Add the ability to disable snapshots creation

Author: mathieutu

src/MatchesSnapshots.php

@@ -152,6 +152,18 @@ protected function shouldUpdateSnapshots(): bool
         return in_array('--update-snapshots', $_SERVER['argv'], true);
     }
 
+    /*
+     * Determines whether or not the snapshot should be created instead of
+     * matched.
+     *
+     * Override this method it you want to use a different flag or mechanism
+     * than `-d --no-create-snapshots`.
+     */
+    protected function shouldCreateSnapshots(): bool
+    {
+        return !in_array('--no-create-snapshots', $_SERVER['argv'], true);
+    }
+
     protected function doSnapshotAssertion($actual, Driver $driver)
     {
         $this->snapshotIncrementor++;
@@ -163,6 +175,8 @@ protected function doSnapshotAssertion($actual, Driver $driver)
         );
 
         if (! $snapshot->exists()) {
+            $this->assertSnapshotShouldBeCreated($snapshot->filename());
+
             $this->createSnapshotAndMarkTestIncomplete($snapshot, $actual);
         }
 
@@ -231,6 +245,8 @@ protected function doFileSnapshotAssertion(string $filePath): void
         }
 
         if (! $fileSystem->has($snapshotId)) {
+            $this->assertSnapshotShouldBeCreated($failedSnapshotId);
+
             $fileSystem->copy($filePath, $snapshotId);
 
             $this->registerSnapshotChange("File snapshot created for {$snapshotId}");
@@ -288,4 +304,17 @@ protected function registerSnapshotChange(string $message): void
     {
         $this->snapshotChanges[] = $message;
     }
+
+    protected function assertSnapshotShouldBeCreated(string $snapshotFileName): void
+    {
+        if ($this->shouldCreateSnapshots()) {
+            return;
+        }
+
+        $this->fail(
+            "Snapshot \"$snapshotFileName\" does not exist.\n".
+            'You can automatically create it by removing '.
+            '`-d --no-create-snapshots` of PHPUnit\'s CLI arguments.'
+        );
+    }
 }

tests/Integration/MatchesSnapshotTest.php

@@ -2,6 +2,7 @@
 
 namespace Spatie\Snapshots\Test\Integration;
 
+use PHPUnit\Framework\AssertionFailedError;
 use PHPUnit\Framework\ExpectationFailedException;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
@@ -18,10 +19,15 @@ public function setUp(): void
         $this->setUpComparesSnapshotFiles();
 
         $updateArgument = array_search('--update-snapshots', $_SERVER['argv']);
+        $noCreateArgument = array_search('--no-create-snapshots', $_SERVER['argv']);
 
         if ($updateArgument) {
             unset($_SERVER['argv'][$updateArgument]);
         }
+
+        if ($noCreateArgument) {
+            unset($_SERVER['argv'][$noCreateArgument]);
+        }
     }
 
     /** @test */
@@ -459,4 +465,37 @@ private function getMatchesSnapshotMock(): MockObject
 
         return $matchesSnapshotMock;
     }
+
+
+    /** @test */
+    public function it_doesnt_create_a_regular_snapshot_and_mismatches_if_asked()
+    {
+        $_SERVER['argv'][] = '--no-create-snapshots';
+
+        $mockTrait = $this->getMatchesSnapshotMock();
+
+        $this->expectFail(
+            $mockTrait,
+            "Snapshot \"MatchesSnapshotTest__it_doesnt_create_a_regular_snapshot_and_mismatches_if_asked__1.txt\" does not exist.\n" .
+            'You can automatically create it by removing `-d --no-create-snapshots` of PHPUnit\'s CLI arguments.'
+        );
+
+        $mockTrait->assertMatchesSnapshot('Bar');
+    }
+
+    /** @test */
+    public function it_doesnt_create_a_file_snapshot_and_mismatches_if_asked()
+    {
+        $_SERVER['argv'][] = '--no-create-snapshots';
+
+        $mockTrait = $this->getMatchesSnapshotMock();
+
+        $this->expectFail(
+            $mockTrait,
+            "Snapshot \"MatchesSnapshotTest__it_doesnt_create_a_file_snapshot_and_mismatches_if_asked__1.jpg_failed.jpg\" does not exist.\n" .
+            'You can automatically create it by removing `-d --no-create-snapshots` of PHPUnit\'s CLI arguments.'
+        );
+
+        $mockTrait->assertMatchesFileSnapshot(__DIR__.'/stubs/test_files/friendly_man.jpg');
+    }
 }