Resolves mojohaus#973: NPE if actual version is null for a dependency

versions-common/src/main/java/org/codehaus/mojo/versions/api/AbstractVersionDetails.java

@@ -1,22 +1,18 @@
 package org.codehaus.mojo.versions.api;
 
 /*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
+ * Copyright MojoHaus and Contributors
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
  *
- *     http://www.apache.org/licenses/LICENSE-2.0
+ *    https://www.apache.org/licenses/LICENSE-2.0
  *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
 
 import java.util.*;
@@ -82,11 +78,12 @@ protected ArtifactVersion getHighestLowerBound(ArtifactVersion lowerBoundVersion
      * If the artifact is bound by one or more version ranges, returns the restriction that constitutes
      * the version range containing the selected actual version.
      * If there are no version ranges, returns the provided version.
-     * @param selectedVersion actual version used
+     * @param selectedVersion actual version used, may not be {@code null}
      * @return restriction containing the version range selected by the given version,
      * or {@link Optional#empty()} if there are no ranges
      */
     protected Optional<Restriction> getSelectedRestriction(ArtifactVersion selectedVersion) {
+        assert selectedVersion != null;
         return Optional.ofNullable(getCurrentVersionRange())
                 .map(VersionRange::getRestrictions)
                 .flatMap(r -> r.stream()
@@ -116,7 +113,8 @@ public Restriction restrictionForSelectedSegment(ArtifactVersion lowerBound, Opt
     public Restriction restrictionForUnchangedSegment(
             ArtifactVersion actualVersion, Optional<Segment> unchangedSegment, boolean allowDowngrade)
             throws InvalidSegmentException {
-        Optional<Restriction> selectedRestriction = getSelectedRestriction(actualVersion);
+        Optional<Restriction> selectedRestriction =
+                Optional.ofNullable(actualVersion).flatMap(this::getSelectedRestriction);
         ArtifactVersion selectedRestrictionUpperBound =
                 selectedRestriction.map(Restriction::getUpperBound).orElse(actualVersion);
         ArtifactVersion lowerBound = allowDowngrade

versions-common/src/test/java/org/codehaus/mojo/versions/api/AbstractVersionDetailsTest.java

@@ -30,6 +30,7 @@
 import static org.codehaus.mojo.versions.utils.ArtifactVersionUtils.version;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.fail;
 
 /**
  * Unit tests for {@link AbstractVersionDetails}
@@ -156,4 +157,24 @@ public void testRestrictionForUnchangedSegmentWithTwoNotConnectingRanges4()
                         .containsVersion(version("2.0.0-1")),
                 is(true));
     }
+
+    @Test
+    public void testRestrictionForUnchangedSegmentWithoutVersionInformation()
+            throws InvalidSegmentException, InvalidVersionSpecificationException {
+        instance.setCurrentVersionRange(VersionRange.createFromVersionSpec("[,0]"));
+        assertThat(
+                instance.restrictionForUnchangedSegment(null, empty(), false).containsVersion(version("1.0.0")),
+                is(true));
+    }
+
+    @Test
+    public void testGetSelectedRestrictionForNoVersion()
+            throws InvalidVersionSpecificationException, InvalidSegmentException {
+        instance.setCurrentVersionRange(VersionRange.createFromVersionSpec("[,0]"));
+        try {
+            instance.getSelectedRestriction(null);
+            fail("Expected a NullPointerException to be thrown or assertions are not enabled.");
+        } catch (AssertionError ignored) {
+        }
+    }
 }

versions-maven-plugin/src/test/java/org/codehaus/mojo/versions/DisplayDependencyUpdatesMojoTest.java

@@ -17,9 +17,7 @@
 
 import java.io.File;
 import java.nio.file.Files;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.List;
+import java.util.*;
 
 import org.apache.maven.model.Model;
 import org.apache.maven.plugin.MojoExecutionException;