feat: simplify error handling and add test coverage

Author: philippfromme

demo/server.mjs

@@ -63,7 +63,7 @@ app.post('/api/deploy', async (req, res) => {
   } catch (err) {
     console.error('Deployment error:', err);
 
-    res.status(500).json({ error: err.message });
+    res.status(500).json({ success: false, error: err.message });
   }
 });
 
@@ -95,7 +95,7 @@ app.post('/api/startInstance', async (req, res) => {
 
     res.json({ success: true, response });
   } catch (err) {
-    res.status(500).json({ error: err.message });
+    res.status(500).json({ success: false, error: err.message });
   }
 });
 
@@ -117,7 +117,7 @@ app.get('/api/getProcessInstance/:processInstanceKey', async (req, res) => {
 
     res.json({ success: true, response });
   } catch (err) {
-    res.status(500).json({ error: err.message });
+    res.status(500).json({ success: false, error: err.message });
   }
 });
 
@@ -139,7 +139,7 @@ app.get('/api/getProcessInstanceVariables/:processInstanceKey', async (req, res)
 
     res.json({ success: true, response });
   } catch (err) {
-    res.status(500).json({ error: err.message });
+    res.status(500).json({ success: false, error: err.message });
   }
 });
 
@@ -161,7 +161,7 @@ app.get('/api/getProcessInstanceIncident/:processInstanceKey', async (req, res)
 
     res.json({ success: true, response });
   } catch (err) {
-    res.status(500).json({ error: err.message });
+    res.status(500).json({ success: false, error: err.message });
   }
 });
 

lib/TaskExecution.js

@@ -126,92 +126,75 @@ export default class TaskExecution extends EventEmitter {
     /** @type {import('./types').TaskExecutionEvents.Start} */
     this.emit('taskExecution.start');
 
-    const deploymentResponse = await this._api.deploy();
+    const deploymentResult = await this._api.deploy();
 
-    if (!deploymentResponse.success) {
-
-      /** @type {import('./types').TaskExecutionEvents.Error} */
-      this.emit('taskExecution.error', {
-        message: 'Failed to deploy process definition',
-        response: deploymentResponse
-      });
+    if (!deploymentResult.success) {
+      this.emitError('Failed to deploy process definition', deploymentResult.error);
 
       await this.cancelTaskExecution();
 
       return;
     }
 
-    const processId = getProcessId(deploymentResponse.response);
+    const processId = getProcessId(deploymentResult.response);
 
     if (!processId) {
-
-      /** @type {import('./types').TaskExecutionEvents.Error} */
-      this.emit('taskExecution.error', {
-        message: 'Failed to retrieve process ID from deployment response',
-        response: deploymentResponse
-      });
+      this.emitError('Failed to retrieve process ID from deployment response');
 
       await this.cancelTaskExecution();
 
       return;
     }
 
-    this._currentTaskExecution.processDefinitionKey = getProcessDefinitionKey(deploymentResponse.response);
-
-    const startInstanceResponse = await this._api.startInstance(processId, elementId, variables);
+    this._currentTaskExecution.processDefinitionKey = getProcessDefinitionKey(deploymentResult.response);
 
-    if (!startInstanceResponse.success) {
+    const startInstanceResult = await this._api.startInstance(processId, elementId, variables);
 
-      /** @type {import('./types').TaskExecutionEvents.Error} */
-      this.emit('taskExecution.error', {
-        message: 'Failed to start process instance',
-        response: startInstanceResponse
-      });
+    if (!startInstanceResult.success) {
+      this.emitError('Failed to start process instance', startInstanceResult.error);
 
       await this.cancelTaskExecution();
 
       return;
     }
 
-    const { processInstanceKey } = startInstanceResponse.response;
+    const processInstanceKey = getProcessInstanceKey(startInstanceResult.response);
+
+    if (!processInstanceKey) {
+      this.emitError('Failed to retrieve process instance key from start instance response');
+
+      await this.cancelTaskExecution();
+
+      return;
+    }
 
     this._currentTaskExecution.processInstanceKey = processInstanceKey;
 
     const intervalCallback = async () => {
       const getProcessInstanceResult = await this._api.getProcessInstance(processInstanceKey);
 
       if (!getProcessInstanceResult.success) {
-
-        /** @type {import('./types').TaskExecutionEvents.Error} */
-        this.emit('taskExecution.error', {
-          message: 'Failed to get process instance',
-          response: getProcessInstanceResult
-        });
+        this.emitError('Failed to get process instance', getProcessInstanceResult.error);
 
         return;
       }
 
-      const processInstance = getProcessInstance(getProcessInstanceResult.response);
+      const processInstance = getProcessInstance(getProcessInstanceResult.response, processInstanceKey);
 
       if (!processInstance) {
 
         // No process instance found, try again
         return;
       }
 
-      const state = getProcessInstanceState(getProcessInstanceResult.response),
-            hasIncident = hasProcessInstanceIncident(getProcessInstanceResult.response);
+      const state = getProcessInstanceState(getProcessInstanceResult.response, processInstanceKey),
+            hasIncident = hasProcessInstanceIncident(getProcessInstanceResult.response, processInstanceKey);
 
       if (hasIncident) {
         const getProcessInstanceIncidentResult = await this._api.getProcessInstanceIncident(processInstanceKey);
 
         if (!getProcessInstanceIncidentResult.success) {
-
-          /** @type {import('./types').TaskExecutionEvents.Error} */
-          this.emit('taskExecution.error', {
-            message: 'Failed to get process instance incident',
-            response: getProcessInstanceIncidentResult
-          });
+          this.emitError('Failed to get process instance incident', getProcessInstanceIncidentResult.error);
 
           return;
         }
@@ -231,10 +214,7 @@ export default class TaskExecution extends EventEmitter {
         const getProcessInstanceVariablesResult = await this._api.getProcessInstanceVariables(processInstanceKey);
 
         if (!getProcessInstanceVariablesResult.success) {
-          this.emit('taskExecution.error', {
-            message: 'Failed to get process instance variables',
-            response: getProcessInstanceVariablesResult
-          });
+          this.emitError('Failed to get process instance variables', getProcessInstanceVariablesResult.error);
         } else {
           if (this._currentTaskExecution) {
             this._currentTaskExecution.variables = getVariables(getProcessInstanceVariablesResult.response);
@@ -247,16 +227,29 @@ export default class TaskExecution extends EventEmitter {
 
     this._currentTaskExecution.interval = setInterval(intervalCallback, INTERVAL_MS);
   }
+
+  emitError(message, detail) {
+
+    /** @type {import('./types').TaskExecutionEvents.Error} */
+    this.emit('taskExecution.error', {
+      message,
+      detail
+    });
+  }
 }
 
 /**
  * Get the process ID from the deployment response.
  *
- * @param {import('./types').DeploymentResponse} response
+ * @param {import('./types').DeploymentResponse} [response]
  *
  * @returns {string|null} The process ID or null if not found.
  */
 function getProcessId(response) {
+  if (!response) {
+    return null;
+  }
+
   const { processes = [] } = response;
 
   for (const process of processes) {
@@ -271,11 +264,15 @@ function getProcessId(response) {
 /**
  * Get the process definition key from the deployment response.
  *
- * @param {import('./types').DeploymentResponse} response
+ * @param {import('./types').DeploymentResponse} [response]
  *
  * @returns {string|null} The process definition key or null if not found.
  */
 function getProcessDefinitionKey(response) {
+  if (!response) {
+    return null;
+  }
+
   const { processes = [] } = response;
 
   for (const process of processes) {
@@ -287,18 +284,35 @@ function getProcessDefinitionKey(response) {
   return null;
 }
 
-function getProcessInstance(response) {
+/**
+ * Get the process instance key from the response.
+ *
+ * @param {import('./types').StartInstanceResponse} [response]
+ *
+ * @returns {string|null} The process instance key or null if not found.
+ */
+function getProcessInstanceKey(response) {
+  if (!response) {
+    return null;
+  }
+
+  const { processInstanceKey } = response;
+
+  return processInstanceKey || null;
+}
+
+function getProcessInstance(response, processInstanceKey) {
   const { items = [] } = response;
 
   if (!items.length) {
     return null;
   }
 
-  return items[0];
+  return items.find(item => item.processInstanceKey === processInstanceKey) || null;
 }
 
-function getProcessInstanceState(response) {
-  const processInstance = getProcessInstance(response);
+function getProcessInstanceState(response, processInstanceKey) {
+  const processInstance = getProcessInstance(response, processInstanceKey);
 
   if (!processInstance) {
     return null;
@@ -307,8 +321,8 @@ function getProcessInstanceState(response) {
   return processInstance.state;
 }
 
-function hasProcessInstanceIncident(response) {
-  const processInstance = getProcessInstance(response);
+function hasProcessInstanceIncident(response, processInstanceKey) {
+  const processInstance = getProcessInstance(response, processInstanceKey);
 
   if (!processInstance) {
     return false;
@@ -325,7 +339,11 @@ function getVariables(response) {
   for (const item of items) {
     const { name, value } = item;
 
-    variables[name] = JSON.parse(value);
+    try {
+      variables[name] = JSON.parse(value);
+    } catch {
+      variables[name] = value;
+    }
   }
 
   return variables;

lib/components/Output/Output.jsx

@@ -180,7 +180,7 @@ function Error({
         maxCollapsedNumberOfRows={ 100 }
         align="left"
       >
-        { printError(incident) }
+        { printIncident(incident) }
       </CodeSnippet>
     }
     {
@@ -191,17 +191,24 @@ function Error({
         maxCollapsedNumberOfRows={ 100 }
         align="left"
       >
-        { printError(error) }
+        { error.detail || 'No error details available' }
       </CodeSnippet>
     }
   </>;
 }
 
-function printError(error) {
+/**
+ * Print the details of an incident.
+ *
+ * @param {Object} incident
+ *
+ * @returns {string}
+ */
+function printIncident(incident) {
   let text = '';
 
-  Object.keys(error).forEach((key) => {
-    text += `${capitalize(key)}: ${JSON.stringify(error[key], null, 2)}\n`;
+  Object.keys(incident).forEach((key) => {
+    text += `${capitalize(key)}: ${JSON.stringify(incident[key], null, 2)}\n`;
   });
 
   return text;

lib/components/TaskTesting/TaskTesting.js

@@ -155,7 +155,7 @@ export default function TaskTesting({
 
     taskExecutionRef.current.on('taskExecution.start', handleTaskExecutionStart);
 
-    const handleTaskExecutionError = ({ message, response }) => {
+    const handleTaskExecutionError = ({ message, detail }) => {
       setIsTaskExecuting(false);
 
       if (!element || !elementConfigRef.current) {
@@ -166,7 +166,7 @@ export default function TaskTesting({
         success: false,
         error: {
           message,
-          response
+          detail
         }
       });
     };

lib/types.d.ts

@@ -39,29 +39,34 @@ export type DeploymentResponse = DeployResourceResponse;
 
 export type DeploymentResult = {
   success: boolean;
-  response: DeploymentResponse;
+  response?: DeploymentResponse;
+  error?: string;
 }
 
 export type StartInstanceResponse = CreateProcessInstanceResponse;
 
 export type StartInstanceResult = {
   success: boolean;
-  response: StartInstanceResponse;
+  response?: StartInstanceResponse;
+  error?: string;
 }
 
 export type GetProcessInstanceResult = {
   success: boolean;
-  response: SearchProcessInstanceResponse;
+  response?: SearchProcessInstanceResponse;
+  error?: string;
 }
 
 export type GetProcessInstanceVariablesResult = {
   success: boolean;
-  response: SearchVariablesResponse;
+  response?: SearchVariablesResponse;
+  error?: string;
 }
 
 export type GetProcessInstanceIncidentResult = {
   success: boolean;
-  response: SearchIncidentsResponse;
+  response?: SearchIncidentsResponse;
+  error?: string;
 }
 
 export type TaskExecutionApi = {