Config - Support additionalProperties field of object schemas

spec/config-spec.coffee

@@ -1429,6 +1429,47 @@ describe "Config", ->
           expect(atom.config.get('foo.bar.anInt')).toEqual 12
           expect(atom.config.get('foo.bar.nestedObject.nestedBool')).toEqual true
 
+        describe "when the value has additionalProperties set to false", ->
+          it 'does not allow other properties to be set on the object', ->
+            atom.config.setSchema('foo.bar',
+              type: 'object'
+              properties:
+                anInt:
+                  type: 'integer'
+                  default: 12
+              additionalProperties: false
+            )
+
+            expect(atom.config.set('foo.bar', {anInt: 5, somethingElse: 'ok'})).toBe true
+            expect(atom.config.get('foo.bar.anInt')).toBe 5
+            expect(atom.config.get('foo.bar.somethingElse')).toBeUndefined()
+
+            expect(atom.config.set('foo.bar.somethingElse', {anInt: 5})).toBe false
+            expect(atom.config.get('foo.bar.somethingElse')).toBeUndefined()
+
+        describe 'when the value has an additionalProperties schema', ->
+          it 'validates properties of the object against that schema', ->
+            atom.config.setSchema('foo.bar',
+              type: 'object'
+              properties:
+                anInt:
+                  type: 'integer'
+                  default: 12
+              additionalProperties:
+                type: 'string'
+            )
+
+            expect(atom.config.set('foo.bar', {anInt: 5, somethingElse: 'ok'})).toBe true
+            expect(atom.config.get('foo.bar.anInt')).toBe 5
+            expect(atom.config.get('foo.bar.somethingElse')).toBe 'ok'
+
+            expect(atom.config.set('foo.bar.somethingElse', 7)).toBe false
+            expect(atom.config.get('foo.bar.somethingElse')).toBe 'ok'
+
+            expect(atom.config.set('foo.bar', {anInt: 6, somethingElse: 7})).toBe true
+            expect(atom.config.get('foo.bar.anInt')).toBe 6
+            expect(atom.config.get('foo.bar.somethingElse')).toBe undefined
+
       describe 'when the value has an "array" type', ->
         beforeEach ->
           schema =

src/config.coffee

@@ -673,7 +673,12 @@ class Config
       if schema.type is 'object'
         childSchema = schema.properties?[key]
         unless childSchema?
-          return null
+          if isPlainObject(schema.additionalProperties)
+            childSchema = schema.additionalProperties
+          else if schema.additionalProperties is false
+            return false
+          else
+            return null
       else
         return false
       schema = childSchema
@@ -1085,17 +1090,26 @@ Config.addSchemaEnforcers
       throw new Error("Validation failed at #{keyPath}, #{JSON.stringify(value)} must be an object") unless isPlainObject(value)
       return value unless schema.properties?
 
+      defaultChildSchema = null
+      allowsAdditionalProperties = true
+      if isPlainObject(schema.additionalProperties)
+        defaultChildSchema = schema.additionalProperties
+      if schema.additionalProperties is false
+        allowsAdditionalProperties = false
+
       newValue = {}
       for prop, propValue of value
-        childSchema = schema.properties[prop]
+        childSchema = schema.properties[prop] ? defaultChildSchema
         if childSchema?
           try
             newValue[prop] = @executeSchemaEnforcers("#{keyPath}.#{prop}", propValue, childSchema)
           catch error
             console.warn "Error setting item in object: #{error.message}"
-        else
+        else if allowsAdditionalProperties
           # Just pass through un-schema'd values
           newValue[prop] = propValue
+        else
+          console.warn "Illegal object key: #{keyPath}.#{prop}"
 
       newValue