fix: Correct path to file containing custom fetch function when building Mesh project

.changeset/stupid-cobras-give.md

@@ -0,0 +1,5 @@
+---
+'@graphql-mesh/config': patch
+---
+
+Fix path to file containing custom fetch function when building Mesh project

packages/config/src/utils.ts

@@ -134,7 +134,10 @@ export async function resolveCustomFetch({
     additionalPrefixes: additionalPackagePrefixes,
   });
 
-  importCode += `import fetchFn from ${JSON.stringify(moduleName)};\n`;
+  const processedModuleName = path.isAbsolute(moduleName)
+    ? moduleName
+    : path.join('..', moduleName);
+  importCode += `import fetchFn from ${JSON.stringify(processedModuleName)};\n`;
 
   return {
     fetchFn,

packages/config/test/mesh-config-sources/custom-fetch.ts

@@ -0,0 +1,6 @@
+import { MeshFetchRequestInit } from '@graphql-mesh/types';
+import { fetch } from '@whatwg-node/fetch';
+
+export default function (url: string, options?: MeshFetchRequestInit) {
+  return fetch(url, options);
+}

packages/config/test/processConfig.test.ts

@@ -0,0 +1,52 @@
+import { path as pathModule } from '@graphql-mesh/cross-helpers';
+import { writeFile } from '@graphql-mesh/utils';
+import { processConfig } from '../src/process';
+
+describe('processConfig', () => {
+  const generatedMeshConfiguration = '.mesh';
+
+  it('should be possible to load custom fetch function', async () => {
+    const config = await processConfig(
+      {
+        customFetch: './mesh-config-sources/custom-fetch.ts',
+        sources: [],
+      },
+      {
+        dir: __dirname,
+        generateCode: true,
+      },
+    );
+
+    // Verify that the code has been generated
+    expect(config).toBeDefined();
+    expect(config.importCodes).toBeDefined();
+
+    let meshConfigContent = '';
+
+    // Find the custom fetch
+    const importCodesIterator = config.importCodes.values();
+    let importCodesIteratorResult = importCodesIterator.next();
+    let includesCustomFetch;
+    while (!importCodesIteratorResult.done) {
+      if (importCodesIteratorResult.value.startsWith('import fetchFn from')) {
+        meshConfigContent = meshConfigContent.concat(importCodesIteratorResult.value, '\n');
+        includesCustomFetch = true;
+        break;
+      }
+      importCodesIteratorResult = importCodesIterator.next();
+    }
+    expect(includesCustomFetch).toBeTruthy();
+
+    expect(meshConfigContent).toBeDefined();
+
+    // Adding export of fetch function so its resolution is actually attempted
+    meshConfigContent = meshConfigContent.concat('export { fetchFn };', '\n');
+
+    // Create a .ts file with the codes and importCodes content
+    const meshConfigPath = pathModule.join(__dirname, generatedMeshConfiguration, '/index.ts');
+    await writeFile(meshConfigPath, meshConfigContent);
+
+    const { fetchFn } = await import(meshConfigPath);
+    expect(fetchFn).toBeDefined();
+  });
+});