start adding tests

src/utilities/__tests__/mapSchemaConfig-test.ts

@@ -0,0 +1,70 @@
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { expectJSON } from '../../__testUtils__/expectJSON.js';
+
+import type { GraphQLNamedType } from '../../type/index.js';
+import type { GraphQLSchemaNormalizedConfig } from '../../type/schema.js';
+
+import { buildSchema } from '../buildASTSchema.js';
+import { mapSchemaConfig, SchemaElementKind } from '../mapSchemaConfig.js';
+
+function toTypeMap(types: ReadonlyArray<GraphQLNamedType>) {
+  const typeMap = Object.create(null);
+  for (const type of types) {
+    typeMap[type.name] = type;
+  }
+  return typeMap;
+}
+
+describe('mapSchemaConfig', () => {
+  it('returns the original config when no mappers are included', () => {
+    const schema = buildSchema('type Query');
+    const schemaConfig = schema.toConfig();
+    const newSchemaConfig = mapSchemaConfig(schemaConfig, () => ({}));
+    expectJSON(newSchemaConfig).toDeepEqual(schemaConfig);
+  });
+
+  it('returns a new schema config when using a schema mapper', () => {
+    const schema = buildSchema('type Query');
+    const schemaConfig = schema.toConfig();
+    const schemaConfigWithDescription = {
+      ...schemaConfig,
+      description: 'New description',
+    };
+
+    const newSchemaConfig = mapSchemaConfig(schema.toConfig(), () => ({
+      [SchemaElementKind.SCHEMA]: () => schemaConfigWithDescription,
+    }));
+
+    expect(schemaConfigWithDescription).to.equal(newSchemaConfig);
+  });
+
+  it('executes schema mappers last such that they receive mapped types', () => {
+    const schema = buildSchema('type Query');
+    const schemaTypeMap = schema.getTypeMap();
+    const schemaConfig = schema.toConfig();
+    const schemaConfigWithDescription = {
+      ...schemaConfig,
+      description: 'New description',
+    };
+
+    function schemaMapper(config: GraphQLSchemaNormalizedConfig) {
+      expect(config).not.to.equal(schemaConfig);
+
+      const mappedSchemaTypeMap = toTypeMap(config.types);
+      for (const [typeName, type] of Object.entries(schemaTypeMap)) {
+        if (typeName === 'Query') {
+          expect(mappedSchemaTypeMap[typeName]).not.to.equal(type);
+        } else {
+          expect(mappedSchemaTypeMap[typeName]).to.equal(type);
+        }
+      }
+      return schemaConfigWithDescription;
+    }
+
+    mapSchemaConfig(schema.toConfig(), () => ({
+      [SchemaElementKind.SCHEMA]: schemaMapper,
+    }));
+  });
+});