Add test for BuildParameterStrategy class (#435)

* Add test for BuildParameterStrategy class

* remove extra BuildParameterStrategy object

* remove unused Exception from the Test methods

src/test/java/jenkins/advancedqueue/priority/strategy/BuildParameterStrategyTest.java

@@ -0,0 +1,89 @@
+package jenkins.advancedqueue.priority.strategy;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import hudson.model.FreeStyleProject;
+import hudson.model.ParametersAction;
+import hudson.model.Queue;
+import hudson.model.StringParameterValue;
+import java.io.IOException;
+import java.util.Calendar;
+import java.util.Collections;
+import jenkins.advancedqueue.PrioritySorterConfiguration;
+import org.junit.BeforeClass;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.jvnet.hudson.test.JenkinsRule;
+
+public class BuildParameterStrategyTest {
+
+    @ClassRule
+    public static JenkinsRule j = new JenkinsRule();
+
+    private static FreeStyleProject project;
+    private static BuildParameterStrategy strategy;
+
+    @BeforeClass
+    public static void setUp() throws IOException {
+        project = j.createFreeStyleProject();
+        strategy = new BuildParameterStrategy("priority");
+    }
+
+    @Test
+    public void getPriority_returnsPriorityFromParameter() {
+        StringParameterValue param = new StringParameterValue("priority", "5");
+        ParametersAction action = new ParametersAction(param);
+        Queue.Item item = new Queue.WaitingItem(Calendar.getInstance(), project, Collections.singletonList(action));
+
+        int priority = strategy.getPriority(item);
+
+        assertEquals(5, priority);
+    }
+
+    @Test
+    public void getPriority_returnsDefaultPriorityWhenParameterIsMissing() {
+        Queue.Item item = new Queue.WaitingItem(Calendar.getInstance(), project, Collections.emptyList());
+
+        int priority = strategy.getPriority(item);
+
+        assertEquals(PrioritySorterConfiguration.get().getStrategy().getDefaultPriority(), priority);
+    }
+
+    @Test
+    public void getPriority_returnsDefaultPriorityWhenParameterIsNotANumber() {
+        StringParameterValue param = new StringParameterValue("priority", "not-a-number");
+        ParametersAction action = new ParametersAction(param);
+        Queue.Item item = new Queue.WaitingItem(Calendar.getInstance(), project, Collections.singletonList(action));
+
+        int priority = strategy.getPriority(item);
+
+        assertEquals(PrioritySorterConfiguration.get().getStrategy().getDefaultPriority(), priority);
+    }
+
+    @Test
+    public void isApplicable_returnsTrueWhenParameterIsPresentAndValid() {
+        StringParameterValue param = new StringParameterValue("priority", "5");
+        ParametersAction action = new ParametersAction(param);
+        Queue.Item item = new Queue.WaitingItem(Calendar.getInstance(), project, Collections.singletonList(action));
+
+        assertTrue(strategy.isApplicable(item));
+    }
+
+    @Test
+    public void isApplicable_returnsFalseWhenParameterIsMissing() {
+        Queue.Item item = new Queue.WaitingItem(Calendar.getInstance(), project, Collections.emptyList());
+
+        assertFalse(strategy.isApplicable(item));
+    }
+
+    @Test
+    public void isApplicable_returnsFalseWhenParameterIsNotANumber() {
+        StringParameterValue param = new StringParameterValue("priority", "not-a-number");
+        ParametersAction action = new ParametersAction(param);
+        Queue.Item item = new Queue.WaitingItem(Calendar.getInstance(), project, Collections.singletonList(action));
+
+        assertFalse(strategy.isApplicable(item));
+    }
+}