pkg/(unit)test: include a copy of old matcher

lib/src/matcher/pretty_print.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library unittest.matcher.pretty_print;
+
+import 'description.dart';
+import 'interfaces.dart';
+import 'util.dart';
+
+/// Returns a pretty-printed representation of [object].
+///
+/// If [maxLineLength] is passed, this will attempt to ensure that each line is
+/// no longer than [maxLineLength] characters long. This isn't guaranteed, since
+/// individual objects may have string representations that are too long, but
+/// most lines will be less than [maxLineLength] long.
+///
+/// If [maxItems] is passed, [Iterable]s and [Map]s will only print their first
+/// [maxItems] members or key/value pairs, respectively.
+String prettyPrint(object, {int maxLineLength, int maxItems}) {
+  String _prettyPrint(object, int indent, Set seen, bool top) {
+    // If the object is a matcher, use its description.
+    if (object is Matcher) {
+      var description = new StringDescription();
+      object.describe(description);
+      return "<$description>";
+    }
+
+    // Avoid looping infinitely on recursively-nested data structures.
+    if (seen.contains(object)) return "(recursive)";
+    seen = seen.union(new Set.from([object]));
+    String pp(child) => _prettyPrint(child, indent + 2, seen, false);
+
+    if (object is Iterable) {
+      // Print the type name for non-List iterables.
+      var type = object is List ? "" : _typeName(object) + ":";
+
+      // Truncate the list of strings if it's longer than [maxItems].
+      var strings = object.map(pp).toList();
+      if (maxItems != null && strings.length > maxItems) {
+        strings.replaceRange(maxItems - 1, strings.length, ['...']);
+      }
+
+      // If the printed string is short and doesn't contain a newline, print it
+      // as a single line.
+      var singleLine = "$type[${strings.join(', ')}]";
+      if ((maxLineLength == null ||
+              singleLine.length + indent <= maxLineLength) &&
+          !singleLine.contains("\n")) {
+        return singleLine;
+      }
+
+      // Otherwise, print each member on its own line.
+      return "$type[\n" + strings.map((string) {
+        return _indent(indent + 2) + string;
+      }).join(",\n") + "\n" + _indent(indent) + "]";
+    } else if (object is Map) {
+      // Convert the contents of the map to string representations.
+      var strings = object.keys.map((key) {
+        return '${pp(key)}: ${pp(object[key])}';
+      }).toList();
+
+      // Truncate the list of strings if it's longer than [maxItems].
+      if (maxItems != null && strings.length > maxItems) {
+        strings.replaceRange(maxItems - 1, strings.length, ['...']);
+      }
+
+      // If the printed string is short and doesn't contain a newline, print it
+      // as a single line.
+      var singleLine = "{${strings.join(", ")}}";
+      if ((maxLineLength == null ||
+              singleLine.length + indent <= maxLineLength) &&
+          !singleLine.contains("\n")) {
+        return singleLine;
+      }
+
+      // Otherwise, print each key/value pair on its own line.
+      return "{\n" + strings.map((string) {
+        return _indent(indent + 2) + string;
+      }).join(",\n") + "\n" + _indent(indent) + "}";
+    } else if (object is String) {
+      // Escape strings and print each line on its own line.
+      var lines = object.split("\n");
+      return "'" +
+          lines.map(_escapeString).join("\\n'\n${_indent(indent + 2)}'") +
+          "'";
+    } else {
+      var value = object.toString().replaceAll("\n", _indent(indent) + "\n");
+      var defaultToString = value.startsWith("Instance of ");
+
+      // If this is the top-level call to [prettyPrint], wrap the value on angle
+      // brackets to set it apart visually.
+      if (top) value = "<$value>";
+
+      // Print the type of objects with custom [toString] methods. Primitive
+      // objects and objects that don't implement a custom [toString] don't need
+      // to have their types printed.
+      if (object is num ||
+          object is bool ||
+          object is Function ||
+          object == null ||
+          defaultToString) {
+        return value;
+      } else {
+        return "${_typeName(object)}:$value";
+      }
+    }
+  }
+
+  return _prettyPrint(object, 0, new Set(), true);
+}
+
+String _indent(int length) => new List.filled(length, ' ').join('');
+
+/// Returns the name of the type of [x], or "Unknown" if the type name can't be
+/// determined.
+String _typeName(x) {
+  // dart2js blows up on some objects (e.g. window.navigator).
+  // So we play safe here.
+  try {
+    if (x == null) return "null";
+    var type = x.runtimeType.toString();
+    // TODO(nweiz): if the object's type is private, find a public superclass to
+    // display once there's a portable API to do that.
+    return type.startsWith("_") ? "?" : type;
+  } catch (e) {
+    return "?";
+  }
+}
+
+/// Returns [source] with any control characters replaced by their escape
+/// sequences.
+///
+/// This doesn't add quotes to the string, but it does escape single quote
+/// characters so that single quotes can be applied externally.
+String _escapeString(String source) => escape(source).replaceAll("'", r"\'");