test: add unit tests for error handling, import resolution, and source tracking

Author: YieldRay

src/error.test.ts

@@ -0,0 +1,31 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import { ModuleTSXError, warn } from "./error.ts";
+
+describe("ModuleTSXError", () => {
+  it("is an instance of Error", () => {
+    const err = new ModuleTSXError("oops");
+    assert.ok(err instanceof Error);
+    assert.ok(err instanceof ModuleTSXError);
+  });
+
+  it("has name ModuleTSXError", () => {
+    assert.equal(new ModuleTSXError("x").name, "ModuleTSXError");
+  });
+
+  it("preserves message", () => {
+    assert.equal(new ModuleTSXError("hello").message, "hello");
+  });
+
+  it("supports cause via ErrorOptions", () => {
+    const cause = new Error("root");
+    const err = new ModuleTSXError("wrapped", { cause });
+    assert.equal((err as any).cause, cause);
+  });
+});
+
+describe("warn", () => {
+  it("does not throw", () => {
+    assert.doesNotThrow(() => warn("test message", 1, 2));
+  });
+});

src/importmap.test.ts

@@ -0,0 +1,61 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import { resolveFromImportMap } from "./importmap.ts";
+import type { ImportMapData } from "./importmap.ts";
+
+// parseImportMaps() requires a DOM — tested via the browser demo only
+
+describe("resolveFromImportMap", () => {
+  it("resolves from global imports", () => {
+    const map: ImportMapData = { imports: { react: "https://esm.sh/react" } };
+    assert.equal(resolveFromImportMap("react", map), "https://esm.sh/react");
+  });
+
+  it("returns undefined for unknown specifier", () => {
+    const map: ImportMapData = { imports: { react: "https://esm.sh/react" } };
+    assert.equal(resolveFromImportMap("vue", map), undefined);
+  });
+
+  it("resolves from matching scope over global imports", () => {
+    const map: ImportMapData = {
+      imports: { react: "https://esm.sh/react" },
+      scopes: {
+        "https://example.com/app/": { react: "https://esm.sh/react@18" },
+      },
+    };
+    assert.equal(
+      resolveFromImportMap("react", map, "https://example.com/app/main.js"),
+      "https://esm.sh/react@18",
+    );
+  });
+
+  it("falls back to global imports when no scope matches", () => {
+    const map: ImportMapData = {
+      imports: { react: "https://esm.sh/react" },
+      scopes: {
+        "https://example.com/other/": { react: "https://esm.sh/react@17" },
+      },
+    };
+    assert.equal(
+      resolveFromImportMap("react", map, "https://example.com/app/main.js"),
+      "https://esm.sh/react",
+    );
+  });
+
+  it("prefers more specific scope", () => {
+    const map: ImportMapData = {
+      scopes: {
+        "https://example.com/": { react: "https://esm.sh/react@17" },
+        "https://example.com/app/": { react: "https://esm.sh/react@18" },
+      },
+    };
+    assert.equal(
+      resolveFromImportMap("react", map, "https://example.com/app/main.js"),
+      "https://esm.sh/react@18",
+    );
+  });
+
+  it("returns undefined when imports and scopes are empty", () => {
+    assert.equal(resolveFromImportMap("react", {}), undefined);
+  });
+});