LibJS: Implement Number.prototype.toExponential

Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.toExponential.js

@@ -0,0 +1,90 @@
+describe("errors", () => {
+    test("must be called with numeric |this|", () => {
+        [true, [], {}, Symbol("foo"), "bar", 1n].forEach(value => {
+            expect(() => {
+                Number.prototype.toExponential.call(value);
+            }).toThrowWithMessage(TypeError, "Not an object of type Number");
+        });
+    });
+
+    test("fraction digits must be coercible to a number", () => {
+        expect(() => {
+            (0).toExponential(Symbol("foo"));
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+
+        expect(() => {
+            (0).toExponential(1n);
+        }).toThrowWithMessage(TypeError, "Cannot convert BigInt to number");
+    });
+
+    test("out of range fraction digits", () => {
+        [-Infinity, -1, 101, Infinity].forEach(value => {
+            expect(() => {
+                (0).toExponential(value);
+            }).toThrowWithMessage(
+                RangeError,
+                "Fraction Digits must be an integer no less than 0, and no greater than 100"
+            );
+        });
+    });
+});
+
+describe("correct behavior", () => {
+    test("special values", () => {
+        [
+            [Infinity, 6, "Infinity"],
+            [-Infinity, 7, "-Infinity"],
+            [NaN, 8, "NaN"],
+            [0, 0, "0e+0"],
+            [0, 1, "0.0e+0"],
+            [0, 3, "0.000e+0"],
+        ].forEach(test => {
+            expect(test[0].toExponential(test[1])).toBe(test[2]);
+        });
+    });
+
+    test("zero exponent", () => {
+        [
+            [1, 0, "1e+0"],
+            [5, 1, "5.0e+0"],
+            [9, 3, "9.000e+0"],
+        ].forEach(test => {
+            expect(test[0].toExponential(test[1])).toBe(test[2]);
+        });
+    });
+
+    test("positive exponent", () => {
+        [
+            [12, 0, "1e+1"],
+            [345, 1, "3.5e+2"],
+            [6789, 3, "6.789e+3"],
+        ].forEach(test => {
+            expect(test[0].toExponential(test[1])).toBe(test[2]);
+        });
+    });
+
+    test("negative exponent", () => {
+        [
+            [0.12, 0, "1e-1"],
+            [0.0345, 1, "3.5e-2"],
+            [0.006789, 3, "6.789e-3"],
+        ].forEach(test => {
+            expect(test[0].toExponential(test[1])).toBe(test[2]);
+        });
+    });
+
+    test("undefined precision", () => {
+        [
+            [123.456, "1.23456e+2"],
+            [13, "1.3e+1"],
+            [100, "1e+2"],
+            [345, "3.45e+2"],
+            [6789, "6.789e+3"],
+            [0.13, "1.3e-1"],
+            [0.0345, "3.45e-2"],
+            [0.006789, "6.789e-3"],
+        ].forEach(test => {
+            expect(test[0].toExponential()).toBe(test[1]);
+        });
+    });
+});