feat(b-dropdown): add block support to toggle button (closes #4266) (#4269)

* feat(b-dropdown): add `block` support to toggle button

* Update README.md

* Update dropdown.spec.js

* Update README.md

Author: jacobmllr95

src/components/dropdown/README.md

@@ -308,6 +308,58 @@ split button its own variant via the `split-variant` prop.
 <!-- b-dropdown-split-variant.vue -->
 ```
 
+### Block level dropdowns
+
+By default dropdowns act like buttons and are displayed inline. To create block level dropdowns
+(that span to the full width of a parent) set the `block` prop. Both, regular and split button
+dropdowns are supported.
+
+```html
+<div>
+  <b-dropdown text="Block Level Dropdown" block variant="primary" class="m-2">
+    <b-dropdown-item href="#">Action</b-dropdown-item>
+    <b-dropdown-item href="#">Another action</b-dropdown-item>
+    <b-dropdown-item href="#">Something else here</b-dropdown-item>
+  </b-dropdown>
+
+  <b-dropdown
+    text="Block Level Split Dropdown"
+    block
+    split
+    split-variant="outline-primary"
+    variant="primary"
+    class="m-2"
+  >
+    <b-dropdown-item href="#">Action</b-dropdown-item>
+    <b-dropdown-item href="#">Another action</b-dropdown-item>
+    <b-dropdown-item href="#">Something else here...</b-dropdown-item>
+  </b-dropdown>
+</div>
+
+<!-- b-dropdown-block.vue -->
+```
+
+If you want the dropdown menu to span to the full width of the parent container too, add the `w-100`
+utility class to the `menu-class` prop.
+
+```html
+<div>
+  <b-dropdown
+    text="Block Level Dropdown Menu"
+    block
+    variant="primary"
+    class="m-2"
+    menu-class="w-100"
+  >
+    <b-dropdown-item href="#">Action</b-dropdown-item>
+    <b-dropdown-item href="#">Another action</b-dropdown-item>
+    <b-dropdown-item href="#">Something else here</b-dropdown-item>
+  </b-dropdown>
+</div>
+
+<!-- b-dropdown-block-menu.vue -->
+```
+
 ### Dropdown sub-component color variants
 
 Many of the supported dropdown [sub-components](#dropdown-supported-sub-components) provide a

src/components/dropdown/dropdown.js

@@ -24,6 +24,10 @@ export const props = {
     type: String,
     default: () => getComponentConfig(NAME, 'variant')
   },
+  block: {
+    type: Boolean,
+    default: false
+  },
   menuClass: {
     type: [String, Array],
     default: null
@@ -84,9 +88,16 @@ export const BDropdown = /*#__PURE__*/ Vue.extend({
         this.directionClass,
         {
           show: this.visible,
-          // Position `static` is needed to allow menu to "breakout" of the scrollParent boundaries
-          // when boundary is anything other than `scrollParent`
-          // See https://github.com/twbs/bootstrap/issues/24251#issuecomment-341413786
+          // The 'btn-group' class is required in `split` mode for button alignment
+          // It needs also to be applied when `block` is disabled to allow multiple
+          // dropdowns to be aligned one line
+          'btn-group': this.split || !this.block,
+          // When `block` is enabled and we are in `split` mode the 'd-flex' class
+          // needs to be applied to allow the buttons to stretch to full width
+          'd-flex': this.block && this.split,
+          // Position `static` is needed to allow menu to "breakout" of the `scrollParent`
+          // boundaries when boundary is anything other than `scrollParent`
+          // See: https://github.com/twbs/bootstrap/issues/24251#issuecomment-341413786
           'position-static': this.boundary !== 'scrollParent' || !this.boundary
         }
       ]
@@ -115,9 +126,10 @@ export const BDropdown = /*#__PURE__*/ Vue.extend({
     const buttonContent = this.normalizeSlot('button-content') || this.html || stripTags(this.text)
     if (this.split) {
       const btnProps = {
-        disabled: this.disabled,
         variant: this.splitVariant || this.variant,
-        size: this.size
+        size: this.size,
+        block: this.block,
+        disabled: this.disabled
       }
       // We add these as needed due to router-link issues with defined property with undefined/null values
       if (this.splitTo) {
@@ -149,10 +161,11 @@ export const BDropdown = /*#__PURE__*/ Vue.extend({
         staticClass: 'dropdown-toggle',
         class: this.toggleClasses,
         props: {
+          tag: this.toggleTag,
           variant: this.variant,
           size: this.size,
-          disabled: this.disabled,
-          tag: this.toggleTag
+          block: this.block && !this.split,
+          disabled: this.disabled
         },
         attrs: {
           id: this.safeId('_BV_toggle_'),
@@ -186,7 +199,7 @@ export const BDropdown = /*#__PURE__*/ Vue.extend({
     return h(
       'div',
       {
-        staticClass: 'dropdown btn-group b-dropdown',
+        staticClass: 'dropdown b-dropdown',
         class: this.dropdownClasses,
         attrs: { id: this.safeId() }
       },

src/components/dropdown/dropdown.spec.js

@@ -247,6 +247,30 @@ describe('dropdown', () => {
     wrapper.destroy()
   })
 
+  it('should not have "btn-group" class when block is true', async () => {
+    const wrapper = mount(BDropdown, {
+      attachToDocument: true,
+      propsData: {
+        block: true
+      }
+    })
+    expect(wrapper.classes()).not.toContain('btn-group')
+    wrapper.destroy()
+  })
+
+  it('should have "btn-group" and "d-flex" classes when block and split are true', async () => {
+    const wrapper = mount(BDropdown, {
+      attachToDocument: true,
+      propsData: {
+        block: true,
+        split: true
+      }
+    })
+    expect(wrapper.classes()).toContain('btn-group')
+    expect(wrapper.classes()).toContain('d-flex')
+    wrapper.destroy()
+  })
+
   it('should have "dropdown-toggle-no-caret" class when no-caret is true', async () => {
     const wrapper = mount(BDropdown, {
       attachToDocument: true,

src/components/dropdown/package.json

@@ -67,6 +67,10 @@
             "prop": "toggleClass",
             "description": "CSS class (or classes) to add to the toggle button"
           },
+          {
+            "prop": "block",
+            "description": "Renders a 100% width toggle button (expands to the width of it's parent container)"
+          },
           {
             "prop": "noCaret",
             "description": "Hide the caret indicator on the toggle button"