code: function getCallerLocation() {
      const error = new Error();
      if (error.stack) {
          const lines = error.stack.split("\n");
          for (let i = 2; i < lines.length; i++) {
              if (i > 0 && lines[i] === "    at <anonymous>") {
                  const paren = lines[i - 1].indexOf("(");
                  if (paren >= 0) {
                      return lines[i - 1].slice(paren + 1, lines[i - 1].length - 1);
                  }
                  else {
                      return "";
                  }
              }
              else if (!lines[i].startsWith("    at CanaryTest.") &&
                  !lines[i].startsWith("    at new CanaryTest")) {
                  const paren = lines[i].indexOf("(");
                  if (paren >= 0) {
                      return lines[i].slice(paren + 1, lines[i].length - 1);
                  }
                  else {
                      return lines[i].slice(7, lines[i].length);
                  }
              }
          }
      }
      return "";
  }
docs: Helper function to get the path to the file where a test was defined.