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Merge pull request #1503 from ckeditor/t/1501

Internal: Introduced writer for manipulating non-semantic view. Closes #1501.
Szymon Cofalik hace 7 años
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+ 248 - 0
packages/ckeditor5-engine/src/view/upcastwriter.js

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+/**
+ * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+/**
+ * @module module:engine/view/upcastwriter
+ */
+
+import Element from './element';
+import { isPlainObject } from 'lodash-es';
+
+/**
+ * View upcast writer class. Provides set of methods used to properly manipulate nodes attached to
+ * {@link module:engine/view/view~View view instance}. It should be only used to manipulate non-semantic view
+ * (view created from HTML string). For view which was downcasted from the {@link module:engine/model/model~Model model}
+ * see {@link module:engine/view/downcastwriter~DowncastWriter downcast writer}.
+ */
+export default class UpcastWriter {
+	/**
+	 * Clones provided element.
+	 *
+	 * @see module:engine/view/element~Element#_clone
+	 * @param {module:engine/view/element~Element} element Element to be cloned.
+	 * @param {Boolean} [deep=false] If set to `true` clones element and all its children recursively. When set to `false`,
+	 * element will be cloned without any children.
+	 * @returns {module:engine/view/element~Element} Clone of this element.
+	 */
+	clone( element, deep = false ) {
+		return element._clone( deep );
+	}
+
+	/**
+	 * Appends a child node or a list of child nodes at the end of this node
+	 * and sets the parent of these nodes to this element.
+	 *
+	 * @see module:engine/view/element~Element#_appendChild
+	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
+	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
+	 * to which items will be appended.
+	 * @fires module:engine/view/node~Node#event:change
+	 * @returns {Number} Number of appended nodes.
+	 */
+	appendChild( items, element ) {
+		return element._appendChild( items );
+	}
+
+	/**
+	 * Inserts a child node or a list of child nodes on the given index and sets the parent of these nodes to
+	 * this element.
+	 *
+	 * @see module:engine/view/element~Element#_insertChild
+	 * @param {Number} index Offset at which nodes should be inserted.
+	 * @param {module:engine/view/item~Item|Iterable.<module:engine/view/item~Item>} items Items to be inserted.
+	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
+	 * to which items will be inserted.
+	 * @fires module:engine/view/node~Node#event:change
+	 * @returns {Number} Number of inserted nodes.
+	 */
+	insertChild( index, items, element ) {
+		return element._insertChild( index, items );
+	}
+
+	/**
+	 * Removes number of child nodes starting at the given index and set the parent of these nodes to `null`.
+	 *
+	 * @see module:engine/view/element~Element#_removeChildren
+	 * @param {Number} index Offset from which nodes will be removed.
+	 * @param {Number} howMany Number of nodes to remove.
+	 * @param {module:engine/view/element~Element|module:engine/view/documentfragment~DocumentFragment} element Element
+	 * which children will be removed.
+	 * @fires module:engine/view/node~Node#event:change
+	 * @returns {Array.<module:engine/view/node~Node>} The array containing removed nodes.
+	 */
+	removeChildren( index, howMany, element ) {
+		return element._removeChildren( index, howMany );
+	}
+
+	/**
+	 * Removes given element from the view structure. Will not have effect on detached elements.
+	 *
+	 * @param {module:engine/view/element~Element} element Element which will be removed.
+	 * @returns {Array.<module:engine/view/node~Node>} The array containing removed nodes.
+	 */
+	remove( element ) {
+		const parent = element.parent;
+
+		if ( parent ) {
+			return this.removeChildren( parent.getChildIndex( element ), 1, parent );
+		}
+
+		return [];
+	}
+
+	/**
+	 * Replaces given element with the new one in the view structure. Will not have effect on detached elements.
+	 *
+	 * @param {module:engine/view/element~Element} oldElement Element which will be replaced.
+	 * @param {module:engine/view/element~Element} newElement Element which will be inserted in the place of the old element.
+	 * @returns {Boolean} Whether old element was successfully replaced.
+	 */
+	replace( oldElement, newElement ) {
+		const parent = oldElement.parent;
+
+		if ( parent ) {
+			const index = parent.getChildIndex( oldElement );
+
+			this.removeChildren( index, 1, parent );
+			this.insertChild( index, newElement, parent );
+
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Renames element by creating a copy of a given element but with its name changed and then moving contents of the
+	 * old element to the new one.
+	 *
+	 * Since this function creates a new element and removes the given one, the new element is returned to keep reference.
+	 *
+	 * @param {String} newName New element name.
+	 * @param {module:engine/view/element~Element} element Element to be renamed.
+	 * @returns {module:engine/view/element~Element|null} New element or null if the old element
+	 * was not replaced (happens for detached elements).
+	 */
+	rename( newName, element ) {
+		const newElement = new Element( newName, element.getAttributes(), element.getChildren() );
+
+		return this.replace( element, newElement ) ? newElement : null;
+	}
+
+	/**
+	 * Adds or overwrites element's attribute with a specified key and value.
+	 *
+	 *		writer.setAttribute( linkElement, 'href', 'http://ckeditor.com' );
+	 *
+	 * @see module:engine/view/element~Element#_setAttribute
+	 * @param {String} key Attribute key.
+	 * @param {String} value Attribute value.
+	 * @param {module:engine/view/element~Element} element Element for which attribute will be set.
+	 */
+	setAttribute( key, value, element ) {
+		element._setAttribute( key, value );
+	}
+
+	/**
+	 * Removes attribute from the element.
+	 *
+	 *		writer.removeAttribute( linkElement, 'href' );
+	 *
+	 * @see module:engine/view/element~Element#_removeAttribute
+	 * @param {String} key Attribute key.
+	 * @param {module:engine/view/element~Element} element Element from which attribute will be removed.
+	 */
+	removeAttribute( key, element ) {
+		element._removeAttribute( key );
+	}
+
+	/**
+	 * Adds specified class to the element.
+	 *
+	 *		writer.addClass( linkElement, 'foo' );
+	 *		writer.addClass( linkElement, [ 'foo', 'bar' ] );
+	 *
+	 * @see module:engine/view/element~Element#_addClass
+	 * @param {Array.<String>|String} className Single class name or array of class names which will be added.
+	 * @param {module:engine/view/element~Element} element Element for which class will be added.
+	 */
+	addClass( className, element ) {
+		element._addClass( className );
+	}
+
+	/**
+	 * Removes specified class from the element.
+	 *
+	 *		writer.removeClass( linkElement, 'foo' );
+	 *		writer.removeClass( linkElement, [ 'foo', 'bar' ] );
+	 *
+	 * @see module:engine/view/element~Element#_removeClass
+	 * @param {Array.<String>|String} className Single class name or array of class names which will be removed.
+	 * @param {module:engine/view/element~Element} element Element from which class will be removed.
+	 */
+	removeClass( className, element ) {
+		element._removeClass( className );
+	}
+
+	/**
+	 * Adds style to the element.
+	 *
+	 *		writer.setStyle( element, 'color', 'red' );
+	 *		writer.setStyle( element, {
+	 *			color: 'red',
+	 *			position: 'fixed'
+	 *		} );
+	 *
+	 * @see module:engine/view/element~Element#_setStyle
+	 * @param {String|Object} property Property name or object with key - value pairs.
+	 * @param {String} [value] Value to set. This parameter is ignored if object is provided as the first parameter.
+	 * @param {module:engine/view/element~Element} element Element for which style will be added.
+	 */
+	setStyle( property, value, element ) {
+		if ( isPlainObject( property ) && element === undefined ) {
+			element = value;
+		}
+		element._setStyle( property, value );
+	}
+
+	/**
+	 * Removes specified style from the element.
+	 *
+	 *		writer.removeStyle( element, 'color' );  // Removes 'color' style.
+	 *		writer.removeStyle( element, [ 'color', 'border-top' ] ); // Removes both 'color' and 'border-top' styles.
+	 *
+	 * @see module:engine/view/element~Element#_removeStyle
+	 * @param {Array.<String>|String} property Style property name or names to be removed.
+	 * @param {module:engine/view/element~Element} element Element from which style will be removed.
+	 */
+	removeStyle( property, element ) {
+		element._removeStyle( property );
+	}
+
+	/**
+	 * Sets a custom property on element. Unlike attributes, custom properties are not rendered to the DOM,
+	 * so they can be used to add special data to elements.
+	 *
+	 * @see module:engine/view/element~Element#_setCustomProperty
+	 * @param {String|Symbol} key Custom property name/key.
+	 * @param {*} value Custom property value to be stored.
+	 * @param {module:engine/view/element~Element} element Element for which custom property will be set.
+	 */
+	setCustomProperty( key, value, element ) {
+		element._setCustomProperty( key, value );
+	}
+
+	/**
+	 * Removes a custom property stored under the given key.
+	 *
+	 * @see module:engine/view/element~Element#_removeCustomProperty
+	 * @param {String|Symbol} key Name/key of the custom property to be removed.
+	 * @param {module:engine/view/element~Element} element Element from which the custom property will be removed.
+	 * @returns {Boolean} Returns true if property was removed.
+	 */
+	removeCustomProperty( key, element ) {
+		return element._removeCustomProperty( key );
+	}
+}

+ 481 - 0
packages/ckeditor5-engine/tests/view/upcastwriter.js

@@ -0,0 +1,481 @@
+/**
+ * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import Element from '../../src/view/element';
+import UpcastWriter from '../../src/view/upcastwriter';
+import HtmlDataProcessor from '../../src/dataprocessor/htmldataprocessor';
+
+describe( 'UpcastWriter', () => {
+	let writer, view, dataprocessor;
+
+	before( () => {
+		writer = new UpcastWriter();
+		dataprocessor = new HtmlDataProcessor();
+	} );
+
+	beforeEach( () => {
+		const html = '' +
+			'<h1 style="color:blue;position:fixed;">Heading <strong>1</strong></h1>' +
+			'<p class="foo1 bar2" style="text-align:left;" data-attr="abc">Foo <i>Bar</i> <strong>Bold</strong></p>' +
+			'<p><u>Some underlined</u> text</p>' +
+			'<ul>' +
+			'<li class="single">Item 1</li>' +
+			'<li><span>Item <s>1</s></span></li>' +
+			'<li><h2>Item 1</h2></li>' +
+			'</ul>';
+
+		view = dataprocessor.toView( html );
+	} );
+
+	describe( 'clone', () => {
+		it( 'should clone simple element', () => {
+			const el = view.getChild( 0 );
+			const clone = writer.clone( el );
+
+			expect( clone ).to.not.equal( el );
+			expect( clone.isSimilar( el ) ).to.true;
+			expect( clone.childCount ).to.equal( 0 );
+		} );
+
+		it( 'should clone element with all attributes', () => {
+			const el = view.getChild( 1 );
+			const clone = writer.clone( el );
+
+			expect( clone ).to.not.equal( el );
+			expect( clone.isSimilar( el ) ).to.true;
+			expect( clone.childCount ).to.equal( 0 );
+		} );
+
+		it( 'should deep clone element', () => {
+			const el = view.getChild( 0 );
+			const clone = writer.clone( el, true );
+
+			expect( clone ).to.not.equal( el );
+			expect( clone.isSimilar( el ) ).to.true;
+			expect( clone.childCount ).to.equal( el.childCount );
+		} );
+	} );
+
+	describe( 'appendChild', () => {
+		it( 'should append inline child to paragraph', () => {
+			const el = view.getChild( 2 );
+			const newChild = new Element( 'span' );
+
+			const appended = writer.appendChild( newChild, el );
+
+			expect( appended ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.childCount ).to.equal( 3 );
+		} );
+
+		it( 'should append block children to paragraph', () => {
+			const el = view.getChild( 2 );
+			const newChild1 = new Element( 'p' );
+			const newChild2 = new Element( 'h2' );
+
+			const appended = writer.appendChild( [ newChild1, newChild2 ], el );
+
+			expect( appended ).to.equal( 2 );
+			expect( newChild1.parent ).to.equal( el );
+			expect( newChild2.parent ).to.equal( el );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should append list item to the list', () => {
+			const el = view.getChild( 3 );
+			const newChild = new Element( 'li' );
+
+			const appended = writer.appendChild( newChild, el );
+
+			expect( appended ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should append element to DocumentFragment element', () => {
+			const newChild = new Element( 'p' );
+
+			const appended = writer.appendChild( newChild, view );
+
+			expect( appended ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( view );
+			expect( view.childCount ).to.equal( 5 );
+		} );
+	} );
+
+	describe( 'insertChild', () => {
+		it( 'should insert inline child into the paragraph on the first position', () => {
+			const el = view.getChild( 2 );
+			const newChild = new Element( 'span' );
+
+			const inserted = writer.insertChild( 0, newChild, el );
+
+			expect( inserted ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.getChild( 0 ) ).to.equal( newChild );
+			expect( el.childCount ).to.equal( 3 );
+		} );
+
+		it( 'should insert block children into the paragraph on the last position', () => {
+			const el = view.getChild( 2 );
+			const newChild1 = new Element( 'blockquote' );
+			const newChild2 = new Element( 'h2' );
+
+			const inserted = writer.insertChild( 2, [ newChild1, newChild2 ], el );
+
+			expect( inserted ).to.equal( 2 );
+			expect( newChild1.parent ).to.equal( el );
+			expect( newChild2.parent ).to.equal( el );
+			expect( el.getChild( 2 ) ).to.equal( newChild1 );
+			expect( el.getChild( 3 ) ).to.equal( newChild2 );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should insert list item into the list element', () => {
+			const el = view.getChild( 3 );
+			const newChild = new Element( 'li' );
+
+			const inserted = writer.insertChild( 1, newChild, el );
+
+			expect( inserted ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( el );
+			expect( el.getChild( 1 ) ).to.equal( newChild );
+			expect( el.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should insert element to DocumentFragment element', () => {
+			const newChild = new Element( 'p' );
+
+			const inserted = writer.insertChild( 4, newChild, view );
+
+			expect( inserted ).to.equal( 1 );
+			expect( newChild.parent ).to.equal( view );
+			expect( view.getChild( 4 ) ).to.equal( newChild );
+			expect( view.childCount ).to.equal( 5 );
+		} );
+	} );
+
+	describe( 'removeChildren', () => {
+		it( 'should remove child from the beginning of the paragraph', () => {
+			const el = view.getChild( 1 );
+			const toRemove = el.getChild( 0 );
+
+			const removed = writer.removeChildren( 0, 1, el );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( el.childCount ).to.equal( 3 );
+		} );
+
+		it( 'should remove two last list items from the list element', () => {
+			const el = view.getChild( 3 );
+			const toRemove1 = el.getChild( 1 );
+			const toRemove2 = el.getChild( 2 );
+
+			const removed = writer.removeChildren( 1, 2, el );
+
+			expect( removed.length ).to.equal( 2 );
+			expect( removed[ 0 ] ).to.equal( toRemove1 );
+			expect( removed[ 1 ] ).to.equal( toRemove2 );
+			expect( el.childCount ).to.equal( 1 );
+		} );
+
+		it( 'should remove child from DocumentFragment element', () => {
+			const toRemove = view.getChild( 2 );
+
+			const removed = writer.removeChildren( 2, 1, view );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( view.childCount ).to.equal( 3 );
+		} );
+	} );
+
+	describe( 'remove', () => {
+		it( 'should remove list item from the list element', () => {
+			const toRemove = view.getChild( 3 ).getChild( 1 );
+
+			const removed = writer.remove( toRemove );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( view.getChild( 3 ).childCount ).to.equal( 2 );
+		} );
+
+		it( 'should have no effect on detached elements', () => {
+			const newChild = new Element( 'h2' );
+
+			const removed = writer.remove( newChild );
+
+			expect( removed.length ).to.equal( 0 );
+			expect( view.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should remove direct root (DocumentFragment) child', () => {
+			const toRemove = view.getChild( 3 );
+
+			const removed = writer.remove( toRemove );
+
+			expect( removed.length ).to.equal( 1 );
+			expect( removed[ 0 ] ).to.equal( toRemove );
+			expect( view.childCount ).to.equal( 3 );
+		} );
+	} );
+
+	describe( 'replace', () => {
+		it( 'should replace single element', () => {
+			const el = view.getChild( 0 ).getChild( 1 );
+			const newChild = new Element( 'span' );
+
+			const replacement = writer.replace( el, newChild );
+
+			expect( replacement ).to.true;
+			expect( view.getChild( 0 ).getChild( 1 ) ).to.equal( newChild );
+			expect( view.getChild( 0 ).childCount ).to.equal( 2 );
+		} );
+
+		it( 'should replace element with children', () => {
+			const el = view.getChild( 3 );
+			const newChild = new Element( 'ol' );
+
+			const replacement = writer.replace( el, newChild );
+
+			expect( replacement ).to.true;
+			expect( view.getChild( 3 ) ).to.equal( newChild );
+			expect( view.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should have no effect on detached elements', () => {
+			const oldChild = new Element( 'h2' );
+			const newChild = new Element( 'h2' );
+
+			const replacement = writer.replace( oldChild, newChild );
+
+			expect( replacement ).to.false;
+			expect( view.childCount ).to.equal( 4 );
+		} );
+	} );
+
+	describe( 'rename', () => {
+		it( 'should rename simple element', () => {
+			const el = view.getChild( 0 ).getChild( 1 );
+
+			const renamed = writer.rename( 'i', el );
+
+			expect( renamed ).to.not.equal( el );
+			expect( renamed ).to.equal( view.getChild( 0 ).getChild( 1 ) );
+			expect( renamed.name ).to.equal( 'i' );
+			expect( view.getChild( 0 ).childCount ).to.equal( 2 );
+		} );
+
+		it( 'should rename direct root (DocumentFragment) child element', () => {
+			const el = view.getChild( 1 );
+
+			const renamed = writer.rename( 'h3', el );
+
+			expect( renamed ).to.not.equal( el );
+			expect( renamed ).to.equal( view.getChild( 1 ) );
+			expect( renamed.name ).to.equal( 'h3' );
+			expect( view.childCount ).to.equal( 4 );
+		} );
+
+		it( 'should have no effect on detached element', () => {
+			const el = new Element( 'h2' );
+
+			const renamed = writer.rename( 'h3', el );
+
+			expect( renamed ).to.null;
+			expect( view.childCount ).to.equal( 4 );
+		} );
+	} );
+
+	describe( 'setAttribute', () => {
+		it( 'should add new attribute', () => {
+			const el = view.getChild( 0 );
+
+			writer.setAttribute( 'testAttr', 'testVal', el );
+
+			expect( el.getAttribute( 'testAttr' ) ).to.equal( 'testVal' );
+		} );
+
+		it( 'should update existing attribute', () => {
+			const el = view.getChild( 1 );
+
+			writer.setAttribute( 'data-attr', 'foo', el );
+
+			expect( el.getAttribute( 'data-attr' ) ).to.equal( 'foo' );
+		} );
+	} );
+
+	describe( 'removeAttribute', () => {
+		it( 'should remove existing attribute', () => {
+			const el = view.getChild( 1 );
+
+			writer.removeAttribute( 'data-attr', el );
+
+			expect( el.hasAttribute( 'data-attr' ) ).to.false;
+		} );
+
+		it( 'should have no effect if attribute does not exists', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeAttribute( 'non-existent', el );
+
+			expect( el.hasAttribute( 'non-existent' ) ).to.false;
+		} );
+	} );
+
+	describe( 'addClass', () => {
+		it( 'should add new classes if no classes', () => {
+			const el = view.getChild( 2 );
+
+			writer.addClass( [ 'foo', 'bar' ], el );
+
+			expect( el.hasClass( 'foo' ) ).to.true;
+			expect( el.hasClass( 'bar' ) ).to.true;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 2 );
+		} );
+
+		it( 'should add new class to existing classes', () => {
+			const el = view.getChild( 1 );
+
+			writer.addClass( 'newClass', el );
+
+			expect( el.hasClass( 'newClass' ) ).to.true;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 3 );
+		} );
+	} );
+
+	describe( 'removeClass', () => {
+		it( 'should remove existing class', () => {
+			const el = view.getChild( 3 ).getChild( 0 );
+
+			writer.removeClass( 'single', el );
+
+			expect( el.hasClass( 'single' ) ).to.false;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 0 );
+		} );
+
+		it( 'should remove existing class from many classes', () => {
+			const el = view.getChild( 1 );
+
+			writer.removeClass( 'foo1', el );
+
+			expect( el.hasClass( 'foo1' ) ).to.false;
+			expect( el.hasClass( 'bar2' ) ).to.true;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 1 );
+		} );
+
+		it( 'should have no effect if there are no classes', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeClass( 'non-existent', el );
+
+			expect( el.hasClass( 'non-existent' ) ).to.false;
+			expect( Array.from( el.getClassNames() ).length ).to.equal( 0 );
+		} );
+	} );
+
+	describe( 'setStyle', () => {
+		it( 'should add new style', () => {
+			const el = view.getChild( 2 );
+
+			writer.setStyle( {
+				color: 'red',
+				position: 'fixed'
+			}, el );
+
+			expect( el.getStyle( 'color' ) ).to.equal( 'red' );
+			expect( el.getStyle( 'position' ) ).to.equal( 'fixed' );
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 2 );
+		} );
+
+		it( 'should update existing styles', () => {
+			const el = view.getChild( 1 );
+
+			writer.setStyle( 'text-align', 'center', el );
+
+			expect( el.getStyle( 'text-align' ) ).to.equal( 'center' );
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 1 );
+		} );
+	} );
+
+	describe( 'removeStyle', () => {
+		it( 'should remove existing style', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeStyle( [ 'color', 'position' ], el );
+
+			expect( el.hasStyle( 'color' ) ).to.false;
+			expect( el.hasStyle( 'position' ) ).to.false;
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 0 );
+		} );
+
+		it( 'should remove value from existing styles', () => {
+			const el = view.getChild( 0 );
+
+			writer.removeStyle( 'position', el );
+
+			expect( el.hasStyle( 'color' ) ).to.true;
+			expect( el.hasStyle( 'position' ) ).to.false;
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 1 );
+		} );
+
+		it( 'should have no effect if styles does not exists', () => {
+			const el = view.getChild( 2 );
+
+			writer.removeStyle( [ 'color', 'position' ], el );
+
+			expect( el.hasStyle( 'color' ) ).to.false;
+			expect( el.hasStyle( 'position' ) ).to.false;
+			expect( Array.from( el.getStyleNames() ).length ).to.equal( 0 );
+		} );
+	} );
+
+	describe( 'setCustomProperty', () => {
+		it( 'should add or update custom property', () => {
+			const el = new Element( 'span' );
+
+			writer.setCustomProperty( 'prop1', 'foo', el );
+			writer.setCustomProperty( 'prop2', 'bar', el );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.equal( 'foo' );
+			expect( el.getCustomProperty( 'prop2' ) ).to.equal( 'bar' );
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 2 );
+
+			const objectProperty = { foo: 'bar' };
+			writer.setCustomProperty( 'prop2', objectProperty, el );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.equal( 'foo' );
+			expect( el.getCustomProperty( 'prop2' ) ).to.equal( objectProperty );
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 2 );
+		} );
+	} );
+
+	describe( 'removeCustomProperty', () => {
+		it( 'should remove existing custom property', () => {
+			const el = new Element( 'p' );
+
+			writer.setCustomProperty( 'prop1', 'foo', el );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.equal( 'foo' );
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 1 );
+
+			writer.removeCustomProperty( 'prop1', el );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.undefined;
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 0 );
+		} );
+
+		it( 'should have no effect if custom property does not exists', () => {
+			const el = new Element( 'h1' );
+
+			writer.removeCustomProperty( 'prop1', el );
+
+			expect( el.getCustomProperty( 'prop1' ) ).to.undefined;
+			expect( Array.from( el.getCustomProperties() ).length ).to.equal( 0 );
+		} );
+	} );
+} );