is_array($group) ? $group : iterator_to_array($group);
 			$rowVals = [];
 			foreach ($cols as $k) {
-				$rowVals[] = $this->formatValue($group[$k]);
+				if (!array_key_exists($k, $group)) { // the column would be silently filled with NULL
+					trigger_error("Missing value for column '$k' in multi-insert row #$i.", E_USER_WARNING);
+				}
+
+				$rowVals[] = $this->formatValue($group[$k] ?? null);
+			}
+
+			if ($extra = array_diff_key($group, array_flip($cols))) { // the column is taken from the first row only
+				trigger_error("Unexpected column '" . array_key_first($extra) . "' in multi-insert row #$i.", E_USER_WARNING);
 			}
 
 			$vals[] = implode(', ', $rowVals);

tests/Database/SqlPreprocessor.phpt

@@ -528,6 +528,37 @@ test('Detects incorrect multi-insert usage', function () use ($preprocessor) {
 });
 
 
+test('multi-insert row with a missing or unexpected column warns', function () use ($preprocessor) {
+	Assert::error(
+		fn() => $preprocessor->process(['INSERT INTO author', [
+			['name' => 'Catelyn Stark', 'born' => null],
+			['name' => 'Sansa Stark'], // the column would be silently filled with NULL
+		]]),
+		E_USER_WARNING,
+		"Missing value for column 'born' in multi-insert row #1.",
+	);
+
+	Assert::error(
+		fn() => $preprocessor->process(['INSERT INTO author', [
+			['name' => 'Catelyn Stark'],
+			['name' => 'Sansa Stark', 'born' => null], // the column would be silently dropped
+		]]),
+		E_USER_WARNING,
+		"Unexpected column 'born' in multi-insert row #1.",
+	);
+
+	[$sql, $params] = $preprocessor->process(['INSERT INTO author', [
+		['name' => 'Catelyn Stark', 'born' => null],
+		['born' => null, 'name' => 'Sansa Stark'], // different key order is fine
+	]]);
+	Assert::same(reformat([
+		'sqlite' => 'INSERT INTO author ([name], [born]) SELECT ?, NULL UNION ALL SELECT ?, NULL',
+		'INSERT INTO author ([name], [born]) VALUES (?, NULL), (?, NULL)',
+	]), $sql);
+	Assert::same(['Catelyn Stark', 'Sansa Stark'], $params);
+});
+
+
 test('multi-row INSERT query', function () use ($preprocessor) {
 	[$sql, $params] = $preprocessor->process(['INSERT INTO author', [
 		['name' => 'Catelyn Stark', 'born' => new DateTime('2011-11-11')],