Allow downgrades for our brave developers, that switch between branches

lib/private/updater.php

@@ -256,7 +256,7 @@ class Updater extends BasicEmitter {
 	 */
 	public function isUpgradePossible($oldVersion, $newVersion, $allowedPreviousVersion) {
 		return (version_compare($allowedPreviousVersion, $oldVersion, '<=')
-			&& version_compare($oldVersion, $newVersion, '<='));
+			&& (version_compare($oldVersion, $newVersion, '<=') || $this->config->getSystemValue('debug', false)));
 	}
 
 	/**

lib/private/util.php

@@ -1483,6 +1483,7 @@ class OC_Util {
 	 *
 	 * @param \OCP\IConfig $config
 	 * @return bool whether the core or any app needs an upgrade
+	 * @throws \OC\HintException When the upgrade from the given version is not allowed
 	 */
 	public static function needUpgrade(\OCP\IConfig $config) {
 		if ($config->getSystemValue('installed', false)) {
@@ -1491,6 +1492,19 @@ class OC_Util {
 			$versionDiff = version_compare($currentVersion, $installedVersion);
 			if ($versionDiff > 0) {
 				return true;
+			} else if ($config->getSystemValue('debug', false) && $versionDiff < 0) {
+				// downgrade with debug
+				$installedMajor = explode('.', $installedVersion);
+				$installedMajor = $installedMajor[0] . '.' . $installedMajor[1];
+				$currentMajor = explode('.', $currentVersion);
+				$currentMajor = $currentMajor[0] . '.' . $currentMajor[1];
+				if ($installedMajor === $currentMajor) {
+					// Same major, allow downgrade for developers
+					return true;
+				} else {
+					// downgrade attempt, throw exception
+					throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');
+				}
 			} else if ($versionDiff < 0) {
 				// downgrade attempt, throw exception
 				throw new \OC\HintException('Downgrading is not supported and is likely to cause unpredictable issues (from ' . $installedVersion . ' to ' . $currentVersion . ')');

tests/lib/updater.php

@@ -27,7 +27,7 @@ use OCP\ILogger;
 use OC\IntegrityCheck\Checker;
 
 class UpdaterTest extends \Test\TestCase {
-	/** @var IConfig */
+	/** @var IConfig|\PHPUnit_Framework_MockObject_MockObject */
 	private $config;
 	/** @var HTTPHelper */
 	private $httpHelper;
@@ -136,9 +136,33 @@ class UpdaterTest extends \Test\TestCase {
 			['9.0.0.0', '8.0.0.0', '7.0', false],
 			['9.1.0.0', '8.0.0.0', '7.0', false],
 			['8.2.0.0', '8.1.0.0', '8.0', false],
+
+			// With debug enabled
+			['8.0.0.0', '8.2.0.0', '8.1', false, true],
+			['8.1.0.0', '8.2.0.0', '8.1', true, true],
+			['8.2.0.1', '8.2.0.1', '8.1', true, true],
+			['8.3.0.0', '8.2.0.0', '8.1', true, true],
 		];
 	}
 
+	/**
+	 * @dataProvider versionCompatibilityTestData
+	 *
+	 * @param string $oldVersion
+	 * @param string $newVersion
+	 * @param string $allowedVersion
+	 * @param bool $result
+	 * @param bool $debug
+	 */
+	public function testIsUpgradePossible($oldVersion, $newVersion, $allowedVersion, $result, $debug = false) {
+		$this->config->expects($this->any())
+			->method('getSystemValue')
+			->with('debug', false)
+			->willReturn($debug);
+
+		$this->assertSame($result, $this->updater->isUpgradePossible($oldVersion, $newVersion, $allowedVersion));
+	}
+
 	public function testSetSimulateStepEnabled() {
 		$this->updater->setSimulateStepEnabled(true);
 		$this->assertSame(true, $this->invokePrivate($this->updater, 'simulateStepEnabled'));
@@ -160,18 +184,6 @@ class UpdaterTest extends \Test\TestCase {
 		$this->assertSame(false, $this->invokePrivate($this->updater, 'skip3rdPartyAppsDisable'));
 	}
 
-	/**
-	 * @dataProvider versionCompatibilityTestData
-	 *
-	 * @param string $oldVersion
-	 * @param string $newVersion
-	 * @param string $allowedVersion
-	 * @param bool $result
-	 */
-	public function testIsUpgradePossible($oldVersion, $newVersion, $allowedVersion, $result) {
-		$this->assertSame($result, $this->updater->isUpgradePossible($oldVersion, $newVersion, $allowedVersion));
-	}
-
 	public function testCheckInCache() {
 		$expectedResult = [
 			'version' => '8.0.4.2',