Use singular Object.defineProperty if possible

If multiple properties are defined, we still use
`Object.defineProperties`. Else we now use `Object.defineProperty`.

Author: remcohaszing

fixtures/object-define-properties-reference/input.js

@@ -7,6 +7,12 @@ export default ((
   }
 ) =>
   ($0['assignment'] = Object.defineProperties($0, {
+    ['__proto__']: {
+      value: $0,
+      configurable: true,
+      enumerable: true,
+      writable: true
+    },
     configurable: {
       value: $0,
       configurable: true
@@ -18,6 +24,9 @@ export default ((
     writable: {
       value: $1,
       writable: true
+    },
+    [Symbol.for('global')]: {
+      value: {}
     }
   })))()
 

fixtures/object-define-properties/input.js

@@ -5,6 +5,10 @@ export default Object.defineProperties(
     string: 'Hello'
   },
   {
+    ['__proto__']: {
+      value: {},
+      configurable: true
+    },
     configurable: {
       value: 'Only configurable',
       configurable: true
@@ -16,6 +20,9 @@ export default Object.defineProperties(
     writable: {
       value: 'Only writable',
       writable: true
+    },
+    [Symbol.for('global')]: {
+      value: {}
     }
   }
 )
@@ -29,6 +36,10 @@ const withoutPreserveReferences = Object.defineProperties(
     string: 'Hello'
   },
   {
+    ['__proto__']: {
+      value: {},
+      configurable: true
+    },
     configurable: {
       value: 'Only configurable',
       configurable: true
@@ -40,6 +51,9 @@ const withoutPreserveReferences = Object.defineProperties(
     writable: {
       value: 'Only writable',
       writable: true
+    },
+    [Symbol.for('global')]: {
+      value: {}
     }
   }
 )

fixtures/object-define-property/input.js

@@ -0,0 +1,27 @@
+// Used as input
+// { preserveReferences: true }
+export default Object.defineProperty(
+  {
+    string: 'Hello',
+    ['__proto__']: {}
+  },
+  Symbol.for('global'),
+  {
+    value: ''
+  }
+)
+
+// -------------------------------------------------------------------------------------------------
+
+// Default output
+// { preserveReferences: false }
+const withoutPreserveReferences = Object.defineProperty(
+  {
+    string: 'Hello',
+    ['__proto__']: {}
+  },
+  Symbol.for('global'),
+  {
+    value: ''
+  }
+)

fixtures/object-proto-property-recursive/input.js

@@ -9,13 +9,11 @@ export default ((
     name: '$0'
   }
 ) => (
-  Object.defineProperties($1, {
-    ['__proto__']: {
-      value: $0,
-      configurable: true,
-      enumerable: true,
-      writable: true
-    }
+  Object.defineProperty($1, '__proto__', {
+    value: $0,
+    configurable: true,
+    enumerable: true,
+    writable: true
   }),
   $0
 ))()

src/estree-util-value-to-estree.ts

@@ -806,7 +806,7 @@ export function valueToEstree(value: unknown, options: Options = {}): Expression
     }
 
     const object = val as Record<string | symbol, unknown>
-    const propertyDescriptors: Property[] = []
+    const propertyDescriptors: [string | symbol, ObjectExpression][] = []
     for (const key of Reflect.ownKeys(val)) {
       // TODO [>=4] Throw an error for getters.
       const child = object[key]
@@ -823,29 +823,28 @@ export function valueToEstree(value: unknown, options: Options = {}): Expression
         if (writable) {
           propertyDescriptor.push(property('writable', literal(true)))
         }
-        propertyDescriptors.push(
-          property(key, {
-            type: 'ObjectExpression',
-            properties: propertyDescriptor
-          })
-        )
+        propertyDescriptors.push([
+          key,
+          { type: 'ObjectExpression', properties: propertyDescriptor }
+        ])
       } else if (
         context &&
         childContext &&
         namedContexts.indexOf(childContext) >= namedContexts.indexOf(context)
       ) {
         if (key === '__proto__') {
-          propertyDescriptors.push(
-            property(key, {
+          propertyDescriptors.push([
+            key,
+            {
               type: 'ObjectExpression',
               properties: [
                 property('value', generate(child)),
                 property('configurable', literal(true)),
                 property('enumerable', literal(true)),
                 property('writable', literal(true))
               ]
-            })
-          )
+            }
+          ])
         } else {
           childContext.assignment = {
             type: 'AssignmentExpression',
@@ -871,24 +870,29 @@ export function valueToEstree(value: unknown, options: Options = {}): Expression
     }
 
     if (propertyDescriptors.length) {
-      if (!context) {
-        return methodCall(identifier('Object'), 'defineProperties', [
-          objectExpression,
+      let name: string
+      let args: Expression[]
+
+      if (propertyDescriptors.length === 1) {
+        const [[key, expression]] = propertyDescriptors
+        name = 'defineProperty'
+        args = [typeof key === 'string' ? literal(key) : symbolToEstree(key), expression]
+      } else {
+        name = 'defineProperties'
+        args = [
           {
             type: 'ObjectExpression',
-            properties: propertyDescriptors
+            properties: propertyDescriptors.map(([key, expression]) => property(key, expression))
           }
-        ])
+        ]
+      }
+
+      if (!context) {
+        return methodCall(identifier('Object'), name, [objectExpression, ...args])
       }
 
       context.assignment = replaceAssignment(
-        methodCall(identifier('Object'), 'defineProperties', [
-          identifier(context.name!),
-          {
-            type: 'ObjectExpression',
-            properties: propertyDescriptors
-          }
-        ]),
+        methodCall(identifier('Object'), name, [identifier(context.name!), ...args]),
         context.assignment
       )
     }