Assignment logging (#3)

* implement assignment logger

* generated docs

* 0.0.2

docs/js-client-sdk.iassignmentevent.experiment.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) &gt; [experiment](./js-client-sdk.iassignmentevent.experiment.md)
+
+## IAssignmentEvent.experiment property
+
+An Eppo experiment key
+
+<b>Signature:</b>
+
+```typescript
+experiment: string;
+```

docs/js-client-sdk.iassignmentevent.md

@@ -0,0 +1,24 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentEvent](./js-client-sdk.iassignmentevent.md)
+
+## IAssignmentEvent interface
+
+Holds data about the variation a subject was assigned to.
+
+<b>Signature:</b>
+
+```typescript
+export interface IAssignmentEvent 
+```
+
+## Properties
+
+|  Property | Type | Description |
+|  --- | --- | --- |
+|  [experiment](./js-client-sdk.iassignmentevent.experiment.md) | string | An Eppo experiment key |
+|  [subject](./js-client-sdk.iassignmentevent.subject.md) | string | The entity or user that was assigned to a variation |
+|  [subjectAttributes](./js-client-sdk.iassignmentevent.subjectattributes.md) | Record&lt;string, any&gt; |  |
+|  [timestamp](./js-client-sdk.iassignmentevent.timestamp.md) | string | The time the subject was exposed to the variation. |
+|  [variation](./js-client-sdk.iassignmentevent.variation.md) | string | The assigned variation |
+

docs/js-client-sdk.iassignmentevent.subject.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) &gt; [subject](./js-client-sdk.iassignmentevent.subject.md)
+
+## IAssignmentEvent.subject property
+
+The entity or user that was assigned to a variation
+
+<b>Signature:</b>
+
+```typescript
+subject: string;
+```

docs/js-client-sdk.iassignmentevent.subjectattributes.md

@@ -0,0 +1,11 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) &gt; [subjectAttributes](./js-client-sdk.iassignmentevent.subjectattributes.md)
+
+## IAssignmentEvent.subjectAttributes property
+
+<b>Signature:</b>
+
+```typescript
+subjectAttributes: Record<string, any>;
+```

docs/js-client-sdk.iassignmentevent.timestamp.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) &gt; [timestamp](./js-client-sdk.iassignmentevent.timestamp.md)
+
+## IAssignmentEvent.timestamp property
+
+The time the subject was exposed to the variation.
+
+<b>Signature:</b>
+
+```typescript
+timestamp: string;
+```

docs/js-client-sdk.iassignmentevent.variation.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) &gt; [variation](./js-client-sdk.iassignmentevent.variation.md)
+
+## IAssignmentEvent.variation property
+
+The assigned variation
+
+<b>Signature:</b>
+
+```typescript
+variation: string;
+```

docs/js-client-sdk.iassignmentlogger.logassignment.md

@@ -0,0 +1,24 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentLogger](./js-client-sdk.iassignmentlogger.md) &gt; [logAssignment](./js-client-sdk.iassignmentlogger.logassignment.md)
+
+## IAssignmentLogger.logAssignment() method
+
+Invoked when a subject is assigned to an experiment variation.
+
+<b>Signature:</b>
+
+```typescript
+logAssignment(assignment: IAssignmentEvent): void;
+```
+
+## Parameters
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  assignment | [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) | holds the variation an experiment subject was assigned to |
+
+<b>Returns:</b>
+
+void
+

docs/js-client-sdk.iassignmentlogger.md

@@ -0,0 +1,20 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IAssignmentLogger](./js-client-sdk.iassignmentlogger.md)
+
+## IAssignmentLogger interface
+
+Implement this interface log variation assignments to your data warehouse.
+
+<b>Signature:</b>
+
+```typescript
+export interface IAssignmentLogger 
+```
+
+## Methods
+
+|  Method | Description |
+|  --- | --- |
+|  [logAssignment(assignment)](./js-client-sdk.iassignmentlogger.logassignment.md) | Invoked when a subject is assigned to an experiment variation. |
+

docs/js-client-sdk.iclientconfig.assignmentlogger.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [@eppo/js-client-sdk](./js-client-sdk.md) &gt; [IClientConfig](./js-client-sdk.iclientconfig.md) &gt; [assignmentLogger](./js-client-sdk.iclientconfig.assignmentlogger.md)
+
+## IClientConfig.assignmentLogger property
+
+Pass a logging implementation to send variation assignments to your data warehouse.
+
+<b>Signature:</b>
+
+```typescript
+assignmentLogger?: IAssignmentLogger;
+```

docs/js-client-sdk.iclientconfig.md

@@ -17,5 +17,6 @@ export interface IClientConfig
 |  Property | Type | Description |
 |  --- | --- | --- |
 |  [apiKey](./js-client-sdk.iclientconfig.apikey.md) | string | Eppo API key |
+|  [assignmentLogger?](./js-client-sdk.iclientconfig.assignmentlogger.md) | [IAssignmentLogger](./js-client-sdk.iassignmentlogger.md) | <i>(Optional)</i> Pass a logging implementation to send variation assignments to your data warehouse. |
 |  [baseUrl?](./js-client-sdk.iclientconfig.baseurl.md) | string | <i>(Optional)</i> Base URL of the Eppo API. Clients should use the default setting in most cases. |
 

docs/js-client-sdk.md

@@ -15,6 +15,8 @@
 
 |  Interface | Description |
 |  --- | --- |
+|  [IAssignmentEvent](./js-client-sdk.iassignmentevent.md) | Holds data about the variation a subject was assigned to. |
+|  [IAssignmentLogger](./js-client-sdk.iassignmentlogger.md) | Implement this interface log variation assignments to your data warehouse. |
 |  [IClientConfig](./js-client-sdk.iclientconfig.md) | Configuration used for initializing the Eppo client |
 |  [IEppoClient](./js-client-sdk.ieppoclient.md) | Client for assigning experiment variations. |
 

js-client-sdk.api.md

@@ -7,9 +7,25 @@
 // @public
 export function getInstance(): IEppoClient;
 
+// @public
+export interface IAssignmentEvent {
+    experiment: string;
+    subject: string;
+    // (undocumented)
+    subjectAttributes: Record<string, any>;
+    timestamp: string;
+    variation: string;
+}
+
+// @public
+export interface IAssignmentLogger {
+    logAssignment(assignment: IAssignmentEvent): void;
+}
+
 // @public
 export interface IClientConfig {
     apiKey: string;
+    assignmentLogger?: IAssignmentLogger;
     baseUrl?: string;
 }
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk",
-  "version": "0.0.1",
+  "version": "0.0.2",
   "description": "Eppo SDK for client-side JavaScript applications",
   "main": "dist/index.js",
   "files": [
@@ -16,7 +16,7 @@
     "typecheck": "tsc",
     "test": "yarn test:unit",
     "test:unit": "NODE_ENV=test jest '.*\\.spec\\.ts'",
-    "docs": "api-extractor run --local --verbose && api-documenter markdown -i ./temp -o ./docs"
+    "docs": "tsc && api-extractor run --local --verbose && api-documenter markdown -i ./temp -o ./docs"
   },
   "repository": {
     "type": "git",

src/assignment-logger.ts

@@ -0,0 +1,41 @@
+/**
+ * Holds data about the variation a subject was assigned to.
+ * @public
+ */
+export interface IAssignmentEvent {
+  /**
+   * An Eppo experiment key
+   */
+  experiment: string;
+
+  /**
+   * The assigned variation
+   */
+  variation: string;
+
+  /**
+   * The entity or user that was assigned to a variation
+   */
+  subject: string;
+
+  /**
+   * The time the subject was exposed to the variation.
+   */
+  timestamp: string;
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  subjectAttributes: Record<string, any>;
+}
+
+/**
+ * Implement this interface log variation assignments to your data warehouse.
+ * @public
+ */
+export interface IAssignmentLogger {
+  /**
+   * Invoked when a subject is assigned to an experiment variation.
+   * @param assignment holds the variation an experiment subject was assigned to
+   * @public
+   */
+  logAssignment(assignment: IAssignmentEvent): void;
+}

src/eppo-client.spec.ts

@@ -6,6 +6,7 @@ import mock from 'xhr-mock';
 
 import { IAssignmentTestCase, readAssignmentTestData } from '../test/testHelpers';
 
+import { IAssignmentLogger } from './assignment-logger';
 import EppoClient from './eppo-client';
 import { IExperimentConfiguration } from './experiment/experiment-configuration';
 import ExperimentConfigurationRequestor from './experiment/experiment-configuration-requestor';
@@ -41,6 +42,30 @@ describe('EppoClient E2E test', () => {
     mock.teardown();
   });
 
+  const mockVariations = [
+    {
+      name: 'control',
+      shardRange: {
+        start: 0,
+        end: 33,
+      },
+    },
+    {
+      name: 'variant-1',
+      shardRange: {
+        start: 34,
+        end: 66,
+      },
+    },
+    {
+      name: 'variant-2',
+      shardRange: {
+        start: 67,
+        end: 100,
+      },
+    },
+  ];
+
   describe('getAssignment', () => {
     it.each(readAssignmentTestData())(
       'test variation assignment splits',
@@ -73,29 +98,7 @@ describe('EppoClient E2E test', () => {
       percentExposure: 1,
       enabled: true,
       subjectShards: 100,
-      variations: [
-        {
-          name: 'control',
-          shardRange: {
-            start: 0,
-            end: 33,
-          },
-        },
-        {
-          name: 'variant-1',
-          shardRange: {
-            start: 34,
-            end: 66,
-          },
-        },
-        {
-          name: 'variant-2',
-          shardRange: {
-            start: 67,
-            end: 100,
-          },
-        },
-      ],
+      variations: mockVariations,
       overrides: {
         a90ea45116d251a43da56e03d3dd7275: 'variant-2',
       },
@@ -105,6 +108,45 @@ describe('EppoClient E2E test', () => {
     expect(assignment).toEqual('variant-2');
   });
 
+  it('logs variation assignment', () => {
+    const mockConfigRequestor = td.object<ExperimentConfigurationRequestor>();
+    const mockLogger = td.object<IAssignmentLogger>();
+    const experiment = 'experiment_5';
+    td.when(mockConfigRequestor.getConfiguration(experiment)).thenReturn({
+      name: experiment,
+      percentExposure: 1,
+      enabled: true,
+      subjectShards: 100,
+      variations: mockVariations,
+      overrides: {},
+    });
+    const subjectAttributes = { foo: 3 };
+    const client = new EppoClient(mockConfigRequestor, mockLogger);
+    const assignment = client.getAssignment('subject-1', experiment, subjectAttributes);
+    expect(assignment).toEqual('control');
+    expect(td.explain(mockLogger.logAssignment).callCount).toEqual(1);
+    expect(td.explain(mockLogger.logAssignment).calls[0].args[0].subject).toEqual('subject-1');
+  });
+
+  it('handles logging exception', () => {
+    const mockConfigRequestor = td.object<ExperimentConfigurationRequestor>();
+    const mockLogger = td.object<IAssignmentLogger>();
+    const experiment = 'experiment_5';
+    td.when(mockLogger.logAssignment(td.matchers.anything())).thenThrow(new Error('logging error'));
+    td.when(mockConfigRequestor.getConfiguration(experiment)).thenReturn({
+      name: experiment,
+      percentExposure: 1,
+      enabled: true,
+      subjectShards: 100,
+      variations: mockVariations,
+      overrides: {},
+    });
+    const subjectAttributes = { foo: 3 };
+    const client = new EppoClient(mockConfigRequestor, mockLogger);
+    const assignment = client.getAssignment('subject-1', experiment, subjectAttributes);
+    expect(assignment).toEqual('control');
+  });
+
   it('only returns variation if subject matches rules', () => {
     const mockConfigRequestor = td.object<ExperimentConfigurationRequestor>();
     const experiment = 'experiment_5';
@@ -113,22 +155,7 @@ describe('EppoClient E2E test', () => {
       percentExposure: 1,
       enabled: true,
       subjectShards: 100,
-      variations: [
-        {
-          name: 'control',
-          shardRange: {
-            start: 0,
-            end: 50,
-          },
-        },
-        {
-          name: 'treatment',
-          shardRange: {
-            start: 50,
-            end: 100,
-          },
-        },
-      ],
+      variations: mockVariations,
       overrides: {},
       rules: [
         {