Refactor vtc: prep for different json sources

src/vtc/vmod_frozen.vtc

@@ -66,15 +66,19 @@ varnish v1 -vcl+backend {
     }
     sub vcl_synth {
 	set resp.http.fail = p_test.parse(req.http.not);
-	set resp.http.parse =
-	  p_test.parse({"{ a: 1, b: "hi there", c: true, d: false, "} +
-	{" e : null, f: [ 1, -2, 3], g: { "1": [], h: [ 7 ] } } "});
+	if (req.url == "/static") {
+		set resp.http.parse =
+		    p_test.parse(
+			{"{ a: 1, b: "hi there", c: true, d: false, "} +
+			{" e : null, f: [ 1, -2, 3], g: { "1": [], h"} +
+			{": [ 7 ] } } "});
+	}
 	call extract;
     }
 } -start
 
 client c1 {
-	txreq
+	txreq -url "/static"
 	rxresp
 	expect resp.status == 200
 	expect resp.http.fail == false