test: add LiquidOptions#operators test

test/integration/liquid/operators-option.ts

@@ -0,0 +1,25 @@
+import { expect } from 'chai'
+import { Liquid, Operators } from '../../../src/liquid'
+
+describe('LiquidOptions#operators', function () {
+  let engine: Liquid
+
+  beforeEach(function () {
+    engine = new Liquid({
+      operators: {
+        ...Operators,
+        isFooBar: (l, r) => l === 'foo' && r === 'bar'
+      }
+    })
+  })
+
+  it('should evaluate the default operators', async function () {
+    const result = await engine.parseAndRender('{% if "foo" == "foo" %}True{% endif %}')
+    expect(result).to.equal('True')
+  })
+
+  it('should evaluate a custom operator', async function () {
+    const result = await engine.parseAndRender('{% if "foo" isFooBar "bar" %}True{% endif %}')
+    expect(result).to.equal('True')
+  })
+})