Merge pull request #199 from marcusholl/pr/supportAssertOfLogMessageInCaseOfFailures

Support check for log messages in case of exceptions in code under test

test/groovy/util/JenkinsLoggingRule.groovy

@@ -1,20 +1,33 @@
 package util
 
 import com.lesfurets.jenkins.unit.BasePipelineTest
+
+import org.junit.Assert
 import org.junit.rules.TestRule
 import org.junit.runner.Description
 import org.junit.runners.model.Statement
 
+import static org.hamcrest.Matchers.containsString
+import static org.junit.Assert.assertThat;
+
+import org.hamcrest.Matchers
+
 class JenkinsLoggingRule implements TestRule {
 
     final BasePipelineTest testInstance
 
+    def expected = []
+
     String log = ""
 
     JenkinsLoggingRule(BasePipelineTest testInstance) {
         this.testInstance = testInstance
     }
 
+    public void expect(String substring) {
+        expected.add(substring)
+    }
+
     @Override
     Statement apply(Statement base, Description description) {
         return statement(base)
@@ -30,7 +43,30 @@ class JenkinsLoggingRule implements TestRule {
                         log += "$echoInput \n"
                 })
 
-                base.evaluate()
+                Throwable caught
+
+                try {
+                    base.evaluate()
+                } catch(Throwable thr) {
+                    caught = thr
+                } finally {
+                    if(caught instanceof AssertionError) {
+                        // Be polite, give other rules the advantage.
+                        // We expect other rules located closer to the test case
+                        // to throw an AssertionError in case of a violation.
+                        throw caught
+                    }
+
+                    expected.each { substring -> assertThat("Substring '${substring} not contained in log.'",
+                                                            log,
+                                                            containsString(substring)) }
+
+                    if(caught != null) {
+                        // do not swallow, so that other rules located farer away
+                        // to the test case can react
+                        throw caught
+                    }
+                }
             }
         }
     }