transformInputValue chokes on queries that rely on array input coercion

[leemhenson]

Issue workflow progress

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• 2. A failing test has been provided
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Describe the bug

transformInputValue fails with:

TypeError: value.map is not a function at transformInputValue (.../node_modules/@graphql-tools/utils/cjs/transformInputValue.js)

when the client is depending on the array input field coercion.

To Reproduce

I'm using graphql-tools to build a stitched schema using graphql-mesh. I have an upstream graphql server that accepts a query with an input type, and the input type contains a field with an array type. E.g.

query {
  someField(input: SomeInput): String
}

input SomeInput {
  fieldX: [String]
}

Some existing code in the application is sending fieldX: "valueY" instead of fieldX: ["valueY"], but now that I'm sending that query to my new graphql-mesh-based server it hits transformInputValue because I'm using a rename transform to rename the field.

Expected behavior

transformInputValue should check to see if the incoming value is an array before mapping over it.

Environment:

• OS: MacOS
• @graphql-tools/utils: 8.8.0
• NodeJS: 16

Additional context

[leemhenson]

Here's the offending line:

https://github.com/ardatan/graphql-tools/blob/master/packages/utils/src/transformInputValue.ts#L20-L22

If I want to write a PR for this, what's the best test suite to add a test to? Nothing obviously directly targets that transformInputValue.ts file.

[ardatan]

You can create a PR that fixes it so maybe we can add unit tests with some transforms to reproduce that.
Thanks 🙏