LibJS: Implement Intl.PluralRules.prototype.selectRange

Userland/Libraries/LibJS/Tests/builtins/Intl/PluralRules/PluralRules.prototype.selectRange.js

@@ -0,0 +1,73 @@
+describe("errors", () => {
+    test("called on non-PluralRules object", () => {
+        expect(() => {
+            Intl.PluralRules.prototype.selectRange();
+        }).toThrowWithMessage(TypeError, "Not an object of type Intl.PluralRules");
+    });
+
+    test("called without enough values", () => {
+        expect(() => {
+            new Intl.PluralRules().selectRange();
+        }).toThrowWithMessage(TypeError, "start is undefined");
+
+        expect(() => {
+            new Intl.PluralRules().selectRange(1);
+        }).toThrowWithMessage(TypeError, "end is undefined");
+    });
+
+    test("called with values that cannot be converted to numbers", () => {
+        expect(() => {
+            new Intl.PluralRules().selectRange(Symbol.hasInstance, 1);
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+
+        expect(() => {
+            new Intl.PluralRules().selectRange(1, Symbol.hasInstance);
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+    });
+
+    test("called with invalid numbers", () => {
+        expect(() => {
+            new Intl.PluralRules().selectRange(NaN, 1);
+        }).toThrowWithMessage(RangeError, "start must not be NaN");
+
+        expect(() => {
+            new Intl.PluralRules().selectRange(1, NaN);
+        }).toThrowWithMessage(RangeError, "end must not be NaN");
+
+        expect(() => {
+            new Intl.PluralRules().selectRange(1, 0);
+        }).toThrowWithMessage(RangeError, "Range start 1 is greater than range end 0");
+    });
+});
+
+describe("correct behavior", () => {
+    test("basic functionality", () => {
+        const en = new Intl.PluralRules("en");
+        expect(en.selectRange(1, 2)).toBe("other"); // one + other = other
+        expect(en.selectRange(0, 1)).toBe("other"); // other + one = other
+        expect(en.selectRange(2, 3)).toBe("other"); // other + other = other
+
+        const pl = new Intl.PluralRules("pl");
+        expect(pl.selectRange(1, 2)).toBe("few"); // one + few = few
+        expect(pl.selectRange(1, 5)).toBe("many"); // one + many = many
+        expect(pl.selectRange(1, 3.14)).toBe("other"); // one + other = other
+        expect(pl.selectRange(2, 2)).toBe("few"); // few + few = few
+        expect(pl.selectRange(2, 5)).toBe("many"); // few + many = many
+        expect(pl.selectRange(2, 3.14)).toBe("other"); // few + other = other
+        expect(pl.selectRange(0, 1)).toBe("one"); // many + one = one
+        expect(pl.selectRange(0, 2)).toBe("few"); // many + few = few
+        expect(pl.selectRange(0, 5)).toBe("many"); // many + many = many
+        expect(pl.selectRange(0, 3.14)).toBe("other"); // many + other = other
+        expect(pl.selectRange(0.14, 1)).toBe("one"); // other + one = one
+        expect(pl.selectRange(0.14, 2)).toBe("few"); // other + few = few
+        expect(pl.selectRange(0.14, 5)).toBe("many"); // other + many = many
+        expect(pl.selectRange(0.14, 3.14)).toBe("other"); // other + other = other
+    });
+
+    test("default to end of range", () => {
+        // "so" specifies "one" to be the integer 1, but does not specify any ranges.
+        const so = new Intl.PluralRules("so");
+        expect(so.selectRange(0, 1)).toBe("one");
+        expect(so.selectRange(1, 2)).toBe("other");
+    });
+});