Add test that shows an infinite loop with an invalid mustache template

tests/template/crow_extra_mustache_tests.json

@@ -0,0 +1,15 @@
+{
+  "overview": "Check Crow's behaviour when given invalid mustache templates",
+  "tests": [
+    {
+      "name": "Missing end-tags",
+      "desc": "Missing end-tags should fail to render ... and not enter infinite loops or other undefined behaviour",
+      "data": {
+        "boolean": true
+      },
+      "template": "\"{{#boolean}}{{^boolean}}\"",
+      "expected": "COMPILE EXCEPTION: crow::mustache error: open tag has no matching end tag {{# {{/ pair: boolean"
+    }
+  ],
+  "__ATTN__": "This file was hand-written"
+}

tests/template/mustachetest.cpp

@@ -18,17 +18,23 @@ string read_all(const string& filename)
 
 int main()
 {
-    auto data = json::load(read_all("data"));
-    auto templ = compile(read_all("template"));
-    auto partials = json::load(read_all("partials"));
-    set_loader([&](std::string name) -> std::string {
-        if (partials.count(name))
-        {
-            return partials[name].s();
-        }
-        return "";
-    });
-    context ctx(data);
-    cout << templ.render_string(ctx);
+    try {
+        auto data = json::load(read_all("data"));
+        auto templ = compile(read_all("template"));
+        auto partials = json::load(read_all("partials"));
+        set_loader([&](std::string name) -> std::string {
+            if (partials.count(name))
+            {
+                return partials[name].s();
+            }
+            return "";
+        });
+        context ctx(data);
+        cout << templ.render_string(ctx);
+    }
+    // catch and return compile errors as text, for the python test to compare
+    catch (invalid_template_exception & err) {
+        cout << "COMPILE EXCEPTION: " << err.what();
+    }
     return 0;
 }

tests/template/test.py

@@ -30,7 +30,7 @@
             print('Data: ', json.dumps(test["data"]))
             print('Template: ', test["template"])
             print('Expected:', repr(test["expected"]))
-            print('Actual:', repr(ret))
+            print('Actual:  ', repr(ret))
         assert ret == test["expected"]
 
         os.unlink('data')