Add some test demonstrating null pointer problems in the DateRangeParam class

hapi-fhir-base/src/test/java/ca/uhn/fhir/rest/param/DateRangeParamTest.java

@@ -0,0 +1,67 @@
+package ca.uhn.fhir.rest.param;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import ca.uhn.fhir.context.FhirContext;
+import ca.uhn.fhir.rest.api.QualifiedParamList;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.Mockito;
+
+@RunWith(JUnit4.class)
+public class DateRangeParamTest {
+	private FhirContext fhirContext;
+
+	@Before
+	public void initMockContext() {
+		fhirContext = Mockito.mock(FhirContext.class);
+	}
+
+	/** Can happen e.g. when the query parameter for {@code _lastUpdated} is left empty. */
+	@Test
+	public void testParamWithoutPrefixAndWithoutValue() {
+		QualifiedParamList qualifiedParamList = new QualifiedParamList(1);
+		qualifiedParamList.add("");
+
+		List<QualifiedParamList> params = new ArrayList<>(1);
+		params.add(qualifiedParamList);
+		DateRangeParam dateRangeParam = new DateRangeParam();
+		dateRangeParam.setValuesAsQueryTokens(fhirContext, "_lastUpdated", params);
+
+		assertTrue(dateRangeParam.isEmpty());
+	}
+
+	/** Can happen e.g. when the query parameter for {@code _lastUpdated} is given as {@code lt} without any value. */
+	@Test
+	public void testUpperBoundWithPrefixWithoutValue() {
+		QualifiedParamList qualifiedParamList = new QualifiedParamList(1);
+		qualifiedParamList.add("lt");
+
+		List<QualifiedParamList> params = new ArrayList<>(1);
+		params.add(qualifiedParamList);
+		DateRangeParam dateRangeParam = new DateRangeParam();
+		dateRangeParam.setValuesAsQueryTokens(fhirContext, "_lastUpdated", params);
+
+		assertTrue(dateRangeParam.isEmpty());
+	}
+
+	/** Can happen e.g. when the query parameter for {@code _lastUpdated} is given as {@code gt} without any value. */
+	@Test
+	public void testLowerBoundWithPrefixWithoutValue() {
+		QualifiedParamList qualifiedParamList = new QualifiedParamList(1);
+		qualifiedParamList.add("gt");
+
+		List<QualifiedParamList> params = new ArrayList<>(1);
+		params.add(qualifiedParamList);
+		DateRangeParam dateRangeParam = new DateRangeParam();
+		dateRangeParam.setValuesAsQueryTokens(fhirContext, "_lastUpdated", params);
+
+		assertTrue(dateRangeParam.isEmpty());
+	}
+}