introduce transformer from latest incremental format to legacy format

src/transform/__tests__/buildTransformationContext-test.ts

@@ -0,0 +1,59 @@
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { invariant } from '../../jsutils/invariant.js';
+
+import { parse } from '../../language/parser.js';
+
+import { GraphQLObjectType } from '../../type/definition.js';
+import { GraphQLString } from '../../type/scalars.js';
+import { GraphQLSchema } from '../../type/schema.js';
+
+import { validateExecutionArgs } from '../../execution/execute.js';
+
+import { buildTransformationContext } from '../buildTransformationContext.js';
+
+const schema = new GraphQLSchema({
+  query: new GraphQLObjectType({
+    name: 'Query',
+    fields: { someField: { type: GraphQLString } },
+  }),
+});
+
+describe('buildTransformationContext', () => {
+  it('should build a transformation context', () => {
+    const validatedExecutionArgs = validateExecutionArgs({
+      schema,
+      document: parse('{ someField }'),
+    });
+
+    invariant('schema' in validatedExecutionArgs);
+
+    const context = buildTransformationContext(
+      validatedExecutionArgs,
+      '__prefix__',
+    );
+
+    expect(context.originalDeferLabels instanceof Map).to.equal(true);
+    expect(context.originalStreamLabels instanceof Map).to.equal(true);
+    expect(context.deferredGroupedFieldSets instanceof Map).to.equal(true);
+    expect(context.streams instanceof Map).to.equal(true);
+    expect(context.prefix).to.equal('__prefix__');
+    expect(context.pendingLabelsByPath instanceof Map).to.equal(true);
+    expect(context.pendingResultsById instanceof Map).to.equal(true);
+    expect(context.mergedResult).to.deep.equal({});
+  });
+
+  it('should handle non-standard directives', () => {
+    const validatedExecutionArgs = validateExecutionArgs({
+      schema,
+      document: parse('{ ... @someDirective { someField } }'),
+    });
+
+    invariant('schema' in validatedExecutionArgs);
+
+    expect(() =>
+      buildTransformationContext(validatedExecutionArgs, '__prefix__'),
+    ).not.to.throw();
+  });
+});