Flesh out HTTP/File unit tests

Author: jim-parry

system/HTTP/Files/UploadedFile.php

@@ -352,7 +352,7 @@ public function getExtension(): string
 
 	public function guessExtension(): ?string
 	{
-		return \Config\Mimes::guessExtensionFromType($this->getMimeType(), $this->getClientExtension());
+		return \Config\Mimes::guessExtensionFromType($this->getClientMimeType(), $this->getClientExtension());
 	}
 
 	//--------------------------------------------------------------------
@@ -366,7 +366,7 @@ public function guessExtension(): ?string
 	 */
 	public function getClientExtension(): string
 	{
-		return pathinfo($this->originalName, PATHINFO_EXTENSION);
+		return pathinfo($this->originalName, PATHINFO_EXTENSION) ?? '';
 	}
 
 	//--------------------------------------------------------------------

tests/system/HTTP/Files/FileCollectionTest.php

@@ -137,6 +137,38 @@ public function testAllReturnsValidMultipleFilesDifferentName()
 
 	//--------------------------------------------------------------------
 
+	public function testExtensionGuessing()
+	{
+		$_FILES = [
+			'userfile1' => [
+				'name'     => 'fileA.txt',
+				'type'     => 'text/plain',
+				'size'     => 124,
+				'tmp_name' => '/fileA.txt',
+				'error'    => 0,
+			],
+			'userfile2' => [
+				'name'     => 'fileB.txt',
+				'type'     => 'text/csv',
+				'size'     => 248,
+				'tmp_name' => '/fileB.txt',
+				'error'    => 0,
+			],
+		];
+
+		$collection = new FileCollection();
+
+		$file = $collection->getFile('userfile1');
+		$this->assertInstanceOf(UploadedFile::class, $file);
+		$this->assertEquals('txt', $file->getExtension());
+
+		$file = $collection->getFile('userfile2');
+		$this->assertInstanceOf(UploadedFile::class, $file);
+		$this->assertEquals('csv', $file->guessExtension());
+	}
+
+	//--------------------------------------------------------------------
+
 	/**
 	 * @group single
 	 */