fix(node): Relax EmbeddingFunction type guard (#370)

node/src/embedding/embedding_function.ts

@@ -28,7 +28,6 @@ export interface EmbeddingFunction<T> {
 }
 
 export function isEmbeddingFunction<T> (value: any): value is EmbeddingFunction<T> {
-  return Object.keys(value).length === 2 &&
-      typeof value.sourceColumn === 'string' &&
+  return typeof value.sourceColumn === 'string' &&
       typeof value.embed === 'function'
 }

node/src/test/embedding/openai.ts

@@ -16,6 +16,7 @@ import { describe } from 'mocha'
 import { assert } from 'chai'
 
 import { OpenAIEmbeddingFunction } from '../../embedding/openai'
+import { isEmbeddingFunction } from '../../embedding/embedding_function'
 
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { OpenAIApi } = require('openai')
@@ -47,4 +48,10 @@ describe('OpenAPIEmbeddings', function () {
       assert.deepEqual(vectors[1], stubValue.data.data[1].embedding)
     })
   })
+
+  describe('isEmbeddingFunction', function () {
+    it('should match the isEmbeddingFunction guard', function () {
+      assert.isTrue(isEmbeddingFunction(new OpenAIEmbeddingFunction('text', 'sk-key')))
+    })
+  })
 })