src/hero.mjs: Add emitHeaders()

2 files changed, 30 insertions, 0 deletions

diff --git a/src/hero.mjs b/src/hero.mjs
index 6838473..a9397ef 100644
--- a/src/hero.mjs
+++ b/src/hero.mjs
@@ -279,6 +279,12 @@ export const handleRequest = async (table, reqHandle) => {
 	return await handlerFn(request);
 };
 
+export const emitHeaders = obj =>
+	Object.keys(obj)
+		.sort(u.strSortFn)
+		.map(name => `${name}: ${obj[name]}`)
+		.join("\r\n");
+
 export const makeRequestListener = table => async (req, res) => {
 	const { status, headers, body } = await handleRequest(table, req);
 	res.writeHead(status, headers);
diff --git a/tests/js/hero.mjs b/tests/js/hero.mjs
index 171e01f..d57152f 100644
--- a/tests/js/hero.mjs
+++ b/tests/js/hero.mjs
@@ -31,6 +31,7 @@ import {
 	handle404,
 	make404Handler,
 	handleRequest,
+	emitHeaders,
 	makeRequestListener,
 	actionsFn,
 	lineHandlerFn,
@@ -1142,6 +1143,28 @@ const test_handleRequest = async t => {
 	});
 };
 
+const test_emitHeaders = async t => {
+	t.start("emitHeaders()");
+
+	await t.test("empty values", () => {
+		assert.equal(emitHeaders({}), "");
+		assert.equal(emitHeaders({ "": "" }), ": ");
+		assert.equal(emitHeaders({ " ": " " }), " :  ");
+		assert.equal(emitHeaders({ "_": "_" }), "_: _");
+	});
+
+	await t.test("newlines are forwarded", () => {
+		assert.equal(emitHeaders({"\na\n": "\nb\n"}), "\na\n: \nb\n");
+	});
+
+	await t.test("keys are always sorted", () => {
+		assert.equal(
+			emitHeaders({ "a": "one", "Z": "two" }),
+			"a: one\r\nZ: two",
+		);
+	});
+};
+
 const test_makeRequestListener = async t => {
 	t.start("makeRequestListener()");
 
@@ -1834,6 +1857,7 @@ await runner.runTests([
 	test_extractQueryParams,
 	test_make404Handler,
 	test_handleRequest,
+	test_emitHeaders,
 	test_makeRequestListener,
 	test_actionsFn,
 	test_lineHandlerFn,