test: Add tests and comments to better document any typed data structures (#1498)

* Add a test for the mutate function

* Comment out the tests

* Fixed problems with the test to reproduce issue

* Modify the cosmetic aspects of the new system test

* Add a comment about the shape of Entry types

* Clarify the comment describing the expected type

* Add a comment that describes the type required

Type for mutation that is

* Uncomment again

* Remove only

Author: danieljbruce

handwritten/bigtable/src/mutation.ts

@@ -25,6 +25,24 @@ export type ISetCell = btTypes.bigtable.v2.Mutation.ISetCell;
 export type Bytes = string | Buffer;
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export type Data = any;
+/*
+The Data type is expected to be in the following format:
+{
+  columnFamily1: {
+    column1: Cell,
+    column2: Cell
+  },
+  columnFamily2: {
+    otherColumn1: Cell,
+    otherColumn2: Cell
+  }
+}
+Where the Cell data type has the following structure:
+Uint8Array | string | {
+  value: Uint8Array|string,
+  timestamp: number|Long|string,
+}
+*/
 export interface JsonObj {
   [k: string]: string | JsonObj;
 }

handwritten/bigtable/src/table.ts

@@ -287,6 +287,14 @@ export interface MutateOptions {
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export type Entry = any;
+/*
+The Entry type is expected to be in the following format:
+{
+  columnFamily: {
+    column: Data // Data is the expected type passed into Mutation.encodeSetCell
+  }
+}
+*/
 
 export type DeleteTableCallback = (
   err: ServiceError | null,

handwritten/bigtable/system-test/bigtable.ts

@@ -33,6 +33,7 @@ import {Row} from '../src/row.js';
 import {Table} from '../src/table.js';
 import {RawFilter} from '../src/filter';
 import {generateId, PREFIX} from './common';
+import {Mutation} from '../src/mutation';
 
 describe('Bigtable', () => {
   const bigtable = new Bigtable();
@@ -1712,6 +1713,90 @@ describe('Bigtable', () => {
       });
     });
   });
+
+  describe('mutateRows entries tests', () => {
+    const table = INSTANCE.table(generateId('table'));
+
+    afterEach(async () => {
+      await table.delete();
+    });
+
+    it('should only insert one row in the table with mutate', async () => {
+      // Create table
+      const tableOptions = {
+        families: ['columnFamily'],
+      };
+      await table.create(tableOptions);
+      // Add entries
+      const entry = {
+        columnFamily: {
+          column: 1,
+        },
+      };
+      const mutation = {
+        key: 'rowKey',
+        data: entry,
+        method: Mutation.methods.INSERT,
+      };
+      const gaxOptions = {maxRetries: 4};
+      await table.mutate(mutation, {gaxOptions});
+      // Get rows and compare
+      const [rows] = await table.getRows();
+      assert.strictEqual(rows.length, 1);
+    });
+
+    it('should insert one row in the table using mutate in a similar way to how the documentation says to use insert', async () => {
+      // Create table
+      const tableOptions = {
+        families: ['columnFamily'],
+      };
+      await table.create(tableOptions);
+      // Add entries
+      const mutation = {
+        key: 'rowKey',
+        data: {
+          columnFamily: {
+            column: 1,
+          },
+        },
+        method: Mutation.methods.INSERT,
+      };
+      const gaxOptions = {maxRetries: 4};
+      await table.mutate(mutation, {gaxOptions});
+      // Get rows and compare
+      const [rows] = await table.getRows();
+      assert.strictEqual(rows.length, 1);
+    });
+
+    it('should only insert one row in the table with insert as described by the GCP documentation', async () => {
+      // Create table
+      const tableOptions = {
+        families: ['follows'],
+      };
+      await table.create(tableOptions);
+      // Add entries
+      const greetings = ['Hello World!', 'Hello Bigtable!', 'Hello Node!'];
+      const rowsToInsert = greetings.map((greeting, index) => ({
+        key: `greeting${index}`,
+        data: {
+          follows: {
+            // 'follows' is the column family
+            someColumn: {
+              // Setting the timestamp allows the client to perform retries. If
+              // server-side time is used, retries may cause multiple cells to
+              // be generated.
+              timestamp: new Date(),
+              value: greeting,
+            },
+          },
+        },
+      }));
+      await table.insert(rowsToInsert);
+      // Get rows and compare
+      const [rows] = await table.getRows();
+      assert.strictEqual(rows.length, 3);
+    });
+  });
 });
 
 function createInstanceConfig(