35 lines
802 B
JavaScript
35 lines
802 B
JavaScript
test("extending function", () => {
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class A extends function () {
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this.foo = 10;
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} {}
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expect(new A().foo).toBe(10);
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});
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test("extending null", () => {
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class A extends null {}
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expect(Object.getPrototypeOf(A.prototype)).toBeNull();
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expect(() => {
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new A();
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}).toThrowWithMessage(ReferenceError, "|this| has not been initialized");
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});
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test("extending String", () => {
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class MyString extends String {}
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const ms = new MyString("abc");
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expect(ms).toBeInstanceOf(MyString);
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expect(ms).toBeInstanceOf(String);
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expect(ms.charAt(1)).toBe("b");
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class MyString2 extends MyString {
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charAt(i) {
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return `#${super.charAt(i)}`;
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}
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}
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const ms2 = new MyString2("abc");
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expect(ms2.charAt(1)).toBe("#b");
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});
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