diff --git a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_pattern.test.js b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_pattern.test.ts
similarity index 58%
rename from src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_pattern.test.js
rename to src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_pattern.test.ts
index a6b0470abca4c..d89a4a35e6e9f 100644
--- a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_pattern.test.js
+++ b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_pattern.test.ts
@@ -17,18 +17,23 @@
  * under the License.
  */
 
-import _ from 'lodash';
-import mockLogstashFields from '../../../../../../fixtures/logstash_fields';
-import { stubbedSavedObjectIndexPattern } from '../../../../../../fixtures/stubbed_saved_object_index_pattern';
+import { defaults, pluck, last, get } from 'lodash';
 import { IndexedArray } from 'ui/indexed_array';
+import { IndexPattern } from './index_pattern';
+
+// @ts-ignore
 import { DuplicateField } from 'ui/errors';
+// @ts-ignore
+import mockLogStashFields from '../../../../../../fixtures/logstash_fields';
+// @ts-ignore
 
-import { IndexPattern } from './index_pattern';
+import { stubbedSavedObjectIndexPattern } from '../../../../../../fixtures/stubbed_saved_object_index_pattern';
+import { Field } from '../index_patterns_service';
 
 jest.mock('ui/registry/field_formats', () => ({
   fieldFormats: {
     getDefaultInstance: jest.fn(),
-  }
+  },
 }));
 
 jest.mock('ui/utils/mapping_setup', () => ({
@@ -36,16 +41,16 @@ jest.mock('ui/utils/mapping_setup', () => ({
     id: true,
     title: true,
     fieldFormatMap: {
-      _deserialize: jest.fn().mockImplementation(() => ([])),
+      _deserialize: jest.fn().mockImplementation(() => []),
     },
-  }))
+  })),
 }));
 
 jest.mock('ui/notify', () => ({
   toastNotifications: {
     addDanger: jest.fn(),
     addError: jest.fn(),
-  }
+  },
 }));
 
 jest.mock('ui/saved_objects', () => {
@@ -54,32 +59,32 @@ jest.mock('ui/saved_objects', () => {
   };
 });
 
-let mockFieldsFetcherResponse = [];
+let mockFieldsFetcherResponse: any[] = [];
+
 jest.mock('./_fields_fetcher', () => ({
   createFieldsFetcher: jest.fn().mockImplementation(() => ({
     fetch: jest.fn().mockImplementation(() => {
       return new Promise(resolve => resolve(mockFieldsFetcherResponse));
     }),
     every: jest.fn(),
-  }))
+  })),
 }));
 
-let object;
+let object: any = {};
+
 const savedObjectsClient = {
   create: jest.fn(),
   get: jest.fn().mockImplementation(() => object),
   update: jest.fn().mockImplementation(async (type, id, body, { version }) => {
     if (object._version !== version) {
-      throw {
+      throw new Object({
         res: {
-          status: 409
-        }
-      };
+          status: 409,
+        },
+      });
     }
-
     object.attributes.title = body.title;
     object._version += 'a';
-
     return {
       id: object._id,
       _version: object._version,
@@ -96,35 +101,44 @@ const config = {
 };
 
 const apiClient = {
+  _getUrl: jest.fn(),
   getFieldsForTimePattern: jest.fn(),
   getFieldsForWildcard: jest.fn(),
 };
 
 // helper function to create index patterns
-function create(id, payload) {
-  const indexPattern = new IndexPattern(id, cfg => config.get(cfg), savedObjectsClient, apiClient, patternCache);
+function create(id: string, payload?: any): Promise<IndexPattern> {
+  const indexPattern = new IndexPattern(
+    id,
+    (cfg: any) => config.get(cfg),
+    savedObjectsClient as any,
+    apiClient,
+    patternCache
+  );
 
   setDocsourcePayload(id, payload);
 
   return indexPattern.init();
 }
 
-function setDocsourcePayload(id, providedPayload) {
-  object = _.defaults(providedPayload || {}, stubbedSavedObjectIndexPattern(id));
+function setDocsourcePayload(id: string | null, providedPayload: any) {
+  object = defaults(providedPayload || {}, stubbedSavedObjectIndexPattern(id));
 }
 
 describe('IndexPattern', () => {
   const indexPatternId = 'test-pattern';
-  let indexPattern;
+
+  let indexPattern: IndexPattern;
+
   // create an indexPattern instance for each test
-  beforeEach(function () {
-    return create(indexPatternId).then(function (pattern) {
+  beforeEach(() => {
+    return create(indexPatternId).then((pattern: IndexPattern) => {
       indexPattern = pattern;
     });
   });
 
-  describe('api', function () {
-    it('should have expected properties', function () {
+  describe('api', () => {
+    test('should have expected properties', () => {
       expect(indexPattern).toHaveProperty('refreshFields');
       expect(indexPattern).toHaveProperty('popularizeField');
       expect(indexPattern).toHaveProperty('getScriptedFields');
@@ -140,16 +154,16 @@ describe('IndexPattern', () => {
     });
   });
 
-  describe('init', function () {
-    it('should append the found fields', function () {
+  describe('init', () => {
+    test('should append the found fields', () => {
       expect(savedObjectsClient.get).toHaveBeenCalled();
-      expect(indexPattern.fields).toHaveLength(mockLogstashFields().length);
+      expect(indexPattern.fields).toHaveLength(mockLogStashFields().length);
       expect(indexPattern.fields).toBeInstanceOf(IndexedArray);
     });
   });
 
-  describe('fields', function () {
-    it('should have expected properties on fields', function () {
+  describe('fields', () => {
+    test('should have expected properties on fields', function() {
       expect(indexPattern.fields[0]).toHaveProperty('displayName');
       expect(indexPattern.fields[0]).toHaveProperty('filterable');
       expect(indexPattern.fields[0]).toHaveProperty('format');
@@ -158,42 +172,45 @@ describe('IndexPattern', () => {
     });
   });
 
-  describe('getScriptedFields', function () {
-    it('should return all scripted fields', function () {
-      const scriptedNames = _(mockLogstashFields()).where({ scripted: true }).pluck('name').value();
-      const respNames = _.pluck(indexPattern.getScriptedFields(), 'name');
+  describe('getScriptedFields', () => {
+    test('should return all scripted fields', () => {
+      const scriptedNames = mockLogStashFields()
+        .filter((item: Field) => item.scripted === true)
+        .map((item: Field) => item.name);
+      const respNames = pluck(indexPattern.getScriptedFields(), 'name');
+
       expect(respNames).toEqual(scriptedNames);
     });
   });
 
-  describe('getNonScriptedFields', function () {
-    it('should return all non-scripted fields', function () {
-      const notScriptedNames = _(mockLogstashFields()).where({ scripted: false }).pluck('name').value();
-      const respNames = _.pluck(indexPattern.getNonScriptedFields(), 'name');
+  describe('getNonScriptedFields', () => {
+    test('should return all non-scripted fields', () => {
+      const notScriptedNames = mockLogStashFields()
+        .filter((item: Field) => item.scripted === false)
+        .map((item: Field) => item.name);
+      const respNames = pluck(indexPattern.getNonScriptedFields(), 'name');
+
       expect(respNames).toEqual(notScriptedNames);
     });
-
   });
 
-  describe('refresh fields', function () {
-    it('should fetch fields from the fieldsFetcher', async function () {
+  describe('refresh fields', () => {
+    test('should fetch fields from the fieldsFetcher', async () => {
       expect(indexPattern.fields.length).toBeGreaterThan(2);
 
-      mockFieldsFetcherResponse = [
-        { name: 'foo' },
-        { name: 'bar' }
-      ];
+      mockFieldsFetcherResponse = [{ name: 'foo' }, { name: 'bar' }];
 
       await indexPattern.refreshFields();
 
       mockFieldsFetcherResponse = [];
 
       const newFields = indexPattern.getNonScriptedFields();
+
       expect(newFields).toHaveLength(2);
       expect(newFields.map(f => f.name)).toEqual(['foo', 'bar']);
     });
 
-    it('should preserve the scripted fields', async function () {
+    test('should preserve the scripted fields', async () => {
       // add spy to indexPattern.getScriptedFields
       // sinon.spy(indexPattern, 'getScriptedFields');
 
@@ -202,13 +219,16 @@ describe('IndexPattern', () => {
 
       // called to append scripted fields to the response from mapper.getFieldsForIndexPattern
       // sinon.assert.calledOnce(indexPattern.getScriptedFields);
-      expect(indexPattern.getScriptedFields().map(f => f.name))
-        .toEqual(mockLogstashFields().filter(f => f.scripted).map(f => f.name));
+      expect(indexPattern.getScriptedFields().map(f => f.name)).toEqual(
+        mockLogStashFields()
+          .filter((f: Field) => f.scripted)
+          .map((f: Field) => f.name)
+      );
     });
   });
 
-  describe('add and remove scripted fields', function () {
-    it('should append the scripted field', function () {
+  describe('add and remove scripted fields', () => {
+    test('should append the scripted field', async () => {
       // keep a copy of the current scripted field count
       // const saveSpy = sinon.spy(indexPattern, 'save');
       const oldCount = indexPattern.getScriptedFields().length;
@@ -217,142 +237,128 @@ describe('IndexPattern', () => {
       const scriptedField = {
         name: 'new scripted field',
         script: 'false',
-        type: 'boolean'
+        type: 'boolean',
       };
-      indexPattern.addScriptedField(scriptedField.name, scriptedField.script, scriptedField.type);
+
+      await indexPattern.addScriptedField(
+        scriptedField.name,
+        scriptedField.script,
+        scriptedField.type,
+        'lang'
+      );
+
       const scriptedFields = indexPattern.getScriptedFields();
       // expect(saveSpy.callCount).to.equal(1);
       expect(scriptedFields).toHaveLength(oldCount + 1);
       expect(indexPattern.fields.byName[scriptedField.name].name).toEqual(scriptedField.name);
     });
 
-    it('should remove scripted field, by name', function () {
+    test('should remove scripted field, by name', async () => {
       // const saveSpy = sinon.spy(indexPattern, 'save');
       const scriptedFields = indexPattern.getScriptedFields();
       const oldCount = scriptedFields.length;
-      const scriptedField = _.last(scriptedFields);
+      const scriptedField = last(scriptedFields);
 
-      indexPattern.removeScriptedField(scriptedField.name);
+      await indexPattern.removeScriptedField(scriptedField.name);
 
       // expect(saveSpy.callCount).to.equal(1);
       expect(indexPattern.getScriptedFields().length).toEqual(oldCount - 1);
       expect(indexPattern.fields.byName[scriptedField.name]).toEqual(undefined);
     });
 
-    it('should not allow duplicate names', async () => {
+    test('should not allow duplicate names', async () => {
       const scriptedFields = indexPattern.getScriptedFields();
-      const scriptedField = _.last(scriptedFields);
+      const scriptedField = last(scriptedFields);
       expect.assertions(1);
       try {
-        await indexPattern.addScriptedField(scriptedField.name, '\'new script\'', 'string');
+        await indexPattern.addScriptedField(scriptedField.name, "'new script'", 'string', 'lang');
       } catch (e) {
         expect(e).toBeInstanceOf(DuplicateField);
       }
     });
   });
 
-  describe('popularizeField', function () {
-    it('should increment the popularity count by default', function () {
+  describe('popularizeField', () => {
+    test('should increment the popularity count by default', () => {
       // const saveSpy = sinon.stub(indexPattern, 'save');
-      indexPattern.fields.forEach(function (field) {
-        const oldCount = field.count;
+      indexPattern.fields.forEach(async field => {
+        const oldCount = field.count || 0;
 
-        indexPattern.popularizeField(field.name);
+        await indexPattern.popularizeField(field.name);
 
         // expect(saveSpy.callCount).to.equal(i + 1);
         expect(field.count).toEqual(oldCount + 1);
       });
     });
 
-    it('should increment the popularity count', function () {
+    test('should increment the popularity count', () => {
       // const saveSpy = sinon.stub(indexPattern, 'save');
-      indexPattern.fields.forEach(function (field) {
-        const oldCount = field.count;
+      indexPattern.fields.forEach(async field => {
+        const oldCount = field.count || 0;
         const incrementAmount = 4;
 
-        indexPattern.popularizeField(field.name, incrementAmount);
+        await indexPattern.popularizeField(field.name, incrementAmount);
 
         // expect(saveSpy.callCount).to.equal(i + 1);
         expect(field.count).toEqual(oldCount + incrementAmount);
       });
     });
 
-    it('should decrement the popularity count', function () {
-      indexPattern.fields.forEach(function (field) {
-        const oldCount = field.count;
+    test('should decrement the popularity count', () => {
+      indexPattern.fields.forEach(async field => {
+        const oldCount = field.count || 0;
         const incrementAmount = 4;
         const decrementAmount = -2;
 
-        indexPattern.popularizeField(field.name, incrementAmount);
-        indexPattern.popularizeField(field.name, decrementAmount);
+        await indexPattern.popularizeField(field.name, incrementAmount);
+        await indexPattern.popularizeField(field.name, decrementAmount);
 
         expect(field.count).toEqual(oldCount + incrementAmount + decrementAmount);
       });
     });
 
-    it('should not go below 0', function () {
-      indexPattern.fields.forEach(function (field) {
+    test('should not go below 0', () => {
+      indexPattern.fields.forEach(async field => {
         const decrementAmount = -Number.MAX_VALUE;
-        indexPattern.popularizeField(field.name, decrementAmount);
-        expect(field.count).toEqual(0);
-      });
-    });
-  });
-
-  describe('getIndex', () => {
-    it('should return the title when there is no intervalName', () => {
-      expect(indexPattern.getIndex()).toBe(indexPattern.title);
-    });
-
-    it('should convert time-based intervals to wildcards', () => {
-      const oldTitle = indexPattern.title;
-      indexPattern.intervalName = 'daily';
-
-      indexPattern.title = '[logstash-]YYYY.MM.DD';
-      expect(indexPattern.getIndex()).toBe('logstash-*');
-
-      indexPattern.title = 'YYYY.MM.DD[-logstash]';
-      expect(indexPattern.getIndex()).toBe('*-logstash');
 
-      indexPattern.title = 'YYYY[-logstash-]YYYY.MM.DD';
-      expect(indexPattern.getIndex()).toBe('*-logstash-*');
+        await indexPattern.popularizeField(field.name, decrementAmount);
 
-      indexPattern.title = 'YYYY[-logstash-]YYYY[-foo-]MM.DD';
-      expect(indexPattern.getIndex()).toBe('*-logstash-*-foo-*');
-
-      indexPattern.title = 'YYYY[-logstash-]YYYY[-foo-]MM.DD[-bar]';
-      expect(indexPattern.getIndex()).toBe('*-logstash-*-foo-*-bar');
-
-      indexPattern.title = '[logstash-]YYYY[-foo-]MM.DD[-bar]';
-      expect(indexPattern.getIndex()).toBe('logstash-*-foo-*-bar');
-
-      indexPattern.title = '[logstash]';
-      expect(indexPattern.getIndex()).toBe('logstash');
-
-      indexPattern.title = oldTitle;
-      delete indexPattern.intervalName;
+        expect(field.count).toEqual(0);
+      });
     });
   });
 
-  it('should handle version conflicts', async () => {
+  test('should handle version conflicts', async () => {
     setDocsourcePayload(null, {
-      _version: 'foo',
       _id: 'foo',
+      _version: 'foo',
       attributes: {
-        title: 'something'
-      }
+        title: 'something',
+      },
     });
     // Create a normal index pattern
-    const pattern = new IndexPattern('foo', cfg => config.get(cfg), savedObjectsClient, apiClient, patternCache);
+    const pattern = new IndexPattern(
+      'foo',
+      (cfg: any) => config.get(cfg),
+      savedObjectsClient as any,
+      apiClient,
+      patternCache
+    );
     await pattern.init();
 
-    expect(pattern.version).toBe('fooa');
+    expect(get(pattern, 'version')).toBe('fooa');
 
     // Create the same one - we're going to handle concurrency
-    const samePattern = new IndexPattern('foo', cfg => config.get(cfg), savedObjectsClient, apiClient, patternCache);
+    const samePattern = new IndexPattern(
+      'foo',
+      (cfg: any) => config.get(cfg),
+      savedObjectsClient as any,
+      apiClient,
+      patternCache
+    );
     await samePattern.init();
 
-    expect(samePattern.version).toBe('fooaa');
+    expect(get(samePattern, 'version')).toBe('fooaa');
 
     // This will conflict because samePattern did a save (from refreshFields)
     // but the resave should work fine
diff --git a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns.test.js b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns.test.ts
similarity index 68%
rename from src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns.test.js
rename to src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns.test.ts
index 039910e8d3b23..8fc5c89e5d17c 100644
--- a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns.test.js
+++ b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns.test.ts
@@ -17,66 +17,65 @@
  * under the License.
  */
 
+// eslint-disable-next-line max-classes-per-file
 import { IndexPatterns } from './index_patterns';
+import { SavedObjectsClientContract, UiSettingsClientContract } from 'kibana/public';
 
 jest.mock('../errors', () => ({
   IndexPatternMissingIndices: jest.fn(),
 }));
 
-
 jest.mock('ui/registry/field_formats', () => ({
   fieldFormats: {
     getDefaultInstance: jest.fn(),
-  }
+  },
 }));
 
 jest.mock('ui/notify', () => ({
   toastNotifications: {
     addDanger: jest.fn(),
-  }
+  },
 }));
 
 jest.mock('./index_pattern', () => {
   class IndexPattern {
     init = async () => {
       return this;
-    }
+    };
   }
 
   return {
-    IndexPattern
+    IndexPattern,
   };
 });
 
 jest.mock('./index_patterns_api_client', () => {
   class IndexPatternsApiClient {
-    getFieldsForWildcard = async () => ({})
+    getFieldsForWildcard = async () => ({});
   }
 
   return {
-    IndexPatternsApiClient
+    IndexPatternsApiClient,
   };
 });
 
-const savedObjectsClient = {
-  create: jest.fn(),
-  get: jest.fn(),
-  update: jest.fn()
-};
-
-const config = {
-  get: jest.fn(),
-};
+describe('IndexPatterns', () => {
+  let indexPatterns: IndexPatterns;
 
+  beforeEach(() => {
+    const savedObjectsClient = {} as SavedObjectsClientContract;
+    const uiSettings = {} as UiSettingsClientContract;
 
-describe('IndexPatterns', () => {
-  const indexPatterns = new IndexPatterns(config, savedObjectsClient);
+    indexPatterns = new IndexPatterns(uiSettings, savedObjectsClient);
+  });
 
-  it('does not cache gets without an id', function () {
+  test('does not cache gets without an id', () => {
     expect(indexPatterns.get()).not.toBe(indexPatterns.get());
   });
 
-  it('does cache gets for the same id', function () {
-    expect(indexPatterns.get(1)).toBe(indexPatterns.get(1));
+  test('does cache gets for the same id', () => {
+    const id = '1';
+
+    expect(indexPatterns.get(id)).toBe(indexPatterns.get(id));
   });
 });
diff --git a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.js b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.js
deleted file mode 100644
index bea4c6c489c9b..0000000000000
--- a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.js
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
- * 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 { http } from './index_patterns_api_client.test.mock';
-import { IndexPatternsApiClient } from './index_patterns_api_client';
-
-describe('IndexPatternsApiClient', () => {
-  it('uses the right URI to fetch fields for time patterns', async function () {
-    const fetchSpy = jest.spyOn(http, 'fetch').mockImplementation(() => ({}));
-    const indexPatternsApiClient = new IndexPatternsApiClient();
-    await indexPatternsApiClient.getFieldsForTimePattern();
-
-    expect(fetchSpy).toHaveBeenCalledWith('/api/index_patterns/_fields_for_time_pattern', {
-      credentials: 'same-origin',
-      headers: { 'Content-Type': 'application/json' },
-      method: 'GET',
-      prependBasePath: true,
-      query: {},
-    });
-  });
-
-  it('uses the right URI to fetch fields for wildcard', async function () {
-    const fetchSpy = jest.spyOn(http, 'fetch').mockImplementation(() => ({}));
-    const indexPatternsApiClient = new IndexPatternsApiClient();
-    await indexPatternsApiClient.getFieldsForWildcard();
-
-    expect(fetchSpy).toHaveBeenCalledWith('/api/index_patterns/_fields_for_wildcard', {
-      credentials: 'same-origin',
-      headers: { 'Content-Type': 'application/json' },
-      method: 'GET',
-      prependBasePath: true,
-      query: {},
-    });
-  });
-
-  it('uses the right URI to fetch fields for wildcard given a type', async function () {
-    const fetchSpy = jest.spyOn(http, 'fetch').mockImplementation(() => ({}));
-    const indexPatternsApiClient = new IndexPatternsApiClient();
-    await indexPatternsApiClient.getFieldsForWildcard({ type: 'rollup' });
-
-    expect(fetchSpy).toHaveBeenCalledWith('/api/index_patterns/rollup/_fields_for_wildcard', {
-      credentials: 'same-origin',
-      headers: { 'Content-Type': 'application/json' },
-      method: 'GET',
-      prependBasePath: true,
-      query: {},
-    });
-  });
-});
diff --git a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.mock.js b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.mock.ts
similarity index 99%
rename from src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.mock.js
rename to src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.mock.ts
index a793fa6a25bea..06933dc409052 100644
--- a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.mock.js
+++ b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.mock.ts
@@ -17,7 +17,6 @@
  * under the License.
  */
 
-
 import { setup } from '../../../../../../test_utils/public/http_test_setup';
 
 export const { http } = setup(injectedMetadata => {
diff --git a/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.ts b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.ts
new file mode 100644
index 0000000000000..944108e1501f1
--- /dev/null
+++ b/src/legacy/core_plugins/data/public/index_patterns/index_patterns/index_patterns_api_client.test.ts
@@ -0,0 +1,63 @@
+/*
+ * 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 { http } from './index_patterns_api_client.test.mock';
+import { IndexPatternsApiClient } from './index_patterns_api_client';
+
+const requestData = {
+  credentials: 'same-origin',
+  headers: { 'Content-Type': 'application/json' },
+  method: 'GET',
+  prependBasePath: true,
+  query: {},
+};
+
+describe('IndexPatternsApiClient', () => {
+  let fetchSpy: jest.Mock;
+  let indexPatternsApiClient: IndexPatternsApiClient;
+
+  beforeEach(() => {
+    fetchSpy = jest.spyOn(http, 'fetch').mockImplementation(() => Promise.resolve({}));
+    indexPatternsApiClient = new IndexPatternsApiClient();
+  });
+
+  test('uses the right URI to fetch fields for time patterns', async function() {
+    const expectedPath = '/api/index_patterns/_fields_for_time_pattern';
+
+    await indexPatternsApiClient.getFieldsForTimePattern();
+
+    expect(fetchSpy).toHaveBeenCalledWith(expectedPath, requestData);
+  });
+
+  test('uses the right URI to fetch fields for wildcard', async function() {
+    const expectedPath = '/api/index_patterns/_fields_for_wildcard';
+
+    await indexPatternsApiClient.getFieldsForWildcard();
+
+    expect(fetchSpy).toHaveBeenCalledWith(expectedPath, requestData);
+  });
+
+  test('uses the right URI to fetch fields for wildcard given a type', async function() {
+    const expectedPath = '/api/index_patterns/rollup/_fields_for_wildcard';
+
+    await indexPatternsApiClient.getFieldsForWildcard({ type: 'rollup' });
+
+    expect(fetchSpy).toHaveBeenCalledWith(expectedPath, requestData);
+  });
+});