Add a new parameter to HttpStep that specifies the next step when HTTP request responds with a non-OK code (#201)

Author: RayDNoper

samples/steps/http-get.md

@@ -141,4 +141,26 @@ return_value:
   return: ${the_message.request}
 ```
 
+### HTTP Error handling
+
+It is possible to specify the DSL step to follow when GET request gets a
+non-OK response. For that the `error` field can be used
+```
+get_message:
+  call: http.get
+  args:
+    url: http://localhost:8080/guards/fail/mock-response #step that always gives 403
+    query:
+      var: "value"
+  result: the_message
+  error: error_step
+
+return_value:
+  return: ${the_message.request}
+  
+error_step:
+  return: "Request failed"
+  status: 500  
+```
+
 [Back to Guide](../GUIDE.md#Writing-DSL-files)

samples/steps/http-post.md

@@ -75,4 +75,26 @@ return_value:
   return: ${the_message.response}
 ```
 
+### HTTP Error handling
+
+It is possible to specify the DSL step to follow when POST request gets a
+non-OK response. For that the `error` field can be used
+```
+post_step:
+  call: http.post
+  args:
+    url: http://localhost:8080/nonexistant
+    contentType: plaintext
+    plaintext: 
+        "byrokratt"
+  result: the_message
+
+return_value:
+  return: ${the_message.request}
+  
+error_step:
+  return: "Request failed"
+  status: 500  
+```
+
 [Back to Guide](../GUIDE.md#Writing-DSL-files)

src/main/java/ee/buerokratt/ruuter/domain/steps/http/HttpStep.java

@@ -37,14 +37,21 @@ public abstract class HttpStep extends DslStep {
     protected DefaultHttpDsl localHttpExceptionDsl;
     protected Logging logging;
 
+    @JsonAlias("error")
+    protected String onErrorStep;
+
     @Override
     protected void executeStepAction(DslInstance di) {
         args.checkUrl(di);
         ResponseEntity<Object> response = getRequestResponse(di);
         di.getContext().put(resultName, new HttpStepResult(args, response, MDC.get("spanId")));
 
         if (!isAllowedHttpStatusCode(di, response.getStatusCodeValue())) {
-            throw new IllegalArgumentException();
+            if (getOnErrorStep() != null) {
+                setNextStepName(getOnErrorStep());
+            }
+            else
+                throw new IllegalArgumentException();
         }
     }