Custom document transforms (#10509)

Co-authored-by: Lenz Weber-Tronic <[email protected]>
Co-authored-by: Ben Newman <[email protected]>

Author: 3 people

src/testing/matchers/index.d.ts

@@ -0,0 +1,15 @@
+import type { DocumentNode } from '../../core';
+
+interface ApolloCustomMatchers<R = void> {
+  /**
+   * Used to determine if two GraphQL query documents are equal to each other by
+   * comparing their printed values. The document must be parsed by `gql`.
+   */
+  toMatchDocument(document: DocumentNode): R;
+}
+
+declare global {
+  namespace jest {
+    interface Matchers<R = void> extends ApolloCustomMatchers<R> {}
+  }
+}

src/testing/matchers/index.ts

@@ -0,0 +1,6 @@
+import { expect } from '@jest/globals';
+import { toMatchDocument } from './toMatchDocument';
+
+expect.extend({
+  toMatchDocument,
+});

src/testing/matchers/toMatchDocument.ts

@@ -0,0 +1,64 @@
+import { checkDocument } from '../../utilities';
+import { print } from 'graphql';
+import type { DocumentNode } from '../../core';
+import type { MatcherFunction } from 'expect';
+
+export const toMatchDocument: MatcherFunction<[document: DocumentNode]> =
+  function (actual, document) {
+    const hint = this.utils.matcherHint('toMatchDocument');
+    const actualDocument = print(
+      validateDocument(
+        actual,
+        hint +
+          `\n\n${this.utils.RECEIVED_COLOR(
+            'received'
+          )} document must be a parsed document.`
+      )
+    );
+    const expectedDocument = print(
+      validateDocument(
+        document,
+        hint +
+          `\n\n${this.utils.EXPECTED_COLOR(
+            'expected'
+          )} document must be a parsed document.`
+      )
+    );
+
+    const pass = actualDocument === expectedDocument;
+
+    return {
+      pass,
+      message: () => {
+        const hint = this.utils.matcherHint(
+          'toMatchDocument',
+          undefined,
+          undefined,
+          { isNot: this.isNot }
+        );
+
+        if (pass) {
+          return (
+            hint +
+            '\n\n' +
+            'Received:\n\n' +
+            this.utils.RECEIVED_COLOR(actualDocument)
+          );
+        }
+
+        return (
+          hint + '\n\n' + this.utils.diff(expectedDocument, actualDocument)
+        );
+      },
+    };
+  };
+
+function validateDocument(document: unknown, message: string) {
+  try {
+    checkDocument(document as DocumentNode);
+  } catch (e) {
+    throw new Error(message);
+  }
+
+  return document as DocumentNode;
+}