drop tables afterEach for PG, clean up relation tables too

Author: flovilmart

spec/helper.js

@@ -170,7 +170,9 @@ afterEach(function(done) {
     if (Object.keys(openConnections).length > 0) {
       fail('There were open connections to the server left after the test finished');
     }
-    done();
+    on_db('postgres', () => {
+      TestUtils.destroyAllDataPermanently().then(done, done);
+    }, done);
   };
   Parse.Cloud._removeAllHooks();
   databaseAdapter.getAllClasses()

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -417,9 +417,17 @@ export class PostgresStorageAdapter {
 
   // Delete all data known to this adapter. Used for testing.
   deleteAllClasses() {
-    return this._client.any('SELECT "className" FROM "_SCHEMA"')
+    return this._client.any('SELECT * FROM "_SCHEMA"')
     .then(results => {
-      const classes = ['_SCHEMA','_PushStatus','_Hooks','_GlobalConfig', ...results.map(result => result.className)];
+      let joins = results.reduce((list, schema) => {
+        Object.keys(schema.schema.fields).forEach((field) => {
+          if (schema.schema.fields[field].type === 'Relation') {
+            list.push(`_Join:${field}:${schema.className}`);
+          }
+        })
+        return list;
+      }, []);
+      const classes = ['_SCHEMA','_PushStatus','_Hooks','_GlobalConfig', ...results.map(result => result.className), ...joins];
       return this._client.tx(t=>t.batch(classes.map(className=>t.none('DROP TABLE IF EXISTS $<className:name>', { className }))));
     }, error => {
       if (error.code === PostgresRelationDoesNotExistError) {