Reviewers: mp+218195_code.launchpad.net,

Message:
Please take a look.

Description:
Allow charm with empty peers, provides, requires.

In the case that a null was read in for the maps, use
an empty map instead of throwing error. Added test case
to show error.  Bug #1313793

https://code.launchpad.net/~jimmiebtlr/juju-core/fix-no-peers-charm/+merge/218195

(do not edit description out of merge proposal)


Please review this at https://codereview.appspot.com/98410043/

Affected files (+42, -8 lines):
   A [revision details]
   M charm/meta_test.go
   M schema/schema.go
   M schema/schema_test.go
   A testing/repo/quantal/empty-fields/metadata.yaml


Index: [revision details]
=== added file '[revision details]'
--- [revision details]	2012-01-01 00:00:00 +0000
+++ [revision details]	2012-01-01 00:00:00 +0000
@@ -0,0 +1,2 @@
+Old revision: tarmac-20140520024339-qids5ewddm0js4yq
+New revision: <email address hidden>

Index: charm/meta_test.go
=== modified file 'charm/meta_test.go'
--- charm/meta_test.go	2014-04-09 16:36:12 +0000
+++ charm/meta_test.go	2014-05-20 03:20:37 +0000
@@ -161,6 +161,12 @@
  		Scope:     charm.ScopeGlobal,
  	})
  	c.Assert(meta.Peers, gc.IsNil)
+
+	meta, err = charm.ReadMeta(repoMeta("empty-fields"))
+	c.Assert(meta.Provides, gc.DeepEquals, map[string]charm.Relation{})
+	c.Assert(meta.Requires, gc.DeepEquals, map[string]charm.Relation{})
+	c.Assert(meta.Peers, gc.DeepEquals, map[string]charm.Relation{})
+	c.Assert(err, gc.IsNil)
  }

  var relationsConstraintsTests = []struct {


Index: schema/schema.go
=== modified file 'schema/schema.go'
--- schema/schema.go	2014-01-15 10:50:11 +0000
+++ schema/schema.go	2014-05-20 03:20:37 +0000
@@ -293,6 +293,11 @@

  func (c mapC) Coerce(v interface{}, path []string) (interface{}, error) {
  	rv := reflect.ValueOf(v)
+
+	// handles case where map is empty
+	if rv.Kind() == reflect.Invalid {
+		return make(map[interface{}]interface{}), nil
+	}
  	if rv.Kind() != reflect.Map {
  		return nil, error_{"map", v, path}
  	}
@@ -334,6 +339,11 @@

  func (c stringMapC) Coerce(v interface{}, path []string) (interface{},  
error) {
  	rv := reflect.ValueOf(v)
+
+	// treat nil value as empty map
+	if rv.Kind() == reflect.Invalid {
+		return make(map[string]interface{}), nil
+	}
  	if rv.Kind() != reflect.Map {
  		return nil, error_{"map", v, path}
  	}
@@ -399,6 +409,11 @@

  func (c fieldMapC) Coerce(v interface{}, path []string) (interface{},  
error) {
  	rv := reflect.ValueOf(v)
+
+	// treat nil value as empty map
+	if rv.Kind() == reflect.Invalid {
+		return make(map[string]interface{}), nil
+	}
  	if rv.Kind() != reflect.Map {
  		return nil, error_{"map", v, path}
  	}
@@ -488,6 +503,11 @@

  func (c mapSetC) Coerce(v interface{}, path []string) (interface{}, error)  
{
  	rv := reflect.ValueOf(v)
+
+	// treat nil value as empty map
+	if rv.Kind() == reflect.Invalid {
+		return make(map[string]interface{}), nil
+	}
  	if rv.Kind() != reflect.Map {
  		return nil, error_{"map", v, path}
  	}


Index: schema/schema_test.go
=== modified file 'schema/schema_test.go'
--- schema/schema_test.go	2014-01-14 13:10:26 +0000
+++ schema/schema_test.go	2014-05-20 03:20:37 +0000
@@ -250,8 +250,8 @@
  	c.Assert(err, gc.ErrorMatches, "<path>: expected map, got int\\(42\\)")

  	out, err = sch.Coerce(nil, aPath)
-	c.Assert(out, gc.IsNil)
-	c.Assert(err, gc.ErrorMatches, "<path>: expected map, got nothing")
+	c.Assert(out, gc.DeepEquals, map[interface{}]interface{}{})
+	c.Assert(err, gc.IsNil)

  	out, err = sch.Coerce(map[int]int{1: 1}, aPath)
  	c.Assert(out, gc.IsNil)
@@ -278,8 +278,8 @@
  	c.Assert(err, gc.ErrorMatches, "<path>: expected map, got int\\(42\\)")

  	out, err = sch.Coerce(nil, aPath)
-	c.Assert(out, gc.IsNil)
-	c.Assert(err, gc.ErrorMatches, "<path>: expected map, got nothing")
+	c.Assert(out, gc.DeepEquals, map[string]interface{}{})
+	c.Assert(err, gc.IsNil)

  	out, err = sch.Coerce(map[int]int{1: 1}, aPath)
  	c.Assert(out, gc.IsNil)
@@ -306,8 +306,8 @@
  	c.Assert(err, gc.ErrorMatches, "<path>: expected map, got int\\(42\\)")

  	out, err = sch.Coerce(nil, aPath)
-	c.Assert(out, gc.IsNil)
-	c.Assert(err, gc.ErrorMatches, "<path>: expected map, got nothing")
+	c.Assert(out, gc.DeepEquals, map[string]interface{}{})
+	c.Assert(err, gc.IsNil)

  	out, err = sch.Coerce(map[string]interface{}{"a": "A", "b": "C"}, aPath)
  	c.Assert(out, gc.IsNil)
@@ -416,8 +416,8 @@
  	c.Assert(err, gc.ErrorMatches, `<path>: expected map, got int\(42\)`)

  	out, err = sch.Coerce(nil, aPath)
-	c.Assert(out, gc.IsNil)
-	c.Assert(err, gc.ErrorMatches, `<path>: expected map, got nothing`)
+	c.Assert(out, gc.DeepEquals, map[string]interface{}{})
+	c.Assert(err, gc.IsNil)

  	// First path entry shouldn't have dots in an error message.
  	out, err = sch.Coerce(map[string]int{"a": 1}, nil)


Index: testing/repo/quantal/empty-fields/metadata.yaml
=== added file 'testing/repo/quantal/empty-fields/metadata.yaml'
--- testing/repo/quantal/empty-fields/metadata.yaml	1970-01-01 00:00:00  
+0000
+++ testing/repo/quantal/empty-fields/metadata.yaml	2014-05-03 17:48:01  
+0000
@@ -0,0 +1,6 @@
+name: empty-fields
+summary: "Kerosene powered blender"
+description: "Description here"
+provides:
+peers:
+requires: