diff --git a/packages/dom/package.json b/packages/dom/package.json index 407cac0..9c80533 100644 --- a/packages/dom/package.json +++ b/packages/dom/package.json @@ -35,6 +35,7 @@ "test": "NODE_ENV=test mocha" }, "dependencies": { + "@adobe/css-tools": "^4.4.3", "fast-deep-equal": "^3.1.3", "tslib": "^2.6.2" }, diff --git a/packages/dom/src/lib/ElementAssertion.ts b/packages/dom/src/lib/ElementAssertion.ts index 537d808..c4fc8a6 100644 --- a/packages/dom/src/lib/ElementAssertion.ts +++ b/packages/dom/src/lib/ElementAssertion.ts @@ -1,4 +1,7 @@ import { Assertion, AssertionError } from "@assertive-ts/core"; +import equal from "fast-deep-equal"; + +import { getReceivedStyle, normalizeStyles } from "./helpers/helpers"; export class ElementAssertion extends Assertion { @@ -142,9 +145,50 @@ export class ElementAssertion extends Assertion { ); } - private getClassList(): string[] { - return this.actual.className.split(/\s+/).filter(Boolean); - } + /** + * Asserts that the element has the specified CSS styles. + * + * @example + * ``` + * expect(component).toHaveStyle({ color: 'green', display: 'block' }); + * ``` + * + * @param expected the expected CSS styles. + * @returns the assertion instance. + */ + + public toHaveStyle(expected: Partial): this { + if (!this.actual.ownerDocument.defaultView) { + throw new Error("The element is not attached to a document with a default view."); + } + if (!(this.actual instanceof HTMLElement)) { + throw new Error("The element is not an HTMLElement."); + } + + const window = this.actual.ownerDocument.defaultView; + + const received = window.getComputedStyle(this.actual); + + const { props, expectedStyle } = normalizeStyles(expected); + + const receivedStyle = getReceivedStyle(props, received); + + const error = new AssertionError({ + actual: this.actual, + expected: expectedStyle, + message: `Expected the element to match the following style:\n${JSON.stringify(expectedStyle, null, 2)}`, + }); + const invertedError = new AssertionError({ + actual: this.actual, + message: `Expected the element to NOT match the following style:\n${JSON.stringify(expectedStyle, null, 2)}`, + }); + + return this.execute({ + assertWhen: equal(expectedStyle, receivedStyle), + error, + invertedError, + }); + } /** * Helper method to assert the presence or absence of class names. @@ -181,4 +225,8 @@ export class ElementAssertion extends Assertion { invertedError, }); } + + private getClassList(): string[] { + return this.actual.className.split(/\s+/).filter(Boolean); + } } diff --git a/packages/dom/src/lib/helpers/helpers.ts b/packages/dom/src/lib/helpers/helpers.ts new file mode 100644 index 0000000..843be7d --- /dev/null +++ b/packages/dom/src/lib/helpers/helpers.ts @@ -0,0 +1,56 @@ +export interface CssAtRuleAST { + declarations: StyleDeclaration[]; + rules: Rule[]; +} + +interface Rule { + declarations: StyleDeclaration[]; + selectors: string[]; +} + +interface StyleDeclaration extends Record { + property: string; + value: string; +} + +export const normalizeStyles = (css: Partial): +{ expectedStyle: StyleDeclaration; props: string[]; } => { + const normalizer = document.createElement("div"); + document.body.appendChild(normalizer); + + const { props, expectedStyle } = Object.entries(css).reduce( + (acc, [property, value]) => { + + if (typeof value !== "string") { + return acc; + } + + normalizer.style.setProperty(property, value); + + const normalizedValue = window + .getComputedStyle(normalizer) + .getPropertyValue(property) + .trim(); + + return { + expectedStyle: { + ...acc.expectedStyle, + [property]: normalizedValue, + }, + props: [...acc.props, property], + }; + }, + { expectedStyle: {} as StyleDeclaration, props: [] as string[] }, + ); + + document.body.removeChild(normalizer); + + return { expectedStyle, props }; +}; + +export const getReceivedStyle = (props: string[], received: CSSStyleDeclaration): StyleDeclaration => { + return props.reduce((acc, prop) => { + acc[prop] = received?.getPropertyValue(prop).trim(); + return acc; + }, {} as StyleDeclaration); +}; diff --git a/packages/dom/test/unit/lib/ElementAssertion.test.tsx b/packages/dom/test/unit/lib/ElementAssertion.test.tsx index 47bb167..f91f10c 100644 --- a/packages/dom/test/unit/lib/ElementAssertion.test.tsx +++ b/packages/dom/test/unit/lib/ElementAssertion.test.tsx @@ -257,12 +257,84 @@ describe("[Unit] ElementAssertion.test.ts", () => { const test = new ElementAssertion(divTest); expect(() => test.toHaveAllClasses("foo", "bar", "baz")) - .toThrowError(AssertionError) - .toHaveMessage('Expected the element to have all of these classes: "foo bar baz"'); + .toThrowError(AssertionError) + .toHaveMessage('Expected the element to have all of these classes: "foo bar baz"'); expect(test.not.toHaveAllClasses("foo", "bar", "baz")).toBeEqual(test); }); }); }); + describe(".toHaveStyle", () => { + context("when the element has the expected style", () => { + it("returns the assertion instance", () => { + const { getByTestId } = render( +
); + const divTest = getByTestId("test-div"); + const test = new ElementAssertion(divTest); + + expect(test.toHaveStyle({ border: "1px solid black", color: "red", display: "flex" })).toBeEqual(test); + + expect(() => test.not.toHaveStyle({ border: "1px solid black", color: "red", display: "flex" })) + .toThrowError(AssertionError) + .toHaveMessage( + // eslint-disable-next-line max-len + 'Expected the element to NOT match the following style:\n{\n "border": "1px solid black",\n "color": "rgb(255, 0, 0)",\n "display": "flex"\n}', + ); + }); + }); + + context("when the element does not have the expected style", () => { + it("throws an assertion error", () => { + const { getByTestId } = render( +
, + ); + + const divTest = getByTestId("test-div"); + const test = new ElementAssertion(divTest); + + expect(() => test.toHaveStyle(({ border: "1px solid black", color: "red", display: "flex" }))) + .toThrowError(AssertionError) + .toHaveMessage( + // eslint-disable-next-line max-len + 'Expected the element to match the following style:\n{\n "border": "1px solid black",\n "color": "rgb(255, 0, 0)",\n "display": "flex"\n}', + ); + + expect(test.not.toHaveStyle({ border: "1px solid black", color: "red", display: "flex" })).toBeEqual(test); + + }); + }); + context("when the element partially match the style", () => { + it("throws an assertion error", () => { + const { getByTestId } = render( +
, + ); + + const divTest = getByTestId("test-div"); + const test = new ElementAssertion(divTest); + + expect(() => test.toHaveStyle(({ color: "red", display: "flex" }))) + .toThrowError(AssertionError) + .toHaveMessage( + // eslint-disable-next-line max-len + 'Expected the element to match the following style:\n{\n "color": "rgb(255, 0, 0)",\n "display": "flex"\n}', + ); + + expect(test.not.toHaveStyle({ border: "1px solid black", color: "red", display: "flex" })).toBeEqual(test); + + }); + }); + }); }); diff --git a/yarn.lock b/yarn.lock index 6d0e447..d0f35ba 100644 --- a/yarn.lock +++ b/yarn.lock @@ -12,6 +12,13 @@ __metadata: languageName: node linkType: hard +"@adobe/css-tools@npm:^4.4.3": + version: 4.4.3 + resolution: "@adobe/css-tools@npm:4.4.3" + checksum: 10/701379c514b7a43ca6681705a93cd57ad79565cfef9591122e9499897550cf324a5e5bb1bc51df0e7433cf0e91b962c90f18ac459dcc98b2431daa04aa63cb20 + languageName: node + linkType: hard + "@ampproject/remapping@npm:^2.2.0": version: 2.2.1 resolution: "@ampproject/remapping@npm:2.2.1" @@ -49,6 +56,7 @@ __metadata: version: 0.0.0-use.local resolution: "@assertive-ts/dom@workspace:packages/dom" dependencies: + "@adobe/css-tools": "npm:^4.4.3" "@assertive-ts/core": "workspace:^" "@testing-library/dom": "npm:^10.1.0" "@testing-library/react": "npm:^16.0.0"