fix(template-function-json): escape control characters in json.escape (#607)

plugins/template-function-json/package.json

@@ -8,7 +8,8 @@
   "types": "src/index.ts",
   "scripts": {
     "build": "yaakcli build",
-    "dev": "yaakcli dev"
+    "dev": "yaakcli dev",
+    "test": "vp test --run tests"
   },
   "dependencies": {
     "jsonpath-plus": "^10.3.0"

plugins/template-function-json/src/index.ts

@@ -85,7 +85,11 @@ export const plugin: PluginDefinition = {
       ],
       async onRender(_ctx: Context, args: CallTemplateFunctionArgs): Promise<string | null> {
         const input = String(args.values.input ?? "");
-        return input.replace(/\\/g, "\\\\").replace(/"/g, '\\"');
+        // JSON.stringify produces a spec-correct string literal: it escapes
+        // the backslash and quote this used to handle, and also the control
+        // characters it did not. Slicing off the surrounding quotes leaves
+        // the escaped inner text this function is meant to emit.
+        return JSON.stringify(input).slice(1, -1);
       },
     },
     {

plugins/template-function-json/tests/escape.test.ts

@@ -0,0 +1,50 @@
+import type { Context } from "@yaakapp/api";
+import { describe, expect, it } from "vite-plus/test";
+import { plugin } from "../src";
+
+const LF = String.fromCharCode(10);
+const TAB = String.fromCharCode(9);
+const CR = String.fromCharCode(13);
+
+describe("json.escape", () => {
+  const escapeFunction = plugin.templateFunctions?.find((f) => f.name === "json.escape");
+
+  const escape = async (input: string) =>
+    await escapeFunction!.onRender({} as Context, { values: { input } } as never);
+
+  // The point of the function is that the result can be dropped between two
+  // quotes in a JSON document, so that is what these assert.
+  const embeds = (escaped: string | null) => {
+    JSON.parse(`{"k":"${escaped}"}`);
+    return JSON.parse(`{"k":"${escaped}"}`).k;
+  };
+
+  it("should exist", () => {
+    expect(escapeFunction).toBeTruthy();
+  });
+
+  it("escapes a quote", async () => {
+    const input = `say "hi"`;
+    expect(embeds(await escape(input))).toBe(input);
+  });
+
+  it("escapes a backslash", async () => {
+    const input = `a${String.fromCharCode(92)}b`;
+    expect(embeds(await escape(input))).toBe(input);
+  });
+
+  it("escapes a newline", async () => {
+    const input = `line1${LF}line2`;
+    expect(embeds(await escape(input))).toBe(input);
+  });
+
+  it("escapes a tab and a carriage return", async () => {
+    const input = `a${TAB}b${CR}c`;
+    expect(embeds(await escape(input))).toBe(input);
+  });
+
+  it("round-trips a pretty-printed JSON document", async () => {
+    const input = JSON.stringify({ name: `he said "hi"`, items: [1, 2] }, null, 2);
+    expect(embeds(await escape(input))).toBe(input);
+  });
+});