Divider: Improve default behavior when in vertical orientation

packages/components/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+### Enhancements
+
+-   `BaseControl`: Add `__nextHasNoMarginBottom` prop for opting into the new margin-free styles ([#39325](https://github.com/WordPress/gutenberg/pull/39325)).
+-   `Divider`: Make the divider visible by default (`display: inline`) in flow layout containers when the divider orientation is vertical ([#39316](https://github.com/WordPress/gutenberg/pull/39316)).
+
 ## 19.6.0 (2022-03-11)
 
 ### Enhancements
@@ -10,7 +15,6 @@
 -   `InputControl`: Allow `onBlur` for empty values to commit the change when `isPressEnterToChange` is true, and move reset behavior to the ESCAPE key. ([#39109](https://github.com/WordPress/gutenberg/pull/39109)).
 -   `TreeGrid`: Add tests for Home/End keyboard navigation. Add `onFocusRow` callback for Home/End keyboard navigation, this was missed in the implementation PR. Modify test for expanding/collapsing a row as row 1 implements this now. Update README with latest changes. ([#39302](https://github.com/WordPress/gutenberg/pull/39302))
 -   `ToggleGroupControlOption`: Calculate width from button content and remove `LabelPlaceholderView` ([#39345](https://github.com/WordPress/gutenberg/pull/39345))
--   `BaseControl`: Add `__nextHasNoMarginBottom` prop for opting into the new margin-free styles ([#39325](https://github.com/WordPress/gutenberg/pull/39325)).
 
 ### Bug Fix
 

packages/components/src/divider/stories/index.tsx

@@ -8,6 +8,7 @@ import type { ComponentMeta, ComponentStory } from '@storybook/react';
  */
 import { Text } from '../../text';
 import { Divider } from '..';
+import { Flex } from '../../flex';
 
 const meta: ComponentMeta< typeof Divider > = {
 	component: Divider,
@@ -30,41 +31,43 @@ const meta: ComponentMeta< typeof Divider > = {
 };
 export default meta;
 
-const HorizontalTemplate: ComponentStory< typeof Divider > = ( args ) => (
+const Template: ComponentStory< typeof Divider > = ( args ) => (
 	<div>
 		<Text>Some text before the divider</Text>
 		<Divider { ...args } />
 		<Text>Some text after the divider</Text>
 	</div>
 );
 
-const VerticalTemplate: ComponentStory< typeof Divider > = ( args ) => {
-	const styles = {
-		display: 'flex',
-		alignItems: 'stretch',
-		justifyContent: 'start',
-	};
-
-	return (
-		<div style={ styles }>
-			<Text>Some text before the divider</Text>
-			<Divider { ...args } />
-			<Text>Some text after the divider</Text>
-		</div>
-	);
-};
-
-export const Horizontal: ComponentStory<
-	typeof Divider
-> = HorizontalTemplate.bind( {} );
+export const Horizontal: ComponentStory< typeof Divider > = Template.bind( {} );
 Horizontal.args = {
 	margin: 2,
 };
 
-export const Vertical: ComponentStory< typeof Divider > = VerticalTemplate.bind(
-	{}
-);
+export const Vertical: ComponentStory< typeof Divider > = Template.bind( {} );
 Vertical.args = {
 	...Horizontal.args,
 	orientation: 'vertical',
 };
+
+// Inside a `flex` container, the divider will need to be `stretch` aligned in order to be visible.
+export const InFlexContainer: ComponentStory< typeof Divider > = ( args ) => {
+	return (
+		<Flex align="stretch">
+			<Text>
+				Some text before the divider Some text before the divider Some
+				text before the divider Some text before the divider Some text
+				before the divider Some text before the divider Some text before
+				the divider
+			</Text>
+			<Divider { ...args } />
+			<Text>
+				Some text after the divider Some text after the divider Some
+				text after the divider
+			</Text>
+		</Flex>
+	);
+};
+InFlexContainer.args = {
+	...Vertical.args,
+};

packages/components/src/divider/styles.ts

@@ -45,6 +45,14 @@ const renderMargin = ( {
 		} )()
 	);
 
+const renderDisplay = ( {
+	'aria-orientation': orientation = 'horizontal',
+}: Props ) => {
+	return orientation === 'vertical'
+		? css( { display: 'inline' } )
+		: undefined;
+};
+
 const renderBorder = ( {
 	'aria-orientation': orientation = 'horizontal',
 }: Props ) => {
@@ -67,6 +75,7 @@ export const DividerView = styled.hr< Props >`
 	border: 0;
 	margin: 0;
 
+	${ renderDisplay }
 	${ renderBorder }
 	${ renderSize }
 	${ renderMargin }

packages/components/src/divider/types.ts

@@ -22,8 +22,18 @@ export interface OwnProps {
 	 * Adjusts the inline-end margin.
 	 */
 	marginEnd?: SpaceInput;
+	/**
+	 * Divider's orientation. When using inside a flex container, you may need to make sure the divider is `stretch` aligned
+	 * in order for it to be visible.
+	 *
+	 * @default 'horizontal'
+	 */
+	orientation?: SeparatorProps[ 'orientation' ];
 }
 
 export interface Props
-	extends Omit< SeparatorProps, 'children' | 'unstable_system' >,
+	extends Omit<
+			SeparatorProps,
+			'children' | 'unstable_system' | 'orientation'
+		>,
 		OwnProps {}