[VisBuilder] Adds field unit tests (opensearch-project#3211)

* Adds field tests

Signed-off-by: Ashwin P Chandran <ashwinpc@amazon.com>

* Adds changelog

Signed-off-by: Ashwin P Chandran <ashwinpc@amazon.com>

Signed-off-by: Ashwin P Chandran <ashwinpc@amazon.com>
Signed-off-by: David Sinclair <david@sinclair.tech>

CHANGELOG.md

@@ -133,6 +133,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Make tests covering plugin installation on cluster snapshots work across platforms ([#2994](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2994))
 - Correct the linting logic for `no-restricted-path` to ignore trailing slashes ([#3020](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3020))
 - [Tests] Bumps `chromedriver` to v107 ([#3017](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3017))
+- [Vis Builder] Adds field unit tests ([#3211](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3211))
 
 ## [2.x]
 

src/plugins/vis_builder/public/application/components/data_tab/utils/get_available_fields.test.ts

@@ -0,0 +1,80 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { FieldSpec } from '../../../../../../data/common';
+import { IndexPatternField, OSD_FIELD_TYPES } from '../../../../../../data/public';
+import { getAvailableFields } from './get_available_fields';
+
+describe('getAvailableFields', () => {
+  const createIndexFields = (fields: Array<Partial<FieldSpec>>) =>
+    fields.map(
+      (field) =>
+        new IndexPatternField(
+          {
+            aggregatable: true,
+            name: 'field 1',
+            searchable: false,
+            type: OSD_FIELD_TYPES.STRING,
+            ...field,
+          },
+          field.name || 'field'
+        )
+    );
+
+  test('should return only aggregateable fields by default', () => {
+    const fields = createIndexFields([
+      {
+        name: 'field 1',
+      },
+      {
+        aggregatable: false,
+        name: 'field 2',
+      },
+      {
+        scripted: true,
+        name: 'field 3',
+      },
+      {
+        name: 'field 4',
+        subType: {
+          nested: { path: 'something' },
+        },
+      },
+    ]);
+
+    expect(getAvailableFields(fields).length).toBe(1);
+  });
+
+  test('should return all fields if filterFieldTypes was not specified', () => {
+    const fields = createIndexFields([
+      {
+        name: 'field 1',
+      },
+      {
+        name: 'field 2',
+      },
+    ]);
+
+    expect(getAvailableFields(fields).length).toBe(2);
+  });
+
+  test('should filterFieldTypes', () => {
+    const fields = createIndexFields([
+      {
+        name: 'field 1',
+      },
+      {
+        name: 'field 2',
+        type: OSD_FIELD_TYPES.BOOLEAN,
+      },
+      {
+        name: 'field 3',
+        type: OSD_FIELD_TYPES.BOOLEAN,
+      },
+    ]);
+
+    expect(getAvailableFields(fields, OSD_FIELD_TYPES.BOOLEAN).length).toBe(2);
+  });
+});

src/plugins/vis_builder/public/application/components/data_tab/utils/get_field_details.test.ts

@@ -0,0 +1,52 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// @ts-ignore
+import realHits from 'fixtures/real_hits.js';
+// @ts-ignore
+import stubbedLogstashFields from 'fixtures/logstash_fields';
+import { coreMock } from '../../../../../../../core/public/mocks';
+import { getStubIndexPattern } from '../../../../../../data/public/test_utils';
+import { getFieldDetails } from './get_field_details';
+import _ from 'lodash';
+
+describe('getFieldDetails', () => {
+  const indexPattern = getStubIndexPattern(
+    'logstash-*',
+    (cfg: any) => cfg,
+    'time',
+    stubbedLogstashFields(),
+    coreMock.createSetup()
+  );
+
+  test('should have error if index pattern is missing', () => {
+    const details = getFieldDetails(indexPattern.fields[0], []);
+
+    expect(details.total).toBe(0);
+    expect(details.error).toMatchInlineSnapshot(`"Index pattern not specified."`);
+  });
+
+  test('should have error if there are no hits', () => {
+    const details = getFieldDetails(indexPattern.fields[0], [], indexPattern);
+
+    expect(details.total).toBe(0);
+    expect(details.error).toMatchInlineSnapshot(
+      `"No documents match the selected query and filters. Try increasing time range or removing filters."`
+    );
+  });
+
+  test('should show details if hits are available for the index pattern field', () => {
+    const details = getFieldDetails(
+      indexPattern.fields[0],
+      _.each(_.cloneDeep(realHits), (hit) => indexPattern.flattenHit(hit)),
+      indexPattern
+    );
+
+    expect(details.exists).toBe(20);
+    expect(details.total).toBe(20);
+    expect(details.buckets.length).toBe(5);
+    expect(details.error).toBe('');
+  });
+});