Factor out common code for collections in pretty-format (#4184)

* Factor out common code for collections in pretty-format

* Fix pretty lint error

* Improve comments and put printObjectProperties back together

packages/pretty-format/src/__tests__/asymmetric_matcher.test.js

@@ -196,7 +196,7 @@ describe(`indent option`, () => {
 
 describe(`maxDepth option`, () => {
   test(`matchers as leaf nodes`, () => {
-    options.maxDepth = 3;
+    options.maxDepth = 2;
     const val = {
       // ++depth === 1
       nested: [
@@ -229,7 +229,7 @@ describe(`maxDepth option`, () => {
 }`);
   });
   test(`matchers as internal nodes`, () => {
-    options.maxDepth = 3;
+    options.maxDepth = 2;
     const val = [
       // ++depth === 1
       expect.arrayContaining([

packages/pretty-format/src/collections.js

@@ -0,0 +1,192 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+
+import type {Config, Printer, Refs} from 'types/PrettyFormat';
+
+const getSymbols = Object.getOwnPropertySymbols || (obj => []);
+
+const isSymbol = key =>
+  // $FlowFixMe string literal `symbol`. This value is not a valid `typeof` return value
+  typeof key === 'symbol' || toString.call(key) === '[object Symbol]';
+
+// Return entries (for example, of a map)
+// with spacing, indentation, and comma
+// without surrounding punctuation (for example, braces)
+export function printIteratorEntries(
+  iterator: Iterator<[any, any]>,
+  config: Config,
+  indentation: string,
+  depth: number,
+  refs: Refs,
+  printer: Printer,
+  // Too bad, so sad that separator for ECMAScript Map has been ' => '
+  // What a distracting diff if you change a data structure to/from
+  // ECMAScript Object or Immutable.Map/OrderedMap which use the default.
+  separator: string = ': ',
+): string {
+  let result = '';
+  let current = iterator.next();
+
+  if (!current.done) {
+    result += config.spacingOuter;
+
+    const indentationNext = indentation + config.indent;
+
+    while (!current.done) {
+      const name = printer(
+        current.value[0],
+        config,
+        indentationNext,
+        depth,
+        refs,
+      );
+      const value = printer(
+        current.value[1],
+        config,
+        indentationNext,
+        depth,
+        refs,
+      );
+
+      result += indentationNext + name + separator + value;
+
+      current = iterator.next();
+
+      if (!current.done) {
+        result += ',' + config.spacingInner;
+      } else if (!config.min) {
+        result += ',';
+      }
+    }
+
+    result += config.spacingOuter + indentation;
+  }
+
+  return result;
+}
+
+// Return values (for example, of a set)
+// with spacing, indentation, and comma
+// without surrounding punctuation (braces or brackets)
+export function printIteratorValues(
+  iterator: Iterator<any>,
+  config: Config,
+  indentation: string,
+  depth: number,
+  refs: Refs,
+  printer: Printer,
+): string {
+  let result = '';
+  let current = iterator.next();
+
+  if (!current.done) {
+    result += config.spacingOuter;
+
+    const indentationNext = indentation + config.indent;
+
+    while (!current.done) {
+      result +=
+        indentationNext +
+        printer(current.value, config, indentationNext, depth, refs);
+
+      current = iterator.next();
+
+      if (!current.done) {
+        result += ',' + config.spacingInner;
+      } else if (!config.min) {
+        result += ',';
+      }
+    }
+
+    result += config.spacingOuter + indentation;
+  }
+
+  return result;
+}
+
+// Return items (for example, of an array)
+// with spacing, indentation, and comma
+// without surrounding punctuation (for example, brackets)
+export function printListItems(
+  list: any,
+  config: Config,
+  indentation: string,
+  depth: number,
+  refs: Refs,
+  printer: Printer,
+): string {
+  let result = '';
+
+  if (list.length) {
+    result += config.spacingOuter;
+
+    const indentationNext = indentation + config.indent;
+
+    for (let i = 0; i < list.length; i++) {
+      result +=
+        indentationNext +
+        printer(list[i], config, indentationNext, depth, refs);
+
+      if (i < list.length - 1) {
+        result += ',' + config.spacingInner;
+      } else if (!config.min) {
+        result += ',';
+      }
+    }
+
+    result += config.spacingOuter + indentation;
+  }
+
+  return result;
+}
+
+// Return properties of an object
+// with spacing, indentation, and comma
+// without surrounding punctuation (for example, braces)
+export function printObjectProperties(
+  val: Object,
+  config: Config,
+  indentation: string,
+  depth: number,
+  refs: Refs,
+  printer: Printer,
+): string {
+  let result = '';
+  let keys = Object.keys(val).sort();
+  const symbols = getSymbols(val);
+
+  if (symbols.length) {
+    keys = keys.filter(key => !isSymbol(key)).concat(symbols);
+  }
+
+  if (keys.length) {
+    result += config.spacingOuter;
+
+    const indentationNext = indentation + config.indent;
+
+    for (let i = 0; i < keys.length; i++) {
+      const key = keys[i];
+      const name = printer(key, config, indentationNext, depth, refs);
+      const value = printer(val[key], config, indentationNext, depth, refs);
+
+      result += indentationNext + name + ': ' + value;
+
+      if (i < keys.length - 1) {
+        result += ',' + config.spacingInner;
+      } else if (!config.min) {
+        result += ',';
+      }
+    }
+
+    result += config.spacingOuter + indentation;
+  }
+
+  return result;
+}