[gjs] function: Print class name in error message

[Philip Chimento <pchimento src gnome org>]

commit 421eed2f0885a16f790174b4e7eb4eac3fe14c6d
Author: Philip Chimento <philip chimento gmail com>
Date:   Thu Jan 12 22:31:37 2017 -0800

    function: Print class name in error message
    
    If throwing an exception about too few arguments passed to a GI function,
    and if the function is a message, then we should print the name of the
    "container info" as well. That is, "Gio.File.read" rather than
    "Gio.read".
    
    https://bugzilla.gnome.org/show_bug.cgi?id=642506

 gi/function.cpp                      |   24 +++++++++++++++++-------
 installed-tests/js/testExceptions.js |   12 ++++++++++++
 2 files changed, 29 insertions(+), 7 deletions(-)
---
diff --git a/gi/function.cpp b/gi/function.cpp
index c38bbca..d061d74 100644
--- a/gi/function.cpp
+++ b/gi/function.cpp
@@ -745,13 +745,23 @@ gjs_invoke_c_function(JSContext                              *context,
      */
 
     if (args.length() < function->expected_js_argc) {
-        gjs_throw(context,
-                  "Too few arguments to %s %s.%s expected %d got %" G_GSIZE_FORMAT,
-                  is_method ? "method" : "function",
-                  g_base_info_get_namespace( (GIBaseInfo*) function->info),
-                  g_base_info_get_name( (GIBaseInfo*) function->info),
-                  function->expected_js_argc,
-                  args.length());
+        auto baseinfo = static_cast<GIBaseInfo *>(function->info);
+        if (is_method) {
+            gjs_throw(context, "Too few arguments to method %s.%s.%s: "
+                      "expected %d, got %" G_GSIZE_FORMAT,
+                      g_base_info_get_namespace(baseinfo),
+                      g_base_info_get_name(g_base_info_get_container(baseinfo)),
+                      g_base_info_get_name(baseinfo),
+                      function->expected_js_argc,
+                      args.length());
+        } else {
+            gjs_throw(context, "Too few arguments to function %s.%s: "
+                      "expected %d, got %" G_GSIZE_FORMAT,
+                      g_base_info_get_namespace(baseinfo),
+                      g_base_info_get_name(baseinfo),
+                      function->expected_js_argc,
+                      args.length());
+        }
         return false;
     }
 
diff --git a/installed-tests/js/testExceptions.js b/installed-tests/js/testExceptions.js
index d5fcd4b..595682e 100644
--- a/installed-tests/js/testExceptions.js
+++ b/installed-tests/js/testExceptions.js
@@ -172,3 +172,15 @@ describe('logError', function () {
         logError(new GLib.Error(GLib.quark_from_string('my-error'), 0, 'a message'), 'prefix');
     });
 });
+
+describe('Exception from function with too few arguments', function () {
+    it('contains the full function name', function () {
+        expect(() => GLib.get_locale_variants())
+            .toThrowError(/GLib\.get_locale_variants/);
+    });
+
+    it('contains the full method name', function () {
+        let file = Gio.File.new_for_path('foo');
+        expect(() => file.read()).toThrowError(/Gio\.File\.read/);
+    });
+});
\ No newline at end of file