BC checker: use readable snapshot output

This output has less information but it should be the right subset to check breaking changes affecting our clients. The good thing is that it's very well readable for us.

kiwicom-source-id: 32abf3c34699c205128c2d6cb7da673aa51e9afa

src/packages/bc-checker/README.md

@@ -0,0 +1,5 @@
+TODO:
+
+- turn this script into bin file (for NPM usage)
+- add "allow BC break option" with BC breaks changelog
+- add README

src/packages/bc-checker/package.json

@@ -4,6 +4,7 @@
   "version": "0.0.0",
   "main": "src/index.js",
   "dependencies": {
-    "@kiwicom/signed-source": "^0"
+    "@kiwicom/signed-source": "^0",
+    "chalk": "^2.4.1"
   }
 }

src/packages/bc-checker/src/index.js

@@ -1,12 +1,7 @@
 // @flow
 /* eslint-disable */
 
-import {
-  findBreakingChanges,
-  buildClientSchema,
-  introspectionQuery,
-  graphql,
-} from 'graphql';
+import { findBreakingChanges, buildSchema, printSchema } from 'graphql';
 import SignedSource from '@kiwicom/signed-source';
 import chalk from 'chalk';
 import path from 'path';
@@ -15,7 +10,10 @@ import fs from 'fs';
 import schema from '../../../Schema.js';
 import paths from '../../../../paths';
 
-const snapshotLocation = path.join(paths.scripts, 'graphql-schema-snapshot.js');
+const snapshotLocation = path.join(
+  paths.scripts,
+  'graphql-schema-snapshot.graphql',
+);
 
 const printChanges = (changes: Object[]) => {
   console.error('');
@@ -26,8 +24,7 @@ const printChanges = (changes: Object[]) => {
 };
 
 (async () => {
-  // $FlowExpectedError: the parameter passed to require() must be a literal string
-  const oldSchema = buildClientSchema(require(snapshotLocation));
+  const oldSchema = buildSchema(fs.readFileSync(snapshotLocation).toString());
   const newSchema = schema;
 
   const changes = findBreakingChanges(oldSchema, newSchema);
@@ -56,15 +53,9 @@ const printChanges = (changes: Object[]) => {
     process.exit(1);
   }
 
-  // non-breaking changes must be committed
-  const meta = await graphql(schema, introspectionQuery);
   const oldSnapshot = fs.readFileSync(snapshotLocation, { encoding: 'utf-8' });
   const newSnapshot = SignedSource.signFile(
-    `// ${SignedSource.getSigningToken()}\n\nmodule.exports = ${JSON.stringify(
-      meta.data,
-      null,
-      2,
-    )}\n`,
+    `# ${SignedSource.getSigningToken()}\n\n${printSchema(schema)}`,
   );
 
   if (!SignedSource.verifySignature(oldSnapshot)) {