diff --git a/x-pack/test/api_integration/apis/index.js b/x-pack/test/api_integration/apis/index.js
index ed0e6488320d4..fd700b41df563 100644
--- a/x-pack/test/api_integration/apis/index.js
+++ b/x-pack/test/api_integration/apis/index.js
@@ -28,5 +28,6 @@ export default function ({ loadTestFile }) {
     loadTestFile(require.resolve('./short_urls'));
     loadTestFile(require.resolve('./lens'));
     loadTestFile(require.resolve('./endpoint'));
+    loadTestFile(require.resolve('./ml'));
   });
 }
diff --git a/x-pack/test/api_integration/apis/ml/bucket_span_estimator.ts b/x-pack/test/api_integration/apis/ml/bucket_span_estimator.ts
new file mode 100644
index 0000000000000..b5e5168621584
--- /dev/null
+++ b/x-pack/test/api_integration/apis/ml/bucket_span_estimator.ts
@@ -0,0 +1,90 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import expect from '@kbn/expect';
+
+import { FtrProviderContext } from '../../ftr_provider_context';
+
+const COMMON_HEADERS = {
+  'kbn-xsrf': 'some-xsrf-token',
+};
+
+const testDataList = [
+  {
+    testTitleSuffix: 'with 1 field, 1 agg, no split',
+    requestBody: {
+      aggTypes: ['avg'],
+      duration: { start: 1560297859000, end: 1562975136000 },
+      fields: ['taxless_total_price'],
+      index: 'ecommerce',
+      query: { bool: { must: [{ match_all: {} }] } },
+      timeField: 'order_date',
+    },
+    expected: {
+      responseCode: 200,
+      responseBody: { name: '15m', ms: 900000 },
+    },
+  },
+  {
+    testTitleSuffix: 'with 2 fields, 2 aggs, no split',
+    requestBody: {
+      aggTypes: ['avg', 'sum'],
+      duration: { start: 1560297859000, end: 1562975136000 },
+      fields: ['products.base_price', 'products.base_unit_price'],
+      index: 'ecommerce',
+      query: { bool: { must: [{ match_all: {} }] } },
+      timeField: 'order_date',
+    },
+    expected: {
+      responseCode: 200,
+      responseBody: { name: '30m', ms: 1800000 },
+    },
+  },
+  {
+    testTitleSuffix: 'with 1 field, 1 agg, 1 split with cardinality 46',
+    requestBody: {
+      aggTypes: ['avg'],
+      duration: { start: 1560297859000, end: 1562975136000 },
+      fields: ['taxless_total_price'],
+      index: 'ecommerce',
+      query: { bool: { must: [{ match_all: {} }] } },
+      splitField: 'customer_first_name.keyword',
+      timeField: 'order_date',
+    },
+    expected: {
+      responseCode: 200,
+      responseBody: { name: '3h', ms: 10800000 },
+    },
+  },
+];
+
+// eslint-disable-next-line import/no-default-export
+export default ({ getService }: FtrProviderContext) => {
+  const esArchiver = getService('esArchiver');
+  const supertest = getService('supertest');
+
+  describe('bucket span estimator', () => {
+    before(async () => {
+      await esArchiver.load('ml/ecommerce');
+    });
+
+    after(async () => {
+      await esArchiver.unload('ml/ecommerce');
+    });
+
+    for (const testData of testDataList) {
+      it(`estimates the bucket span ${testData.testTitleSuffix}`, async () => {
+        const { body } = await supertest
+          .post('/api/ml/validate/estimate_bucket_span')
+          .set(COMMON_HEADERS)
+          .send(testData.requestBody)
+          .expect(testData.expected.responseCode);
+
+        expect(body).to.eql(testData.expected.responseBody);
+      });
+    }
+  });
+};
diff --git a/x-pack/test/api_integration/apis/ml/index.ts b/x-pack/test/api_integration/apis/ml/index.ts
new file mode 100644
index 0000000000000..2e0521e2b8273
--- /dev/null
+++ b/x-pack/test/api_integration/apis/ml/index.ts
@@ -0,0 +1,15 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { FtrProviderContext } from '../../ftr_provider_context';
+
+export default function({ loadTestFile }: FtrProviderContext) {
+  describe('Machine Learning', function() {
+    this.tags(['mlqa']);
+
+    loadTestFile(require.resolve('./bucket_span_estimator'));
+  });
+}