Deduplicate patch collection as patches are added

docs/usage/defining-patches.md

@@ -120,6 +120,13 @@ If you're defining patches in `patches.json` (or some other separate patches fil
 }
 ```
 
+## Duplicate patches
+
+If the same patch is defined in multiple places, the first one added to the patch collection "wins". Subsequent definitions of the same patch will be ignored without emitting an error. The criteria used for determining whether two patches are the same are:
+
+* They have the same URL
+* They have the same sha256 hash
+
 ## `patches.lock.json`
 
 If `patches.lock.json` does not exist the first time you run `composer install` with this plugin enabled, one will be created for you. Generally, you shouldn't need to do anything with this file: commit it to your project repository alongside your `composer.json` and `composer.lock`, and commit any changes when you change your patch definitions.

src/PatchCollection.php

@@ -23,6 +23,22 @@ class PatchCollection implements JsonSerializable
      */
     public function addPatch(Patch $patch)
     {
+        if (array_key_exists($patch->package, $this->patches)) {
+            foreach ($this->patches[$patch->package] as $existing_patch) {
+                $has_same_url = ($patch->url === $existing_patch->url);
+                $has_same_sha = (
+                    isset($patch->sha256) &&
+                    isset($existing_patch->sha256) &&
+                    ($patch->sha256 === $existing_patch->sha256)
+                );
+
+                if ($has_same_url || $has_same_sha) {
+                    // If we already have the patch, don't try to add it again.
+                    return;
+                }
+            }
+        }
+
         $this->patches[$patch->package][] = $patch;
     }
 

tests/_data/dummyPatches.json

@@ -6,17 +6,17 @@
                 "description": "Test patch"
             },
             {
-                "url": "https://drupal.org",
+                "url": "https://drupal.org/foo",
                 "description": "Test patch"
             }
         ],
         "test/package2": [
             {
-                "url": "https://drupal.org",
+                "url": "https://drupal.org/bar",
                 "description": "Test patch"
             },
             {
-                "url": "https://drupal.org",
+                "url": "https://drupal.org/baz",
                 "description": "Test patch"
             }
         ]

tests/unit/PatchCollectionTest.php

@@ -22,21 +22,25 @@ public function testPatchCollectionAddRetrieve()
         $patch1 = new Patch();
         $patch1->package = 'some/package';
         $patch1->description = 'patch1';
+        $patch1->url = '1';
         $collection->addPatch($patch1);
 
         $patch2 = new Patch();
         $patch2->package = 'some/package';
         $patch2->description = 'patch2';
+        $patch2->url = '2';
         $collection->addPatch($patch2);
 
         $patch3 = new Patch();
         $patch3->package = 'other/package';
         $patch3->description = 'patch3';
+        $patch3->url = '3';
         $collection->addPatch($patch3);
 
         $patch4 = new Patch();
         $patch4->package = 'other/package';
         $patch4->description = 'patch4';
+        $patch4->url = '4';
         $collection->addPatch($patch4);
 
         foreach (['some/package', 'other/package'] as $package_name) {
@@ -64,6 +68,45 @@ public function testPatchCollectionAddRetrieve()
         $this->assertContains('some/package', $packages);
     }
 
+    public function testPatchDeduplication()
+    {
+        $collection = new PatchCollection();
+
+        // First, make sure that we don't get anything out of an empty collection.
+        $this->assertEmpty($collection->getPatchesForPackage('some/package'));
+
+        // Add two patches with the same URL.
+        $patch1 = new Patch();
+        $patch1->package = 'some/package';
+        $patch1->description = 'patch1';
+        $patch1->url = 'https://example.com';
+        $collection->addPatch($patch1);
+
+        $patch2 = new Patch();
+        $patch2->package = 'some/package';
+        $patch2->description = 'patch2';
+        $patch2->url = 'https://example.com';
+        $collection->addPatch($patch2);
+
+        // We should only have one patch now.
+        $this->assertCount(1, $collection->getPatchedPackages('some/package'));
+        $this->assertEquals('patch1', $collection->getPatchesForPackage('some/package')[0]->description);
+
+        // Start over to test deduplication with sha256.
+        $collection = new PatchCollection();
+        $this->assertEmpty($collection->getPatchesForPackage('some/package'));
+
+        $patch1->sha256 = 'asdf';
+        $patch2->sha256 = 'asdf';
+        $patch2->url = 'https://example.com#something-different';
+
+        $collection->addPatch($patch1);
+        $collection->addPatch($patch2);
+
+        $this->assertCount(1, $collection->getPatchedPackages('some/package'));
+        $this->assertEquals('patch1', $collection->getPatchesForPackage('some/package')[0]->description);
+    }
+
     public function testSerializeDeserialize()
     {
         $collection = new PatchCollection();
@@ -77,7 +120,7 @@ public function testSerializeDeserialize()
         $patch2 = new Patch();
         $patch2->package = 'another/package';
         $patch2->description = 'patch2';
-        $patch2->url = 'https://example.com/test.patch';
+        $patch2->url = 'https://example.com/test2.patch';
         $patch2->extra = [];
 
         $collection->addPatch($patch1);