Add endIndent property to Divider and VerticalDivider (#34057)

* Fixed indent to properly add to the top and not to the start

* Updated Divider documentation

packages/flutter/lib/src/material/divider.dart

@@ -13,15 +13,14 @@ import 'theme.dart';
 /// A one device pixel thick horizontal line, with padding on either
 /// side.
 ///
-/// In the material design language, this represents a divider.
+/// In the material design language, this represents a divider. Dividers can be
+/// used in lists, [Drawer]s, and elsewhere to separate content.
 ///
-/// Dividers can be used in lists, [Drawer]s, and elsewhere to separate content
-/// vertically or horizontally depending on the value of the [axis] enum.
-/// To create a one-pixel divider between items in a list, consider using
+/// To create a one-pixel divider between [ListTile] items, consider using
 /// [ListTile.divideTiles], which is optimized for this case.
 ///
 /// The box's total height is controlled by [height]. The appropriate
-/// padding is automatically computed from the width or height.
+/// padding is automatically computed from the height.
 ///
 /// See also:
 ///
@@ -36,6 +35,7 @@ class Divider extends StatelessWidget {
     Key key,
     this.height = 16.0,
     this.indent = 0.0,
+    this.endIndent = 0.0,
     this.color,
   }) : assert(height >= 0.0),
        super(key: key);
@@ -53,6 +53,9 @@ class Divider extends StatelessWidget {
   /// The amount of empty space to the left of the divider.
   final double indent;
 
+  /// The amount of empty space to the right of the divider.
+  final double endIndent;
+
   /// The color to use when painting the line.
   ///
   /// Defaults to the current theme's divider color, given by
@@ -108,7 +111,7 @@ class Divider extends StatelessWidget {
       child: Center(
         child: Container(
           height: 0.0,
-          margin: EdgeInsetsDirectional.only(start: indent),
+          margin: EdgeInsetsDirectional.only(start: indent, end: endIndent),
           decoration: BoxDecoration(
             border: Border(
               bottom: createBorderSide(context, color: color),
@@ -123,19 +126,16 @@ class Divider extends StatelessWidget {
 /// A one device pixel thick vertical line, with padding on either
 /// side.
 ///
-/// In the material design language, this represents a divider.
-///
-/// Dividers can be used in lists, [Drawer]s, and elsewhere to separate content
-/// horizontally. To create a one-pixel divider between items in a list,
-/// consider using [ListTile.divideTiles], which is optimized for this case.
+/// In the material design language, this represents a divider. Vertical
+/// dividers can be used in horizontally scrolling lists, such as a
+/// [ListView] with [ListView.scrollDirection] set to [Axis.horizontal].
 ///
 /// The box's total width is controlled by [width]. The appropriate
 /// padding is automatically computed from the width.
 ///
 /// See also:
 ///
-///  * [PopupMenuDivider], which is the equivalent but for popup menus.
-///  * [ListTile.divideTiles], another approach to dividing widgets in a list.
+///  * [ListView.separated], which can be used to generate vertical dividers.
 ///  * <https://material.io/design/components/dividers.html>
 class VerticalDivider extends StatelessWidget {
   /// Creates a material design divider.
@@ -145,6 +145,7 @@ class VerticalDivider extends StatelessWidget {
     Key key,
     this.width = 16.0,
     this.indent = 0.0,
+    this.endIndent = 0.0,
     this.color,
   }) : assert(width >= 0.0),
        super(key: key);
@@ -158,9 +159,12 @@ class VerticalDivider extends StatelessWidget {
   /// of exactly one device pixel, without any padding around it.
   final double width;
 
-  /// The amount of empty space to the left of the divider.
+  /// The amount of empty space on top of the divider.
   final double indent;
 
+  /// The amount of empty space under the divider.
+  final double endIndent;
+
   /// The color to use when painting the line.
   ///
   /// Defaults to the current theme's divider color, given by
@@ -183,7 +187,7 @@ class VerticalDivider extends StatelessWidget {
       child: Center(
         child: Container(
           width: 0.0,
-          margin: EdgeInsetsDirectional.only(start: indent),
+          margin: EdgeInsetsDirectional.only(top: indent, bottom: endIndent),
           decoration: BoxDecoration(
             border: Border(
               left: Divider.createBorderSide(context, color: color),

packages/flutter/test/material/divider_test.dart

@@ -22,6 +22,59 @@ void main() {
     expect(find.byType(Divider), paints..path(strokeWidth: 0.0));
   });
 
+  testWidgets('Horizontal divider custom indentation', (WidgetTester tester) async {
+    const double customIndent = 10.0;
+    Rect dividerRect;
+    Rect lineRect;
+
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: Divider(
+            indent: customIndent,
+          ),
+        ),
+      ),
+    );
+    // The divider line is drawn with a DecoratedBox with a border
+    dividerRect = tester.getRect(find.byType(Divider));
+    lineRect = tester.getRect(find.byType(DecoratedBox));
+    expect(lineRect.left, dividerRect.left + customIndent);
+    expect(lineRect.right, dividerRect.right);
+
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: Divider(
+            endIndent: customIndent,
+          ),
+        ),
+      ),
+    );
+    dividerRect = tester.getRect(find.byType(Divider));
+    lineRect = tester.getRect(find.byType(DecoratedBox));
+    expect(lineRect.left, dividerRect.left);
+    expect(lineRect.right, dividerRect.right - customIndent);
+
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: Divider(
+            indent: customIndent,
+            endIndent: customIndent,
+          ),
+        ),
+      ),
+    );
+    dividerRect = tester.getRect(find.byType(Divider));
+    lineRect = tester.getRect(find.byType(DecoratedBox));
+    expect(lineRect.left, dividerRect.left + customIndent);
+    expect(lineRect.right, dividerRect.right - customIndent);
+  });
+
   testWidgets('Vertical Divider Test', (WidgetTester tester) async {
     await tester.pumpWidget(
       const Directionality(
@@ -59,4 +112,57 @@ void main() {
     expect(containerBox.size.height, 600.0);
     expect(find.byType(VerticalDivider), paints..path(strokeWidth: 0.0));
   });
+
+  testWidgets('Vertical divider custom indentation', (WidgetTester tester) async {
+    const double customIndent = 10.0;
+    Rect dividerRect;
+    Rect lineRect;
+
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: VerticalDivider(
+            indent: customIndent,
+          ),
+        ),
+      ),
+    );
+    // The divider line is drawn with a DecoratedBox with a border
+    dividerRect = tester.getRect(find.byType(VerticalDivider));
+    lineRect = tester.getRect(find.byType(DecoratedBox));
+    expect(lineRect.top, dividerRect.top + customIndent);
+    expect(lineRect.bottom, dividerRect.bottom);
+
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: VerticalDivider(
+            endIndent: customIndent,
+          ),
+        ),
+      ),
+    );
+    dividerRect = tester.getRect(find.byType(VerticalDivider));
+    lineRect = tester.getRect(find.byType(DecoratedBox));
+    expect(lineRect.top, dividerRect.top);
+    expect(lineRect.bottom, dividerRect.bottom - customIndent);
+
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: Center(
+          child: VerticalDivider(
+            indent: customIndent,
+            endIndent: customIndent,
+          ),
+        ),
+      ),
+    );
+    dividerRect = tester.getRect(find.byType(VerticalDivider));
+    lineRect = tester.getRect(find.byType(DecoratedBox));
+    expect(lineRect.top, dividerRect.top + customIndent);
+    expect(lineRect.bottom, dividerRect.bottom - customIndent);
+  });
 }