config-loader: lazy load typescript-json-schema

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/calm-boxes-smell.md

@@ -0,0 +1,5 @@
+---
+'@backstage/config-loader': patch
+---
+
+The `typescript-json-schema` dependency that is used during schema collection is now lazy loaded, as it eagerly loads in the TypeScript compiler.

packages/config-loader/src/lib/schema/collect.test.ts

@@ -28,6 +28,9 @@ const mockSchema = {
   },
 };
 
+// Gotta make sure this is in the compiler cache before we start mocking the filesystem
+require('typescript-json-schema');
+
 // We need to load in actual TS libraries when using mock-fs.
 // This lookup is to allow the `typescript` dependency to exist either
 // at top level or inside node_modules of typescript-json-schema

packages/config-loader/src/lib/schema/collect.ts

@@ -22,7 +22,6 @@ import {
   sep,
 } from 'path';
 import { ConfigSchemaPackageEntry } from './types';
-import { getProgramFromFiles, generateSchema } from 'typescript-json-schema';
 import { JsonObject } from '@backstage/types';
 import { assertError } from '@backstage/errors';
 
@@ -149,7 +148,7 @@ export async function collectConfigSchemas(
     ...packagePaths.map(path => processItem({ name: path, packagePath: path })),
   ]);
 
-  const tsSchemas = compileTsSchemas(tsSchemaPaths);
+  const tsSchemas = await compileTsSchemas(tsSchemaPaths);
 
   return schemas.concat(tsSchemas);
 }
@@ -157,11 +156,17 @@ export async function collectConfigSchemas(
 // This handles the support of TypeScript .d.ts config schema declarations.
 // We collect all typescript schema definition and compile them all in one go.
 // This is much faster than compiling them separately.
-function compileTsSchemas(paths: string[]) {
+async function compileTsSchemas(paths: string[]) {
   if (paths.length === 0) {
     return [];
   }
 
+  // Lazy loaded, because this brings up all of TypeScript and we don't
+  // want that eagerly loaded in tests
+  const { getProgramFromFiles, generateSchema } = await import(
+    'typescript-json-schema'
+  );
+
   const program = getProgramFromFiles(paths, {
     incremental: false,
     isolatedModules: true,