SchemaFaker False Issue How To Fix Random Values In Openapi-to-postmanv2

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In the realm of API development and testing, generating deterministic examples from OpenAPI specifications is crucial for maintaining consistency and stability. The openapi-to-postmanv2 library is a valuable tool for converting OpenAPI specifications into Postman collections. However, an issue arises when the schemaFaker option is set to false, yet the library continues to generate random property names and values for certain schema patterns. This article delves into this problem, its root causes, impact, and potential solutions, providing a comprehensive guide for developers and testers encountering this challenge.

Problem Description

The core problem lies in the unexpected behavior of openapi-to-postmanv2 when the schemaFaker option is disabled. The expectation is that with schemaFaker: false, the generated examples should adhere strictly to the schema placeholders, such as <string>, <number>, and so on, without introducing any randomness. However, the library deviates from this expectation by generating random property names and values for specific schema patterns, making the output non-deterministic across multiple runs. This behavior contradicts the intended purpose of disabling the schema faker, which is to ensure predictable and consistent output.

Expected Behavior

When the schemaFaker option is set to false, the anticipated behavior is that all generated examples should be deterministic. This means that the output should consistently use schema placeholders without any random variations. For instance, a string property should be represented by <string>, a number property by <number>, and so forth. The absence of random property names and values is essential for maintaining a stable and predictable testing environment. This deterministic behavior allows developers to rely on the generated examples for consistent testing and documentation purposes.

Actual Behavior

Despite setting schemaFaker to false, the library exhibits the undesirable behavior of generating random property names and values. This issue manifests particularly in schemas that include additionalProperties and complex structures. For example, when a schema defines an object with additionalProperties: true or additionalProperties: { type: "string" }, the generated examples may include random property names like "amet_04", "sit_2", or "fugiatd5". This randomness undermines the determinism expected when schemaFaker is disabled, leading to inconsistencies and potential issues in automated testing and integration processes. The library's failure to adhere to the schemaFaker: false setting complicates the process of generating reliable Postman collections from OpenAPI specifications.

Minimal Reproducible Example

To illustrate this issue, consider the following minimal reproducible example. This example includes an OpenAPI schema and JavaScript code that demonstrates how the openapi-to-postmanv2 library generates random property names even when schemaFaker is set to false. By examining this example, developers can gain a clear understanding of the problem and its context.

OpenAPI Schema

openapi: 3.0.3
info:
 title: Test API
 version: 1.0.0
paths:
 /test:
 post:
 requestBody:
 content:
 application/json:
 schema:
 type: object
 properties:
 publicKey:
 type: object
 additionalProperties:
 type: string
 responses:
 '200':
 description: Success
 content:
 application/json:
 schema:
 type: object
 properties:
 data:
 type: object
 additionalProperties: true

This OpenAPI schema defines a simple API with a POST endpoint /test. The request body schema includes an object named publicKey with additionalProperties of type string. The response schema includes an object named data with additionalProperties set to true. These additionalProperties definitions are key to triggering the issue.

Test Code

const { convert } = require('openapi-to-postmanv2');

const openapiSpec = {
 // ... OpenAPI spec from above
};

// Convert with schemaFaker disabled
convert(
 { type: 'string', data: JSON.stringify(openapiSpec) },
 {
 schemaFaker: false,
 exampleParametersResolution: 'Schema',
 requestParametersResolution: 'Schema'
 },
 (err, result) => {
 if (err) {
 console.error(err);
 return;
 }

 // Run this multiple times - you'll see different property names
 console.log(JSON.stringify(result.collection, null, 2));
 }
);

This JavaScript code uses the openapi-to-postmanv2 library to convert the OpenAPI specification into a Postman collection. The schemaFaker option is explicitly set to false. The code then logs the generated collection to the console. Running this code multiple times will reveal the issue.

Output Examples

When the test code is executed multiple times, the output will demonstrate the generation of random property names. Here are a few examples of the output:

Run 1:

{
 "body": {
 "mode": "raw",
 "raw": "{\n \"publicKey\": {\n \"amet_04\": \"<string>\"\n }\n }"
 }
}

Run 2:

{
 "body": {
 "mode": "raw",
 "raw": "{\n \"publicKey\": {\n \"sit_2\": \"<string>\"\n }\n }"
 }
}

Run 3:

{
 "body": {
 "mode": "raw",
 "raw": "{\n \"publicKey\": {\n \"fugiatd5\": \"<string>\"\n }\n }"
 }
}

As shown in these examples, the property names within the publicKey object (e.g., amet_04, sit_2, fugiatd5) are randomly generated each time the code is executed. This randomness occurs despite schemaFaker being set to false, highlighting the core issue.

Root Cause

The root cause of this issue lies in how openapi-to-postmanv2 handles schemas with additionalProperties, complex anyOf/oneOf structures, and objects without explicit property definitions. Even when schemaFaker is disabled, the library's logic for generating examples in these scenarios still introduces randomness. Specifically, the library generates random property names for schemas that include additionalProperties: true or additionalProperties: { type: "string" }. Additionally, complex anyOf/oneOf structures and objects lacking explicit property definitions can trigger this behavior, leading to non-deterministic output. Understanding these specific schema patterns is crucial for addressing the issue and implementing effective solutions.

Impact

The impact of this issue is significant, particularly in scenarios where deterministic Postman collections are essential. The generation of random property names makes it impossible to achieve consistent and predictable results across multiple runs. This inconsistency can lead to several problems, including:

  • Unnecessary Git Diffs: Random changes in the generated collections result in large and noisy git diffs, making it difficult to track meaningful changes and collaborate effectively.
  • Build Instability in CI/CD Pipelines: In continuous integration and continuous deployment (CI/CD) pipelines, the non-deterministic nature of the generated collections can cause build failures and instability, as tests may pass or fail based on the random property names.
  • Difficulty in Version Control Tracking: The constant changes in the generated collections complicate version control, making it challenging to maintain a clear history of changes and revert to previous versions if necessary.

These impacts highlight the importance of resolving this issue to ensure the reliability and maintainability of API testing and development workflows.

Environment

This issue is not specific to a particular environment and can occur across various setups. The following factors are generally consistent:

  • openapi-to-postmanv2 version: (latest)
  • Node.js version: (varies)
  • Operating System: (any)

The issue's universality across different environments underscores its significance and the need for a comprehensive solution.

Suggested Fix

To address this issue effectively, the openapi-to-postmanv2 library should be modified to adhere to the schemaFaker: false setting more strictly. The suggested fix involves the following key improvements:

  1. Consistent Placeholder Property Names for additionalProperties: When schemaFaker is disabled, the library should use consistent placeholder property names for additionalProperties. For example, instead of generating random names, it could use a predefined name like "<property>": "<string>".
  2. Avoid Generating Any Random Strings or Property Names: The library should be refactored to eliminate any logic that generates random strings or property names when schemaFaker is set to false. This requires a thorough review of the code to identify and remove all sources of randomness.
  3. Provide a Deterministic Fallback for All Schema Patterns: For all schema patterns, including those with additionalProperties, complex anyOf/oneOf structures, and objects without explicit property definitions, the library should provide a deterministic fallback. This ensures consistent output regardless of the schema's complexity.

Implementing these fixes will significantly improve the reliability and predictability of openapi-to-postmanv2, making it a more valuable tool for API development and testing.

Workaround

Currently, there is no complete workaround for this issue. While users can attempt to post-process the generated collection to normalize property names, this approach is complex, error-prone, and not ideal for automated workflows. The manual effort required to normalize property names can be time-consuming and may introduce new errors. Therefore, a proper fix within the openapi-to-postmanv2 library is the most effective solution. Until such a fix is available, users may need to carefully review and adjust the generated collections, which adds an extra step to their API development process.

The issue of openapi-to-postmanv2 generating random values despite schemaFaker: false presents a significant challenge for developers and testers. The non-deterministic output can lead to unnecessary git diffs, build instability in CI/CD pipelines, and difficulties in version control tracking. Understanding the root cause, which lies in the handling of schemas with additionalProperties and complex structures, is crucial for addressing the problem. The suggested fix involves using consistent placeholder property names, avoiding random string generation, and providing deterministic fallbacks for all schema patterns. While a complete workaround is lacking, implementing these improvements will greatly enhance the reliability and predictability of openapi-to-postmanv2. By addressing this issue, the library can better serve the needs of API development and testing communities, ensuring consistent and dependable results.