feat(shaka-lab-node): Add support for Chromecast redirect mode (#52)

Chromecast WebDriver Server v2 adds support for a redirect mode, where
it does not rely on an iframe. This has many advantages for Shaka Player
testing.

This adds support for this mode in shaka-lab-node, and enables it by
default in the Shaka lab.

To accomplish this for Chromecast, we add general support for optional
parameters with default values in the node template.

shaka-lab-node/node-templates.md

@@ -89,7 +89,9 @@ xboxone:
 Here, the template has parameters `hostname`, `username`, `password`, and
 `msbuild`.  The `?` in `?msbuild` indicates that it is an optional parameter.
 The property definitions passed to Selenium then reference those as variables,
-such as `$hostname`, `$username`, etc.
+such as `$hostname`, `$username`, etc.  An optional parameter can also have a
+default value.  For example, to have an optional parameter named `redirect`
+that defaults to `true`, you would specify `?redirect=true`.
 
 
 ## Built-in Variables

shaka-lab-node/node-templates.yaml

@@ -60,13 +60,16 @@ chromecast:
     - version
     - ?receiver-app-id  # optional
     - ?idle-timeout-seconds  # optional
+    - ?connection-timeout-seconds  # optional
+    - ?redirect=true  # optional, default true
   defs:
     genericwebdriver.browser.name: chromecast
     genericwebdriver.backend.exe: node_modules/.bin/chromecast-webdriver-server$cmd
     genericwebdriver.backend.params.hostname: $hostname
     genericwebdriver.backend.params.receiver-app-id: $receiver-app-id
     genericwebdriver.backend.params.idle-timeout-seconds: $idle-timeout-seconds
     genericwebdriver.backend.params.connection-timeout-seconds: $connection-timeout-seconds
+    genericwebdriver.backend.params.redirect: $redirect
   capabilities:
     browserName: chromecast
     version: $version

shaka-lab-node/package.json

@@ -1,7 +1,7 @@
 {
   "private": true,
   "dependencies": {
-    "chromecast-webdriver-server": "^1",
+    "chromecast-webdriver-server": "^2",
     "chromeos-webdriver-server": "^1",
     "generic-webdriver-server": "^1",
     "js-yaml": "^4",

shaka-lab-node/start-nodes.js

@@ -119,18 +119,32 @@ function requiredParam(nodeConfig, templateName, paramName) {
   return nodeConfig.params[paramName];
 }
 
+/**
+ * @param {string} paramSpec
+ * @return {[string, string]}
+ */
+function parseOptionalParamSpec(paramSpec) {
+  // remove leading '?', split by optional '='
+  const paramSpecParts = paramSpec.substr(1).split('=');
+
+  const paramName = paramSpecParts.shift();
+  const defaultValue = paramSpecParts.length ? paramSpecParts.join('=') : '';
+  return [paramName, defaultValue];
+}
+
 /**
  * Access an optional param from a node config, or return a blank default.
  *
  * @param {Object} nodeConfig
  * @param {string} paramName
+ * @param {string} defaultValue
  * @return {string}
  */
-function optionalParam(nodeConfig, paramName) {
+function optionalParam(nodeConfig, paramName, defaultValue) {
   if (nodeConfig.params && paramName in nodeConfig.params) {
     return nodeConfig.params[paramName];
   }
-  return '';
+  return defaultValue;
 }
 
 /**
@@ -218,8 +232,11 @@ function main() {
         const optional = paramName.startsWith('?');
 
         if (optional) {
-          paramName = paramName.substr(1);  // remove leading '?'
-          params[paramName] = optionalParam(nodeConfig, paramName);
+          let defaultValue;
+          [paramName, defaultValue] = parseOptionalParamSpec(paramName);
+
+          params[paramName] = optionalParam(
+              nodeConfig, paramName, defaultValue);
         } else {
           params[paramName] = requiredParam(
               nodeConfig, templateName, paramName);
@@ -298,6 +315,7 @@ function main() {
   for (const args of nodeCommands) {
     const command = args.shift();
 
+    console.log('Spawning child process:', args);
     const child = child_process.spawn(command, args, spawnOptions);
 
     child.once('error', (event) => {