Create a test case for the BuildActionIterator.

src/test/java/io/jenkins/plugins/echarts/BuildActionIteratorTest.java

@@ -0,0 +1,76 @@
+package io.jenkins.plugins.echarts;
+
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+import org.junit.jupiter.api.Test;
+
+import edu.hm.hafner.echarts.BuildResult;
+
+import hudson.model.Run;
+
+import io.jenkins.plugins.util.BuildAction;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+/**
+ * Tests the class {@link BuildActionIterator}.
+ *
+ * @author Ullrich Hafner
+ */
+class BuildActionIteratorTest {
+    @Test
+    void shouldCreateEmptyIterator() {
+        BuildActionIterator<TestAction> iterator = new BuildActionIterator<>(TestAction.class, Optional.empty());
+
+        assertThat(iterator).isExhausted();
+        assertThatExceptionOfType(NoSuchElementException.class).isThrownBy(iterator::next);
+    }
+
+    @Test
+    void shouldReturnResultOfCurrentBuild() {
+        TestAction testAction = mock(TestAction.class);
+        Run<?, ?> baseline = mock(Run.class);
+        when(testAction.getOwner()).thenAnswer(i -> baseline);
+
+        BuildActionIterator<TestAction> iterator = new BuildActionIterator<>(TestAction.class, Optional.of(testAction));
+
+        assertThat(iterator).hasNext();
+        assertThat(iterator.next()).usingRecursiveComparison().ignoringFields("build")
+                .isEqualTo(new BuildResult<>(null, testAction));
+        assertThat(iterator).isExhausted();
+    }
+
+    @Test
+    void shouldReturnResultOfPreviousBuild() {
+        TestAction testAction = mock(TestAction.class);
+        Run<?, ?> baseline = mock(Run.class);
+        when(testAction.getOwner()).thenAnswer(i -> baseline);
+
+        BuildActionIterator<TestAction> iterator = new BuildActionIterator<>(TestAction.class, Optional.of(testAction));
+
+        TestAction previousAction = mock(TestAction.class);
+        Run<?, ?> previousBuild = mock(Run.class);
+        when(previousAction.getOwner()).thenAnswer(i -> previousBuild);
+
+        when(previousBuild.getAction(TestAction.class)).thenReturn(previousAction);
+        when(baseline.getPreviousBuild()).thenAnswer(i -> previousBuild);
+
+        assertThat(iterator).hasNext();
+        assertThat(iterator.next()).usingRecursiveComparison().ignoringFields("build")
+                .isEqualTo(new BuildResult<>(null, testAction));
+
+        assertThat(iterator).hasNext();
+        assertThat(iterator.next()).usingRecursiveComparison().ignoringFields("build")
+                .isEqualTo(new BuildResult<>(null, previousAction));
+    }
+
+    private abstract static class TestAction extends BuildAction<String> {
+        private static final long serialVersionUID = -8129555082892128959L;
+
+        TestAction(final Run<?, ?> owner, final String result) {
+            super(owner, result);
+        }
+    }
+}