[gnome-builder] npm: ensure we have a package.json to work with

[Christian Hergert <chergert src gnome org>]

commit cb6de2d5931beff2eacf4e6c6afd349bdf005adc
Author: Christian Hergert <chergert redhat com>
Date:   Fri Apr 19 11:24:01 2019 -0700

    npm: ensure we have a package.json to work with
    
    If the user opened the directory as the project, project_file might not
    be a package.json, but instead the directory.
    
    This adds a helper to ensure that 'package.json' is used when resolving
    what directory is needed in those cases.
    
    Fixes #888

 src/plugins/npm/npm_plugin.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/src/plugins/npm/npm_plugin.py b/src/plugins/npm/npm_plugin.py
index 9f82875f9..f920d7ca0 100644
--- a/src/plugins/npm/npm_plugin.py
+++ b/src/plugins/npm/npm_plugin.py
@@ -53,6 +53,11 @@ class NPMBuildSystem(Ide.Object, Ide.BuildSystem):
     def do_get_priority(self):
         return 100
 
+    def get_package_json(self):
+        if self.props.project_file.get_basename() != 'package.json':
+            return self.props.project_file.get_child('package.json')
+        else:
+            return self.props.project_file
 
 class NPMPipelineAddin(Ide.Object, Ide.PipelineAddin):
     """
@@ -68,7 +73,7 @@ class NPMPipelineAddin(Ide.Object, Ide.PipelineAddin):
         if type(build_system) != NPMBuildSystem:
             return
 
-        package_json = build_system.props.project_file
+        package_json = build_system.get_package_json()
         config = pipeline.get_config()
         builddir = pipeline.get_builddir()
         runtime = config.get_runtime()
@@ -193,7 +198,7 @@ class NPMBuildTargetProvider(Ide.Object, Ide.BuildTargetProvider):
                                          code=Gio.IOErrorEnum.NOT_SUPPORTED))
             return
 
-        project_file = build_system.project_file
+        project_file = build_system.get_package_json()
         project_file.load_contents_async(cancellable, self._on_package_json_loaded, task)
 
     def do_get_targets_finish(self, result):