feat(viewer): mode pretty print avec coloration syntaxique et numeros de ligne pour fichiers texte (#89)

tests/frontend/pretty.test.mjs

@@ -0,0 +1,71 @@
+/**
+ * Frontend tests for Pretty print helpers (#89).
+ * detectPrettyLang / buildPrettyHtml are pure functions extracted from
+ * frontend/js/viewer.js; they are evaluated in a sandbox to avoid importing
+ * the full viewer module chain (browser-only dependencies).
+ */
+
+import { strict as assert } from "node:assert";
+import { readFileSync } from "node:fs";
+import vm from "node:vm";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const src = readFileSync(path.join(__dirname, "..", "..", "frontend", "js", "viewer.js"), "utf8");
+
+function extractFn(name) {
+  const start = src.indexOf(`function ${name}(`);
+  assert.ok(start !== -1, `function ${name} not found in viewer.js`);
+  let depth = 0;
+  let i = src.indexOf("{", start);
+  const begin = i;
+  for (; i < src.length; i++) {
+    if (src[i] === "{") depth++;
+    else if (src[i] === "}") {
+      depth--;
+      if (depth === 0) break;
+    }
+  }
+  return src.slice(start, i + 1);
+}
+
+function escapeHtml(s) {
+  return String(s)
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;")
+    .replace(/"/g, "&quot;");
+}
+
+const sandbox = { escapeHtml };
+vm.createContext(sandbox);
+vm.runInContext(`${extractFn("detectPrettyLang")}\n${extractFn("buildPrettyHtml")}\nglobalThis.detectPrettyLang = detectPrettyLang; globalThis.buildPrettyHtml = buildPrettyHtml;`, sandbox);
+const { detectPrettyLang, buildPrettyHtml } = sandbox;
+
+console.log("Testing detectPrettyLang...");
+assert.equal(detectPrettyLang({ is_json: true }), "json");
+assert.equal(detectPrettyLang({ extension: ".json" }), "json");
+assert.equal(detectPrettyLang({ extension: ".py", html: '<pre><code class="language-python">x</code></pre>' }), "python");
+assert.equal(detectPrettyLang({ extension: ".sh", html: '<pre><code class="language-bash">x</code></pre>' }), "bash");
+assert.equal(detectPrettyLang({ extension: ".txt", html: "<pre><code>x</code></pre>" }), "plaintext");
+
+console.log("Testing buildPrettyHtml (json reformat)...");
+const jsonOut = buildPrettyHtml({ is_json: true }, '{"a":1,"b":[2,3]}');
+assert.ok(jsonOut.includes("pretty-view"), "wrapper class present");
+assert.ok(jsonOut.includes("pp-gutter"), "gutter present");
+assert.ok(jsonOut.includes('class="language-json"'), "language class present");
+// 4 formatted lines: {, "a": 1, "b": [...], } -> gutter must show 4 numbers at least
+assert.ok(/<span>4<\/span>/.test(jsonOut), "line numbers computed on formatted text");
+assert.ok(jsonOut.includes("&quot;a&quot;"), "HTML-escaped quotes");
+
+console.log("Testing buildPrettyHtml (invalid json falls back to raw)...");
+const bad = buildPrettyHtml({ is_json: true }, "{not valid json}");
+assert.ok(bad.includes("{not valid json}"), "raw content displayed when JSON invalid");
+
+console.log("Testing buildPrettyHtml (xss escaped)...");
+const xss = buildPrettyHtml({ extension: ".py", html: "" }, 'print("<script>alert(1)</script>")');
+assert.ok(!xss.includes("<script>"), "no raw script tag injected");
+assert.ok(xss.includes("&lt;script&gt;"), "script tag escaped");
+
+console.log("✅ All pretty-print tests passed successfully!");