Added --print-dependencies to data generator

refs https://github.com/TryGhost/DevOps/issues/119

- this allows you to debug the dependency chain to understand why a
  particular table is being generated

ghost/core/core/cli/generate-data.js

@@ -10,6 +10,7 @@ module.exports = class DataGeneratorCommand extends Command {
         this.argument('--clear-database', {type: 'boolean', defaultValue: false, desc: 'Clear all entries in the database before importing'});
         this.argument('--tables', {type: 'string', desc: 'Only import the specified list of tables, where quantities can be specified by appending a colon followed by the quantity for each table. Example: --tables=members:1000,posts,tags,members_login_events'});
         this.argument('--with-default', {type: 'boolean', defaultValue: false, desc: 'Include default tables as well as those specified (simply override quantities)'});
+        this.argument('--print-dependencies', {type: 'boolean', defaultValue: false, desc: 'Prints the dependency tree for the data generator and exits'});
     }
 
     initializeContext(context) {
@@ -51,7 +52,8 @@ module.exports = class DataGeneratorCommand extends Command {
             baseUrl: config.getSiteUrl(),
             clearDatabase: argv['clear-database'],
             tables,
-            withDefault: argv['with-default']
+            withDefault: argv['with-default'],
+            printDependencies: argv['print-dependencies']
         });
         try {
             await dataGenerator.importData();

ghost/data-generator/lib/DataGenerator.js

@@ -18,6 +18,7 @@ class DataGenerator {
         baseDataPack = '',
         baseUrl,
         logger,
+        printDependencies,
         withDefault
     }) {
         this.knex = knex;
@@ -28,6 +29,7 @@ class DataGenerator {
         this.baseUrl = baseUrl;
         this.logger = logger;
         this.withDefault = withDefault;
+        this.printDependencies = printDependencies;
     }
 
     sortTableList() {
@@ -158,6 +160,14 @@ class DataGenerator {
 
         this.sortTableList();
 
+        if (this.printDependencies) {
+            this.logger.info('Table dependencies:');
+            for (const table of this.tableList) {
+                this.logger.info(`\t${table.name}: ${table.dependencies.join(', ')}`);
+            }
+            process.exit(0);
+        }
+
         if (this.willClearData) {
             await this.clearData(transaction);
         }