Problem: Testing MainController with a GetRequest to "/list"

I´ve found a problem testing that mapping because an exception rises evaluanting the view:


The trace:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#strings.arrayJoin(incident.customFields.keySet(), ', ')" (list:29)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:65)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:155)
at hello.MainControllerTest.testGetList(MainControllerTest.java:115)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#strings.arrayJoin(incident.customFields.keySet(), ', ')" (list:29)
at org.thymeleaf.spring4.expression.SpelVariableExpressionEvaluator.evaluate(SpelVariableExpressionEvaluator.java:161)
at org.thymeleaf.standard.expression.VariableExpression.executeVariable(VariableExpression.java:154)
at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:59)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:103)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:133)
at org.thymeleaf.standard.expression.Expression.execute(Expression.java:120)
at org.thymeleaf.standard.processor.attr.AbstractStandardTextChildModifierAttrProcessor.getText(AbstractStandardTextChildModifierAttrProcessor.java:68)
at org.thymeleaf.processor.attr.AbstractTextChildModifierAttrProcessor.getModifiedChildren(AbstractTextChildModifierAttrProcessor.java:59)
at org.thymeleaf.processor.attr.AbstractChildrenModifierAttrProcessor.processAttribute(AbstractChildrenModifierAttrProcessor.java:59)
at org.thymeleaf.processor.attr.AbstractAttrProcessor.doProcess(AbstractAttrProcessor.java:87)
at org.thymeleaf.processor.AbstractProcessor.process(AbstractProcessor.java:212)
at org.thymeleaf.dom.Node.applyNextProcessor(Node.java:1017)
at org.thymeleaf.dom.Node.processNode(Node.java:972)
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
at org.thymeleaf.dom.Node.processNode(Node.java:990)
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
at org.thymeleaf.dom.Node.processNode(Node.java:990)
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
at org.thymeleaf.dom.Node.processNode(Node.java:990)
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
at org.thymeleaf.dom.Node.processNode(Node.java:990)
at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
at org.thymeleaf.dom.Node.processNode(Node.java:990)
at org.thymeleaf.dom.Document.process(Document.java:93)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1155)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060)
at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011)
at org.thymeleaf.spring4.view.ThymeleafView.renderFragment(ThymeleafView.java:335)
at org.thymeleaf.spring4.view.ThymeleafView.render(ThymeleafView.java:190)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1271)
at org.springframework.test.web.servlet.TestDispatcherServlet.render(TestDispatcherServlet.java:105)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
... 39 more
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1011E: Method call: Attempted to call method keySet() on null context object
at org.springframework.expression.spel.ast.MethodReference.throwIfNotNullSafe(MethodReference.java:144)
at org.springframework.expression.spel.ast.MethodReference.getValueRef(MethodReference.java:73)
at org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:66)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:87)
at org.springframework.expression.spel.ast.MethodReference.getArguments(MethodReference.java:154)
at org.springframework.expression.spel.ast.MethodReference.getValueRef(MethodReference.java:71)
at org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:66)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:87)
at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:120)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:267)
at org.thymeleaf.spring4.expression.SpelVariableExpressionEvaluator.evaluate(SpelVariableExpressionEvaluator.java:139)
... 78 more

Start with MainControllerTest.java around line 115 and the list template at line 29, where the failing expression accesses incident.customFields.keySet(). Run the GET /list test and verify that rendering no longer throws when customFields is null.

Written by the indexing model from the issue text.