fix(dav): Update 403 error message

* The user should get a more friendly warning when their desktop client version is not supported anymore by the server.
  See #nextcloud/desktop/issues/6273
* Update BlockLegacyClientPluginTest to reflect the new 403 error message.

Signed-off-by: Camila Ayres <hello@camilasan.com>

apps/dav/lib/Connector/Sabre/BlockLegacyClientPlugin.php

@@ -51,7 +51,8 @@ public function beforeHandler(RequestInterface $request) {
 		preg_match(IRequest::USER_AGENT_CLIENT_DESKTOP, $userAgent, $versionMatches);
 		if (isset($versionMatches[1]) &&
 			version_compare($versionMatches[1], $minimumSupportedDesktopVersion) === -1) {
-			throw new \Sabre\DAV\Exception\Forbidden('Unsupported client version.');
+			$customClientDesktopLink = $this->config->getSystemValue('customclient_desktop', 'https://nextcloud.com/install/#install-clients');
+			throw new \Sabre\DAV\Exception\Forbidden('This version of the client is unsupported. Upgrade to <a href="'.$customClientDesktopLink.'">version '.$minimumSupportedDesktopVersion.' or later</a>.');
 		}
 	}
 }

apps/dav/tests/unit/Connector/Sabre/BlockLegacyClientPluginTest.php

@@ -45,7 +45,20 @@ public function oldDesktopClientProvider(): array {
 	 */
 	public function testBeforeHandlerException(string $userAgent): void {
 		$this->expectException(\Sabre\DAV\Exception\Forbidden::class);
-		$this->expectExceptionMessage('Unsupported client version.');
+
+		$this->config
+			->expects($this->once())
+			->method('getSystemValue')
+			->with('customclient_desktop', 'https://nextcloud.com/install/#install-clients')
+			->willReturn('https://nextcloud.com/install/#install-clients');
+
+		$this->config
+			->expects($this->once())
+			->method('getSystemValue')
+			->with('minimum.supported.desktop.version', '2.3.0')
+			->willReturn('1.7.0');
+
+		$this->expectExceptionMessage('This version of the client is unsupported. Upgrade to <a href="https://nextcloud.com/install/#install-clients">version 1.7.0 or later</a>.');
 
 		/** @var RequestInterface|MockObject $request */
 		$request = $this->createMock('\Sabre\HTTP\RequestInterface');
@@ -55,11 +68,6 @@ public function testBeforeHandlerException(string $userAgent): void {
 			->with('User-Agent')
 			->willReturn($userAgent);
 
-		$this->config
-			->expects($this->once())
-			->method('getSystemValue')
-			->with('minimum.supported.desktop.version', '2.3.0')
-			->willReturn('1.7.0');
 
 		$this->blockLegacyClientVersionPlugin->beforeHandler($request);
 	}