test: improve schema validation in tests

This commit exposes the validateModelSchema() function from
the GraphQL Transformer core. This function is very helpful
for validating the Transformer output schema's correctness.
This commit also applies the validation to @predictions v2
test suite.

packages/amplify-graphql-predictions-transformer/src/__tests__/amplify-graphql-predictions-transformer.test.ts

@@ -1,6 +1,6 @@
 'use strict';
 import { anything, countResources, expect as cdkExpect, haveResourceLike } from '@aws-cdk/assert';
-import { GraphQLTransform } from '@aws-amplify/graphql-transformer-core';
+import { GraphQLTransform, validateModelSchema } from '@aws-amplify/graphql-transformer-core';
 import { parse } from 'graphql';
 import { PredictionsTransformer } from '..';
 
@@ -14,6 +14,7 @@ test('does not generate any resources if @predictions is unused', () => {
   });
 
   const out = transformer.transform(schema);
+  validateModelSchema(parse(out.schema));
   expect(out).toBeDefined();
   expect(out.stacks).toBeDefined();
   expect(out.stacks.PredictionsDirectiveStack).toEqual(undefined);
@@ -31,7 +32,7 @@ test('lambda function is added to pipeline when lambda dependent action is added
   const out = transformer.transform(validSchema);
   expect(out).toBeDefined();
   expect(out.stacks).toBeDefined();
-  parse(out.schema);
+  validateModelSchema(parse(out.schema));
   expect(out.schema).toMatchSnapshot();
   const stack = out.stacks.PredictionsDirectiveStack;
   expect(stack).toBeDefined();
@@ -157,7 +158,7 @@ test('return type is a list based on the action', () => {
   const out = transformer.transform(validSchema);
   expect(out).toBeDefined();
   expect(out.stacks).toBeDefined();
-  parse(out.schema);
+  validateModelSchema(parse(out.schema));
   expect(out.schema).toMatchSnapshot();
   const stack = out.stacks.PredictionsDirectiveStack;
   expect(stack).toBeDefined();
@@ -186,7 +187,7 @@ test('can use actions individually and in supported sequences', () => {
   const out = transformer.transform(validSchema);
   expect(out).toBeDefined();
   expect(out.stacks).toBeDefined();
-  parse(out.schema);
+  validateModelSchema(parse(out.schema));
   expect(out.schema).toMatchSnapshot();
   const stack = out.stacks.PredictionsDirectiveStack;
   expect(stack).toBeDefined();

packages/amplify-graphql-transformer-core/src/index.ts

@@ -14,6 +14,7 @@ export {
   UserPoolConfig,
 } from './transformation';
 export { DeploymentResources } from './transformation/types';
+export { validateModelSchema } from './transformation/validation';
 export {
   ConflictDetectionType,
   ConflictHandlerType,