[MINVOKER-273] Environment variable with empty value

pom.xml

@@ -359,7 +359,7 @@ under the License.
             <plugin>
               <groupId>org.apache.maven.plugins</groupId>
               <artifactId>maven-invoker-plugin</artifactId>
-              <version>3.2.1</version>
+              <version>3.2.2</version>
               <configuration>
                 <cloneProjectsTo>${project.build.directory}/it</cloneProjectsTo>
                 <preBuildHookScript>setup</preBuildHookScript>

src/it/invocation-environmentvariable/invoker.properties

@@ -0,0 +1,19 @@
+# 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
+#
+#   http://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.
+
+invoker.environmentVariables.MINVOKER273_PROPERTIES1 = minvoker273_properties1
+invoker.environmentVariables.MINVOKER273_PROPERTIES2 = minvoker273_properties2

src/it/invocation-environmentvariable/pom.xml

@@ -49,6 +49,8 @@ under the License.
           <environmentVariables>
             <MINVOKER145>foobar</MINVOKER145>
             <MINVOKER255_POM>minvoker255_pom</MINVOKER255_POM>
+            <MINVOKER273_PROPERTIES1/>
+            <MINVOKER273_PROPERTIES3/>
           </environmentVariables>
         </configuration>
         <executions>

src/it/invocation-environmentvariable/src/it/minvoker-273/pom.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!--
+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
+
+  http://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.
+-->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.apache.maven.plugins.invoker.its</groupId>
+  <artifactId>minvoker-273</artifactId>
+  <version>0.1-SNAPSHOT</version>
+  <packaging>pom</packaging>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-help-plugin</artifactId>
+        <version>3.2.0</version>
+        <executions>
+          <execution>
+            <phase>validate</phase>
+            <goals>
+              <goal>system</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/it/invocation-environmentvariable/verify.groovy

@@ -16,6 +16,18 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-def buildLog = new File( basedir, 'build.log' )
-assert buildLog.text.contains('[INFO] BUILD SUCCESS')
+
+def buildLog = new File( basedir, 'build.log' ).text
+assert buildLog.contains('[INFO] BUILD SUCCESS')
+
+def buildLod273 = new File( basedir, 'src/it/minvoker-273/build.log' ).text
+
+// MINVOKER273_PROPERTIES1 is present in system environment and should be removed
+assert !buildLod273.contains('MINVOKER273_PROPERTIES1')
+
+// MINVOKER273_PROPERTIES2 is present in system environment and should be present in invocation
+assert buildLod273.contains('MINVOKER273_PROPERTIES2=minvoker273_properties2')
+
+// MINVOKER273_PROPERTIES3 is not present in system environment and should not be present in invocation
+assert !buildLod273.contains('MINVOKER273_PROPERTIES3')