lint: Add validation for the Swagger file.

package.json

@@ -39,6 +39,7 @@
     "nwmatcher": "1.3.6",
     "phantomjs-prebuilt": "2.1.14",
     "svgo": "0.7.2",
+    "swagger-parser": "3.4.1",
     "tslint": "5.3.2",
     "webpack-dev-server": "2.4.1",
     "xmlhttprequest": "1.5.0"

tools/check-swagger

@@ -0,0 +1,26 @@
+var SwaggerParser = require('swagger-parser');
+
+function validateSwagger(file) {
+    SwaggerParser.validate(file)
+        .then(function() {
+            // The validation passed, no need to say anything
+            return;
+        })
+        .catch(function(err) {
+            // There is something wrong. Display the validation errors
+            console.error('In', file + ':');
+            console.error(err.message);
+            process.exitCode = 1;
+        });
+}
+
+// Iterate through the changed files, passed in the arguments.
+// The two first arguments are the call to the Node interpreter and this
+// script, hence the starting point at 2.
+for(var i = 2; i < process.argv.length; i++) {
+    var file = process.argv[i];
+    // Run the validator only for YAML files inside static/swagger
+    if(file.startsWith('static/swagger')) {
+        validateSwagger(file);
+    }
+}

tools/lint

@@ -715,6 +715,7 @@ def run():
         external_linter('puppet', ['puppet', 'parser', 'validate'], ['pp'])
         external_linter('templates', ['tools/check-templates'], ['handlebars', 'html'])
         external_linter('urls', ['tools/check-urls'])
+        external_linter('swagger', ['node', 'tools/check-swagger'], ['yaml'])
 
         # gitlint disabled until we can stabilize it more
 #        if not options.no_gitlint:

version.py

@@ -1,2 +1,2 @@
 ZULIP_VERSION = "1.5.1+git"
-PROVISION_VERSION = '5.3'
+PROVISION_VERSION = '5.4'