Improve code coverage to satisfy Codecov

With the introduction of PHP8 compatibility, some `class_alias` code
has been introduced. We have not been able to make PHPUnit grok the
coverage of this code by other means.

Additionally, some annotations have been added to improve code coverage
metrics on code which actually has been covered but was not accounted.

codecov.yml

@@ -1,4 +1,5 @@
 # https://docs.codecov.io/docs/common-recipe-list
+# https://docs.codecov.io/docs/commit-status#patch-status
 
 coverage:
   status:

src/Crate/PDO/PDOImplementation.php

@@ -40,8 +40,10 @@
 
 use const PHP_VERSION_ID;
 
+// @codeCoverageIgnoreStart
 if (PHP_VERSION_ID >= 80000) {
     class_alias('\Crate\PDO\PDOImplementationPhp8', '\Crate\PDO\PDOImplementation');
 } else {
     class_alias('\Crate\PDO\PDOImplementationPhp7', '\Crate\PDO\PDOImplementation');
 }
+// @codeCoverageIgnoreEnd

src/Crate/PDO/PDOInterface.php

@@ -47,8 +47,10 @@
  *
  * @internal
  */
+// @codeCoverageIgnoreStart
 if (PHP_VERSION_ID >= 80000) {
     class_alias('\Crate\PDO\PDOInterfacePhp8', '\Crate\PDO\PDOInterface');
 } else {
     class_alias('\Crate\PDO\PDOInterfacePhp7', '\Crate\PDO\PDOInterface');
 }
+// @codeCoverageIgnoreEnd

test/CrateTest/PDO/PDOStatementTest.php

@@ -357,6 +357,7 @@ public function testRowCount()
 
     /**
      * @covers ::fetchColumn
+     * @covers \Crate\PDO\Exception\InvalidArgumentException
      */
     public function testFetchColumnWithInvalidColumnNumberType()
     {
@@ -565,6 +566,7 @@ public function testFetchAll($fetchStyle, array $expected)
     /**
      * @covers ::fetchAll
      * @covers ::doFetchAll
+     * @covers \Crate\PDO\Exception\InvalidArgumentException
      */
     public function testFetchAllWithFetchStyleFuncAndInvalidCallback()
     {
@@ -606,6 +608,7 @@ public function testFetchAllWithFetchStyleFunc()
     /**
      * @covers ::fetchAll
      * @covers ::doFetchAll
+     * @covers \Crate\PDO\Exception\InvalidArgumentException
      */
     public function testFetchAllWithFetchStyleColumnAndInvalidColumnIndexType()
     {
@@ -741,6 +744,7 @@ public function testGetColumnMeta()
     /**
      * @covers ::setFetchMode
      * @covers ::doSetFetchMode
+     * @covers \Crate\PDO\Exception\InvalidArgumentException
      */
     public function testSetFetchModeWithColumnAndMissingColNo()
     {
@@ -755,6 +759,7 @@ public function testSetFetchModeWithColumnAndMissingColNo()
     /**
      * @covers ::setFetchMode
      * @covers ::doSetFetchMode
+     * @covers \Crate\PDO\Exception\InvalidArgumentException
      */
     public function testSetFetchModeWithColumnAndInvalidColNo()
     {
@@ -830,6 +835,8 @@ public function testSetFetchModeWithInvalidFetchStyle()
     /**
      * @covers ::setFetchMode
      * @covers ::doSetFetchMode
+     * @covers \Crate\PDO\Exception\InvalidArgumentException
+     *
      * @dataProvider fetchModeStyleProvider
      *
      * @param int $fetchStyle

test/CrateTest/PDO/PDOTest.php

@@ -315,6 +315,7 @@ public function testLastInsertIdThrowsUnsupportedException()
      * Not all things have been implemented yet.
      *
      * @requires PHP >= 8
+     * @covers ::query
      *
      * @dataProvider fetchModeStyleProvider
      * @param $fetchMode