diff --git a/src/index.ts b/src/index.ts
index c6f2c2e..fed5312 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,11 +1,9 @@
 import { createLogger } from 'bunyan';
-import { applyDiff, diff } from 'deep-diff';
-import { cloneDeep } from 'lodash';
 import { Options, usage } from 'yargs';
 
 import { loadConfig } from 'src/config';
 import { YamlParser } from 'src/parser/YamlParser';
-import { loadRules, resolveRules } from 'src/rule';
+import { loadRules, resolveRules, visitRules } from 'src/rule';
 import { loadSource, writeSource } from 'src/source';
 import { VERSION_INFO } from 'src/version';
 import { VisitorContext } from 'src/visitor/context';
@@ -21,7 +19,7 @@ const RULE_OPTION: Options = {
   type: 'array',
 };
 
-const MAIN_ARGS = usage(`Usage: salty-dog <mode> [options]`)
+const MAIN_ARGS = usage(`Usage: salty-dog [-m mode] [options]`)
   .option(CONFIG_ARGS_NAME, {
     default: `.${VERSION_INFO.app.name}.yml`,
     group: 'Config:',
@@ -95,6 +93,7 @@ export async function main(argv: Array<string>): Promise<number> {
   // check mode
   if (!MODES.includes(args.mode)) {
     logger.error({ mode: args.mode }, 'unsupported mode');
+    return STATUS_ERROR;
   }
 
   // const schema = new Schema();
@@ -123,32 +122,7 @@ export async function main(argv: Array<string>): Promise<number> {
   }
 
   for (const data of docs) {
-    for (const rule of activeRules) {
-      const items = await rule.pick(ctx, data);
-      for (const item of items) {
-        const itemCopy = cloneDeep(item);
-        const itemResult = await rule.visit(ctx, itemCopy);
-
-        if (itemResult.errors.length > 0) {
-          logger.warn({ count: itemResult.errors.length, rule }, 'rule failed');
-
-          ctx.mergeResult(itemResult);
-        } else {
-          const itemDiff = diff(item, itemCopy);
-          if (Array.isArray(itemDiff) && itemDiff.length > 0) {
-            logger.info({
-              diff: itemDiff,
-              item,
-              rule: rule.name,
-            }, 'rule passed with modifications');
-
-            applyDiff(item, itemCopy);
-          } else {
-            logger.info({ rule: rule.name }, 'rule passed');
-          }
-        }
-      }
-    }
+    await visitRules(ctx, activeRules, data);
   }
 
   if (ctx.errors.length > 0) {
diff --git a/src/rule.ts b/src/rule.ts
index 836707d..7d312c5 100644
--- a/src/rule.ts
+++ b/src/rule.ts
@@ -1,3 +1,4 @@
+import { applyDiff, diff } from 'deep-diff';
 import { JSONPath } from 'jsonpath-plus';
 import { cloneDeep, intersection, isNil } from 'lodash';
 import { LogLevel } from 'noicejs';
@@ -114,9 +115,39 @@ export async function resolveRules(rules: Array<Rule>, selector: RuleSelector):
   return Array.from(activeRules);
 }
 
+export async function visitRules(ctx: VisitorContext, rules: Array<Rule>, data: any): Promise<VisitorContext> {
+  for (const rule of rules) {
+    const items = await rule.pick(ctx, data);
+    for (const item of items) {
+      const itemCopy = cloneDeep(item);
+      const itemResult = await rule.visit(ctx, itemCopy);
+
+      if (itemResult.errors.length > 0) {
+        ctx.logger.warn({ count: itemResult.errors.length, rule }, 'rule failed');
+        ctx.mergeResult(itemResult);
+      } else {
+        const itemDiff = diff(item, itemCopy);
+        if (Array.isArray(itemDiff) && itemDiff.length > 0) {
+          ctx.logger.info({
+            diff: itemDiff,
+            item,
+            rule: rule.name,
+          }, 'rule passed with modifications');
+
+          applyDiff(item, itemCopy);
+        } else {
+          ctx.logger.info({ rule: rule.name }, 'rule passed');
+        }
+      }
+    }
+  }
+
+  return ctx;
+}
+
 export interface RuleResult extends VisitorResult {
   rule: Rule;
-} 
+}
 
 export class Rule implements RuleData, Visitor<RuleResult> {
   public readonly check: any;
@@ -156,7 +187,7 @@ export class Rule implements RuleData, Visitor<RuleResult> {
   }
 
   public async visit(ctx: VisitorContext, node: any): Promise<RuleResult> {
-    ctx.logger.debug({ item: node, rule: this}, 'visiting node');
+    ctx.logger.debug({ item: node, rule: this }, 'visiting node');
 
     const check = ctx.ajv.compile(this.check);
     const filter = this.compileFilter(ctx);