Instrumentation Design

function fn(x) {
  var y;
  switch(x) {
    case 1: y = "one"; break;
    case 2:
    case 3: y = "two or three"; break;
    default: y = "unknown";
  }
  if (y === "one") {
    return y;
  }
  return "not one";
}
fn(1)

//Create the coverage object (var name is configurable)
if (!jscover) var jscover = {
//beF=boolean expression function to record true/false path
// result - boolean result
// u - URI path
// n - count (i.e. n'th boolean expression)
    beF: function (result, u, n) {
            if (result)this[u].be['' + n][0]++;else this[u].be['' + n][1]++;
            return result
         }
}
/*
s = statement. Property is the statement number, integer id the hits
sM = statement map. Property is the statement number, and record the code position
b = branch with varying number of paths (i.e switch cases)
bM = branch map data
be = boolean expression (NB: "br": "true" if this is used for determining a branch path)
beM = boolean expression map data
f = records function hits
fM = function map data
*/
if (!jscover['test.js']) {
    jscover['test.js'] = {
        "s": {"1": 0, "2": 0, "3": 0, "4": 0
            , "5": 0, "6": 0, "7": 0, "8": 0, "9": 0},
        "sM": {"1": {"pos": {"line": 1, "col": 0, "len": 212}},
            "2": {"pos": {"line": 2, "col": 2, "len": 6}},
            "3": {"pos": {"line": 4, "col": 12, "len": 10}},
            "4": {"pos": {"line": 6, "col": 12, "len": 19}},
            "5": {"pos": {"line": 7, "col": 13, "len": 14}},
            "6": {"pos": {"line": 9, "col": 2, "len": 35}},
            "7": {"pos": {"line": 10, "col": 4, "len": 9}},
            "8": {"pos": {"line": 12, "col": 2, "len": 17}},
            "9": {"pos": {"line": 14, "col": 0, "len": 5}}},
        "b": {"1": [0, 0, 0, 0]},
        "bM": {"1": [
            {"pos": {"line": 4, "col": 4, "len": 25}},
            {"pos": {"line": 5, "col": 4, "len": 7}},
            {"pos": {"line": 6, "col": 4, "len": 34}},
            {"pos": {"line": 7, "col": 4, "len": 8}}
        ]
        },
        "be": {"1": [0, 0]},
        "beM": {"1": {"pos": {"line": 9, "col": 6, "len": 10}, "br": "true"}},
        "f": {"1": 0},
        "fM": {"1": {"pos": {"line": 1, "col": 0, "len": 212}}}
    }
}
jscover["test.js"].s["1"]++;
function fn(x) {
    jscover["test.js"].f["1"]++;
    jscover["test.js"].s["2"]++;
    var y;
    switch (x) {
        case 1:
            jscover["test.js"].b["1"][0]++;
            jscover["test.js"].s["3"]++;
            y = "one";
            jscover["test.js"].s["4"]++;
            break;
        case 2:
            jscover["test.js"].b["1"][1]++;
        case 3:
            jscover["test.js"].b["1"][2]++;
            jscover["test.js"].s["5"]++;
            y = "two or three";
            jscover["test.js"].s["6"]++;
            break;
        default:
            jscover["test.js"].b["1"][3]++;
            jscover["test.js"].s["7"]++;
            y = "unknown"
    }
    jscover["test.js"].s["8"]++;
    if (jscover.beF(y === "one", "test.js", 1)) {
        jscover["test.js"].s["9"]++;
        return y
    }
    jscover["test.js"].s["10"]++;
    return"not one"
}
jscover["test.js"].s["11"]++;
fn(1)