prefer-empty.md

Prefer toBeEmpty over checking innerHTML (jest-dom/prefer-empty)

💼 This rule is enabled in the ✅ recommended config.

🔧 This rule is automatically fixable by the --fix CLI option.

This rule ensures people will use toBeEmptyDOMElement() rather than checking dom nodes/properties. It is primarily aimed at consistently using jest-dom for readability.

Rule Details

This autofixable rule aims to ensure usage of .toBeEmptyDOMElement()

Examples of correct code for this rule:

expect(element.innerHTML).toBe("foo");
expect(element.innerHTML).toBe(foo);
expect(element.innerHTML).not.toBe("foo");
expect(element.innerHTML).not.toBe(foo);
expect(element.firstChild).toBe("foo");
expect(element.firstChild).not.toBe("foo");
expect(getByText("foo").innerHTML).toBe("foo");
expect(getByText("foo").innerHTML).not.toBe("foo");
expect(getByText("foo").firstChild).toBe("foo");
expect(getByText("foo").firstChild).not.toBe("foo");
expect(element.innerHTML === "").toBe(true);
expect(element.innerHTML !== "").toBe(true);
expect(element.innerHTML === "").toBe(false);
expect(element.innerHTML !== "").toBe(false);
expect(element.firstChild === null).toBe(true);
expect(element.firstChild !== null).toBe(false);
expect(element.firstChild === null).toBe(false);

Examples of incorrect code for this rule:

expect(element.innerHTML).toBe("");
expect(element.innerHTML).toBe(null);
expect(element.innerHTML).not.toBe(null);
expect(element.innerHTML).not.toBe("");
expect(element.firstChild).toBeNull();
expect(element.firstChild).toBe(null);
expect(element.firstChild).not.toBe(null);
expect(element.firstChild).not.toBeNull();
expect(getByText("foo").innerHTML).toBe("");
expect(getByText("foo").innerHTML).toStrictEqual("");
expect(getByText("foo").innerHTML).toStrictEqual(null);
expect(getByText("foo").firstChild).toBe(null);
expect(getByText("foo").firstChild).not.toBe(null);
expect(element.innerHTML === "foo").toBe(true);

When Not To Use It

Don't use this rule if you don't care if people use .toBeEmptyDOMElement().

Further Reading

https://github.com/testing-library/jest-dom#tobeemptydomelement

https://github.com/testing-library/jest-dom/blob/main/src/to-be-empty-dom-element.js

Changelog

Previously, this rule was using .toBeEmpty which has been deprecated in @testing-library/jest-dom@5.9.0.