chore: Launch script for demo-app (#2247)

Usage: `yarn demo-app` from root folder.

closes #2236

Author: trimox

docs/developer.md

@@ -11,12 +11,11 @@
 4. Clone your fork to your machine with `git clone`.
 5. From the root of the project, run `yarn` to install the dependencies.
 
-## <a name="setupdemos"></a> Install demo dependencies
-Change path to `/demos`, run `yarn` to install dependencies.
-
 ## <a name="demo-server"></a> Run demo application
-Change path to `/demos`, run `yarn start`.
-
+From the root of the project,
+```
+yarn demo-app
+```
 After your development server is running, open a browser to url: http://localhost:4200
 
 ## <a name="lint"></a> Linting

package.json

@@ -19,6 +19,7 @@
     "bazel:buildifier": "find . -type f \\( -name \"*.bzl\" -or -name WORKSPACE -or -name BUILD -or -name BUILD.bazel \\) ! -path \"*/node_modules/*\" | xargs buildifier -v --warnings=attr-cfg,attr-license,attr-non-empty,attr-output-default,attr-single-file,constant-glob,ctx-args,depset-iteration,depset-union,dict-concatenation,duplicated-name,filetype,git-repository,http-archive,integer-division,load,load-on-top,native-build,native-package,output-group,package-name,package-on-top,redefined-variable,repository-name,same-origin-load,string-iteration,unused-variable,unsorted-dict-items,out-of-order-load",
     "bazel:format-lint": "yarn -s bazel:buildifier --lint=warn --mode=check",
     "changelog": "conventional-changelog -p angular -i CHANGELOG.md -s",
+    "demo-app": "node ./scripts/run-demo-app.js",
     "lint": "yarn -s tslint && yarn -s bazel:format-lint",
     "tslint": "tslint -c tslint.json --project ./tsconfig.json",
     "lint:css": "stylelint \"packages/material-components-web/**/*.scss\"",

scripts/run-demo-app.js

@@ -0,0 +1,33 @@
+#!/usr/bin/env node
+
+/**
+ * Script that runs the demo-app.
+ */
+
+const {execSync} = require('child_process');
+const {set, cd} = require('shelljs');
+const {join} = require('path');
+
+// ShellJS should throw if any command fails.
+set('-e');
+
+/** Path to the demo directory. */
+const projectDirPath = join(__dirname, '../demos');
+
+// Go to demos directory.
+cd(projectDirPath);
+
+// Check if dependencies are installed, run demo-app.
+exec('yarn && yarn start');
+
+function exec(command, captureStdout) {
+  const stdout = execSync(command, {
+    cwd: projectDirPath,
+    stdio: ['inherit', captureStdout ? 'pipe' : 'inherit', 'inherit'],
+  });
+
+  if (captureStdout) {
+    process.stdout.write(stdout);
+    return stdout.toString().trim();
+  }
+}