Fix BorderSide rendering (#7705)

packages/flutter/lib/src/painting/box_painter.dart

@@ -433,7 +433,7 @@ class Border {
         path = new Path();
         path.moveTo(rect.left, rect.bottom);
         path.lineTo(rect.left, rect.top);
-        if (right.width == 0.0) {
+        if (left.width == 0.0) {
           paint.style = PaintingStyle.stroke;
         } else {
           paint.style = PaintingStyle.fill;

packages/flutter/test/widgets/box_decoration_test.dart

@@ -6,6 +6,8 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 
+import '../rendering/mock_canvas.dart';
+
 void main() {
   testWidgets('Circles can have uniform borders', (WidgetTester tester) async {
     await tester.pumpWidget(
@@ -36,4 +38,52 @@ void main() {
     );
     expect(tester.getSize(find.byKey(key)), equals(const Size(45.0, 45.0)));
   });
+
+  testWidgets('BoxDecoration paints its border correctly', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/7672
+
+    final Key key = new Key('Container with BoxDecoration');
+    Widget buildFrame(Border border) {
+      return new Center(
+        child: new Container(
+          key: key,
+          width: 100.0,
+          height: 50.0,
+          decoration: new BoxDecoration(border: border),
+        ),
+      );
+    }
+
+    final Color black = const Color(0xFF000000);
+
+    await tester.pumpWidget(buildFrame(new Border.all()));
+    expect(find.byKey(key), paints
+      ..path(color: black, style: PaintingStyle.fill)
+      ..path(color: black, style: PaintingStyle.fill)
+      ..path(color: black, style: PaintingStyle.fill)
+      ..path(color: black, style: PaintingStyle.fill));
+
+    await tester.pumpWidget(buildFrame(new Border.all(width: 0.0)));
+    expect(find.byKey(key), paints
+      ..path(color: black, style: PaintingStyle.stroke)
+      ..path(color: black, style: PaintingStyle.stroke)
+      ..path(color: black, style: PaintingStyle.stroke)
+      ..path(color: black, style: PaintingStyle.stroke));
+
+    final Color green = const Color(0xFF000000);
+    final BorderSide greenSide = new BorderSide(color: green, width: 10.0);
+
+    await tester.pumpWidget(buildFrame(new Border(top: greenSide)));
+    expect(find.byKey(key), paints..path(color: green, style: PaintingStyle.fill));
+
+    await tester.pumpWidget(buildFrame(new Border(left: greenSide)));
+    expect(find.byKey(key), paints..path(color: green, style: PaintingStyle.fill));
+
+    await tester.pumpWidget(buildFrame(new Border(right: greenSide)));
+    expect(find.byKey(key), paints..path(color: green, style: PaintingStyle.fill));
+
+    await tester.pumpWidget(buildFrame(new Border(bottom: greenSide)));
+    expect(find.byKey(key), paints..path(color: green, style: PaintingStyle.fill));
+  });
+
 }