Add tests for the Filter class.

(imported from commit ef0917bd7911c5cc6f6d20d356c156d483ba723f)

zerver/tests/frontend/node/filter.js

@@ -0,0 +1,49 @@
+var assert = require('assert');
+
+(function set_up_dependencies () {
+    global._ = require('third/underscore/underscore.js');
+
+    // An upcoming change is to put Filter in its own module, but
+    // for now it still lives in narrow.js.  (I'm waiting for a big
+    // commit from Zev to hit master first.  Once that happens,
+    // I will make js/filter.js, update the references here, and
+    // hopefully remember to delete this comment.)
+    global.narrow = require('js/narrow.js');
+    global.$ = function () {}; // for subs.js to load
+    global.subs = require('js/subs.js');
+    global.page_params = {
+        domain: 'zulip.com'
+    };
+}());
+
+var Filter = global.narrow.Filter;
+
+(function test_basics() {
+    var operators = [['stream', 'foo'], ['topic', 'bar']];
+    var filter = new Filter(operators);
+
+    assert.deepEqual(filter.operators(), operators);
+
+    var predicate = filter.predicate();
+    assert(predicate({type: 'stream', stream: 'foo', subject: 'bar'}));
+    assert(!predicate({type: 'stream', stream: 'foo', subject: 'whatever'}));
+
+    assert.deepEqual(filter.operands('stream'), ['foo']);
+
+    assert(filter.has_operator('stream'));
+    assert(!filter.has_operator('search'));
+
+    assert(filter.has_operand('stream', 'foo'));
+    assert(!filter.has_operand('stream', 'nada'));
+
+    assert(!filter.is_search());
+    assert(filter.can_apply_locally());
+
+    operators = [['stream', 'foo'], ['topic', 'bar'], ['search', 'pizza']];
+    filter = new Filter(operators);
+
+    assert(filter.is_search());
+    assert(! filter.can_apply_locally());
+}());
+
+