From b674f6a3bdf5de358dabd585bcd5e231bdc8f9d9 Mon Sep 17 00:00:00 2001
From: "Philip K. Warren" <pkwarren@gmail.com>
Date: Tue, 26 Oct 2021 20:50:13 -0500
Subject: [PATCH] fix error when using empty agent label

Update AgentDeclaration to only fail if label is null (and not found via
other conditionals) instead of when it is falsy.

Fixes #412
---
 .../unit/declarative/AgentDeclaration.groovy      |  2 +-
 .../declarative/TestDeclarativePipeline.groovy    |  8 ++++++++
 .../jenkinsfiles/AgentEmptyLabel_Jenkinsfile      | 15 +++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 src/test/jenkins/jenkinsfiles/AgentEmptyLabel_Jenkinsfile

diff --git a/src/main/groovy/com/lesfurets/jenkins/unit/declarative/AgentDeclaration.groovy b/src/main/groovy/com/lesfurets/jenkins/unit/declarative/AgentDeclaration.groovy
index 23c6137b..db370f43 100644
--- a/src/main/groovy/com/lesfurets/jenkins/unit/declarative/AgentDeclaration.groovy
+++ b/src/main/groovy/com/lesfurets/jenkins/unit/declarative/AgentDeclaration.groovy
@@ -77,7 +77,7 @@ class AgentDeclaration extends GenericPipelineDeclaration {
     def execute(Object delegate) {
         def agentDesc = null
 
-        if (label) {
+        if (label != null) {
             agentDesc = '[label:' + label.toString() + ']'
         }
         else if (docker) {
diff --git a/src/test/groovy/com/lesfurets/jenkins/unit/declarative/TestDeclarativePipeline.groovy b/src/test/groovy/com/lesfurets/jenkins/unit/declarative/TestDeclarativePipeline.groovy
index 56a5a98a..ecdfeca3 100644
--- a/src/test/groovy/com/lesfurets/jenkins/unit/declarative/TestDeclarativePipeline.groovy
+++ b/src/test/groovy/com/lesfurets/jenkins/unit/declarative/TestDeclarativePipeline.groovy
@@ -647,4 +647,12 @@ class TestDeclarativePipeline extends DeclarativePipelineTest {
         assertCallStack().contains('echo(Deploy to someLabel)')
         assertJobStatusSuccess()
     }
+
+    @Test void should_agent_with_empty_label() throws Exception {
+        runScript('AgentEmptyLabel_Jenkinsfile')
+        printCallStack()
+        assertCallStack().contains('[label:]')
+        assertCallStack().contains('echo(Hello using custom workspace and empty label)')
+        assertJobStatusSuccess()
+    }
 }
diff --git a/src/test/jenkins/jenkinsfiles/AgentEmptyLabel_Jenkinsfile b/src/test/jenkins/jenkinsfiles/AgentEmptyLabel_Jenkinsfile
new file mode 100644
index 00000000..71d1802c
--- /dev/null
+++ b/src/test/jenkins/jenkinsfiles/AgentEmptyLabel_Jenkinsfile
@@ -0,0 +1,15 @@
+pipeline {
+    agent {
+        node {
+            label ''
+            customWorkspace "myworkspace"
+        }
+    }
+    stages {
+        stage('Example Build') {
+            steps {
+                echo "Hello using custom workspace and empty label"
+            }
+        }
+    }
+}