Properly look up entry in manifest when name is given with extension (#2919)

Author: leonid-shevtsov

lib/webpacker/manifest.rb

@@ -92,7 +92,7 @@ def load
     # When the user provides a name with a file extension, we want to try to strip it off.
     def manifest_name(name, pack_type)
       return name if File.extname(name.to_s).empty?
-      File.basename(name, pack_type)
+      File.basename(name, ".#{pack_type}")
     end
 
     def manifest_type(pack_type)

test/manifest_test.rb

@@ -25,6 +25,14 @@ def test_lookup_success!
     assert_equal Webpacker.manifest.lookup!("bootstrap.js"), "/packs/bootstrap-300631c4f0e0f9c865bc.js"
   end
 
+  def test_lookup_with_chunks_without_extension_success!
+    assert_equal Webpacker.manifest.lookup_pack_with_chunks!("bootstrap", type: :javascript), ["/packs/bootstrap-300631c4f0e0f9c865bc.js"]
+  end
+
+  def test_lookup_with_chunks_with_extension_success!
+    assert_equal Webpacker.manifest.lookup_pack_with_chunks!("bootstrap.js", type: :javascript), ["/packs/bootstrap-300631c4f0e0f9c865bc.js"]
+  end
+
   def test_lookup_nil
     assert_nil Webpacker.manifest.lookup("foo.js")
   end