Reuse normal installer logic for locked installs

src/Composer/Command/InstallCommand.php

@@ -16,6 +16,7 @@ use Composer\DependencyResolver;
 use Composer\DependencyResolver\Pool;
 use Composer\DependencyResolver\Request;
 use Composer\DependencyResolver\Operation;
+use Composer\Package\LinkConstraint\VersionConstraint;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 
@@ -47,20 +48,6 @@ EOT
     {
         $composer = $this->getComposer();
 
-        if ($composer->getLocker()->isLocked()) {
-            $output->writeln('<info>Found lockfile. Reading</info>');
-
-            $installationManager = $composer->getInstallationManager();
-            foreach ($composer->getLocker()->getLockedPackages() as $package) {
-                if (!$installationManager->isPackageInstalled($package)) {
-                    $operation = new Operation\InstallOperation($package, 'lock resolving');
-                    $installationManager->execute($operation);
-                }
-            }
-
-            return 0;
-        }
-
         // creating repository pool
         $pool = new Pool;
         $pool->addRepository($composer->getRepositoryManager()->getLocalRepository());
@@ -70,8 +57,17 @@ EOT
 
         // creating requirements request
         $request = new Request($pool);
-        foreach ($composer->getPackage()->getRequires() as $link) {
-            $request->install($link->getTarget(), $link->getConstraint());
+        if ($composer->getLocker()->isLocked()) {
+            $output->writeln('> Found lockfile. Reading.');
+
+            foreach ($composer->getLocker()->getLockedPackages() as $package) {
+                $constraint = new VersionConstraint('=', $package->getVersion());
+                $request->install($package->getName(), $constraint);
+            }
+        } else {
+            foreach ($composer->getPackage()->getRequires() as $link) {
+                $request->install($link->getTarget(), $link->getConstraint());
+            }
         }
 
         // prepare solver
@@ -85,8 +81,10 @@ EOT
             $installationManager->execute($operation);
         }
 
-        $composer->getLocker()->lockPackages($localRepo->getPackages());
-        $output->writeln('> Locked');
+        if (!$composer->getLocker()->isLocked()) {
+            $composer->getLocker()->lockPackages($localRepo->getPackages());
+            $output->writeln('> Locked');
+        }
 
         $localRepo->write();
         $output->writeln('> Done');