fix test

Author: mikeldking

js/packages/openinference-instrumentation-langchain/src/utils.ts

@@ -144,7 +144,9 @@ function formatIO({
   if (values.length === 1 && typeof values[0] === "string") {
     return {
       [valueAttribute]: values[0],
-      [mimeTypeAttribute]: MimeType.TEXT,
+      [mimeTypeAttribute]: isJSONString(values[0])
+        ? MimeType.JSON
+        : MimeType.TEXT,
     };
   }
 
@@ -495,6 +497,13 @@ function formatPromptTemplate(run: Run): PromptTemplateAttributes | null {
 function getTokenCount(maybeCount: unknown) {
   return isNumber(maybeCount) ? maybeCount : undefined;
 }
+/**
+ * A simple function that determines if a string is JSON like
+ * Note this is a rough check just to set the MIME type
+ */
+function isJSONString(str: string) {
+  return str.startsWith("{") && str.endsWith("}");
+}
 
 /**
  * Formats the token counts of a langchain run into OpenInference attributes.

js/packages/openinference-instrumentation-langchain/test/langchainV3.test.ts

@@ -541,11 +541,11 @@ describe("LangChainInstrumentation", () => {
         span.attributes[OPENINFERENCE_SPAN_KIND] === OpenInferenceSpanKind.TOOL,
     );
     expect(toolSpan).toBeDefined();
-    expect(toolSpan?.attributes).toStrictEqual({
+    expect(toolSpan?.attributes).toMatchObject({
       [OPENINFERENCE_SPAN_KIND]: OpenInferenceSpanKind.TOOL,
       [TOOL_NAME]: "test_tool",
-      [INPUT_VALUE]: "hello",
-      [INPUT_MIME_TYPE]: "text/plain",
+      [INPUT_VALUE]: '{"input":"hello"}',
+      [INPUT_MIME_TYPE]: "application/json",
       [OUTPUT_VALUE]: "this is a test tool",
       [OUTPUT_MIME_TYPE]: "text/plain",
       metadata: "{}",