fix: 🐛 handle correctly basic falsy types in getType() (#47930) (#47953)

src/plugins/expressions/common/expressions/serialize_provider.test.ts

@@ -0,0 +1,48 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { getType } from './serialize_provider';
+
+describe('getType()', () => {
+  test('returns "null" string for null or undefined', () => {
+    expect(getType(null)).toBe('null');
+    expect(getType(undefined)).toBe('null');
+  });
+
+  test('returns basic type name', () => {
+    expect(getType(0)).toBe('number');
+    expect(getType(1)).toBe('number');
+    expect(getType(0.8)).toBe('number');
+    expect(getType(Infinity)).toBe('number');
+
+    expect(getType(true)).toBe('boolean');
+    expect(getType(false)).toBe('boolean');
+  });
+
+  test('returns .type property value of objects', () => {
+    expect(getType({ type: 'foo' })).toBe('foo');
+    expect(getType({ type: 'bar' })).toBe('bar');
+  });
+
+  test('throws if object has no .type property', () => {
+    expect(() => getType({})).toThrow();
+    expect(() => getType({ _type: 'foo' })).toThrow();
+    expect(() => getType({ tipe: 'foo' })).toThrow();
+  });
+});

src/plugins/expressions/common/expressions/serialize_provider.ts

@@ -20,7 +20,7 @@
 import { get, identity } from 'lodash';
 
 export function getType(node: any) {
-  if (!node) return 'null';
+  if (node == null) return 'null';
   if (typeof node === 'object') {
     if (!node.type) throw new Error('Objects must have a type property');
     return node.type;