Support diffing against a non-existing composer.lock file

Author: wikando-ck

README.md

@@ -83,6 +83,7 @@ composer diff --help # Display detailed usage instructions
 ```shell script
 composer diff master # Compare current composer.lock with the one on master branch
 composer diff master:composer.lock develop:composer.lock -p # Compare master and develop branches, including platform dependencies
+composer diff /path/to/missing/composer.lock composer.lock # Compare a new lock file against a non-existing base lock file
 composer diff --no-dev # ignore dev dependencies
 composer diff -p # include platform dependencies
 composer diff -f json # Output as JSON instead of table

src/PackageDiff.php

@@ -213,6 +213,10 @@ private function getFileContents($path, $lockFile = true)
             return file_get_contents($localPath);
         }
 
+        if ($lockFile && false === strpos($originalPath, self::GIT_SEPARATOR) && $this->looksLikeComposerLockFile($localPath)) {
+            return '{}';
+        }
+
         if (false === strpos($originalPath, self::GIT_SEPARATOR)) {
             $path .= self::GIT_SEPARATOR.self::COMPOSER.($lockFile ? self::EXTENSION_LOCK : self::EXTENSION_JSON);
         }
@@ -226,6 +230,10 @@ private function getFileContents($path, $lockFile = true)
         $outputString = implode("\n", $output);
 
         if (0 !== $exit) {
+            if ($lockFile && $this->isMissingFileError($outputString)) {
+                return '{}';
+            }
+
             if ($lockFile) {
                 throw new \RuntimeException(sprintf('Could not open file %s or find it in git as %s: %s', $originalPath, $path, $outputString));
             }
@@ -237,6 +245,27 @@ private function getFileContents($path, $lockFile = true)
         return $outputString;
     }
 
+    /**
+     * @param string $path
+     *
+     * @return bool
+     */
+    private function looksLikeComposerLockFile($path)
+    {
+        return self::EXTENSION_LOCK === substr($path, -strlen(self::EXTENSION_LOCK));
+    }
+
+    /**
+     * @param string $gitOutput
+     *
+     * @return bool
+     */
+    private function isMissingFileError($gitOutput)
+    {
+        return false !== stripos($gitOutput, 'does not exist in') || false !== stripos($gitOutput, 'exists on disk, but not in');
+    }
+
+
     /**
      * @param string $path
      *

tests/PackageDiffTest.php

@@ -152,6 +152,43 @@ public function testLoadFromEmptyArray()
         $this->assertInstanceOf('Composer\Repository\ArrayRepository', $diff->loadPackagesFromArray(array(), true, true));
     }
 
+    public function testDiffAgainstMissingBaseLockFile()
+    {
+        $diff = new PackageDiff();
+
+        $prodOperations = $diff->getPackageDiff(
+            __DIR__.'/fixtures/missing/composer.lock',
+            __DIR__.'/fixtures/empty-target/composer.lock',
+            false,
+            false
+        );
+        $devOperations = $diff->getPackageDiff(
+            __DIR__.'/fixtures/missing/composer.lock',
+            __DIR__.'/fixtures/empty-target/composer.lock',
+            true,
+            false
+        );
+
+        $this->assertSame(array(
+            'install example/package 1.2.3',
+        ), array_map(array($this, 'entryToString'), $prodOperations->getArrayCopy()));
+        $this->assertSame(array(
+            'install example/dev-package 2.3.4',
+        ), array_map(array($this, 'entryToString'), $devOperations->getArrayCopy()));
+    }
+
+    public function testDiffAgainstMissingGitLockFilePath()
+    {
+        $diff = new PackageDiff();
+        $this->prepareGit();
+        $operations = $diff->getPackageDiff('HEAD:missing/composer.lock', '', false, false);
+
+        $this->assertNotEmpty($operations);
+        foreach ($operations as $entry) {
+            $this->assertInstanceOf('Composer\DependencyResolver\Operation\InstallOperation', $entry->getOperation());
+        }
+    }
+
     public function diffOperationsProvider()
     {
         return array(