LibJS: Start implementing Intl.Segmenter

Userland/Libraries/LibJS/Tests/builtins/Intl/Segmenter/Segmenter.@@toStringTag.js

@@ -0,0 +1,3 @@
+test("basic functionality", () => {
+    expect(Intl.Segmenter.prototype[Symbol.toStringTag]).toBe("Intl.Segmenter");
+});

Userland/Libraries/LibJS/Tests/builtins/Intl/Segmenter/Segmenter.js

@@ -0,0 +1,65 @@
+describe("errors", () => {
+    test("called without new", () => {
+        expect(() => {
+            Intl.Segmenter();
+        }).toThrowWithMessage(TypeError, "Intl.Segmenter constructor must be called with 'new'");
+    });
+
+    test("structurally invalid tag", () => {
+        expect(() => {
+            new Intl.Segmenter("root");
+        }).toThrowWithMessage(RangeError, "root is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.Segmenter("en-");
+        }).toThrowWithMessage(RangeError, "en- is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.Segmenter("Latn");
+        }).toThrowWithMessage(RangeError, "Latn is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.Segmenter("en-u-aa-U-aa");
+        }).toThrowWithMessage(RangeError, "en-u-aa-U-aa is not a structurally valid language tag");
+    });
+
+    test("options is an invalid type", () => {
+        expect(() => {
+            new Intl.Segmenter("en", null);
+        }).toThrowWithMessage(TypeError, "Options is not an object");
+    });
+
+    test("localeMatcher option is invalid", () => {
+        expect(() => {
+            new Intl.Segmenter("en", { localeMatcher: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option localeMatcher");
+    });
+
+    test("granularity option is invalid", () => {
+        expect(() => {
+            new Intl.Segmenter("en", { granularity: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option granularity");
+    });
+});
+
+describe("normal behavior", () => {
+    test("length is 0", () => {
+        expect(Intl.Segmenter).toHaveLength(0);
+    });
+
+    test("all valid localeMatcher options", () => {
+        ["lookup", "best fit"].forEach(localeMatcher => {
+            expect(() => {
+                new Intl.Segmenter("en", { localeMatcher: localeMatcher });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid granularity options", () => {
+        ["grapheme", "word", "sentence"].forEach(granularity => {
+            expect(() => {
+                new Intl.Segmenter("en", { granularity: granularity });
+            }).not.toThrow();
+        });
+    });
+});