[Bugfix] Fix infinite recursion when emitting a named, implicit intersection schema (fix bcherny#309)

Author: bcherny

CONTRIBUTING.md

@@ -9,5 +9,5 @@
 - Add `export let only=true` to a test in test/e2e to just run that test
 - Add `export let exclude=true` to a test (or, add `.ignore` to its filename) in test/e2e to not run that test
 - To debug a test, with breakpoints:
-  1. Install [node-inspector](https://www.npmjs.com/package/node-inspector)
-  2. Run `node-debug ./node_modules/ava/profile.js ./dist/test/test.js`
+  1. Run `npm run pretest`
+  2. Follow the instructions [here](https://github.com/avajs/ava/blob/master/docs/recipes/debugging-with-vscode.md) for VSCode, [here](https://github.com/avajs/ava/blob/master/docs/recipes/debugging-with-webstorm.md) for Webstorm, or [here](https://github.com/avajs/ava/blob/master/docs/recipes/debugging-with-chrome-devtools.md) for Chrome Devtools

src/parser.ts

@@ -23,7 +23,7 @@ import {
   SchemaSchema,
   SchemaType
 } from './types/JSONSchema'
-import {generateName, log, maybeStripDefault} from './utils'
+import {generateName, log, maybeStripDefault, maybeStripNameHints} from './utils'
 
 export type Processed = Map<LinkedJSONSchema, Map<SchemaType, AST>>
 
@@ -66,7 +66,7 @@ export function parse(
   ast.params = types.map(type =>
     // We hoist description (for comment) and id/title (for standaloneName)
     // to the parent intersection type, so we remove it from the children.
-    parseAsTypeWithCache(omit(schema, 'description', 'id', 'title'), type, options, keyName, processed, usedNames)
+    parseAsTypeWithCache(maybeStripNameHints(schema), type, options, keyName, processed, usedNames)
   )
 
   log('blue', 'parser', 'Types:', types, 'Input:', schema, 'Output:', ast)

src/utils.ts

@@ -341,3 +341,23 @@ export function maybeStripDefault(schema: LinkedJSONSchema): LinkedJSONSchema {
   delete schema.default
   return schema
 }
+
+/**
+ * Removes the schema's `id`, `name`, and `description` properties
+ * if they exist.
+ * Useful when parsing intersections.
+ *
+ * Mutates `schema`.
+ */
+export function maybeStripNameHints(schema: JSONSchema): JSONSchema {
+  if ('description' in schema) {
+    delete schema.description
+  }
+  if ('id' in schema) {
+    delete schema.id
+  }
+  if ('name' in schema) {
+    delete schema.name
+  }
+  return schema
+}