Add support for environment variables

See gh-12800

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/EnvVariablesTests.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * 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
+ *
+ * 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.
+ */
+
+package org.springframework.boot.maven;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link EnvVariables}.
+ *
+ * @author Dmytro Nosan
+ */
+public class EnvVariablesTests {
+
+	@Test
+	public void asNull() {
+		Map<String, String> args = new EnvVariables(null).asMap();
+		assertThat(args).hasSize(0);
+	}
+
+
+	@Test
+	public void asArray() {
+		assertThat(new EnvVariables(getTestArgs()).asArray())
+				.contains("key=My Value")
+				.contains("key1= tt ")
+				.contains("key2=")
+				.contains("key3=");
+	}
+
+	@Test
+	public void asMap() {
+		assertThat(new EnvVariables(getTestArgs()).asMap())
+				.containsEntry("key", "My Value")
+				.containsEntry("key1", " tt ")
+				.containsEntry("key2", "")
+				.containsEntry("key3", "");
+	}
+
+
+	private Map<String, String> getTestArgs() {
+		Map<String, String> args = new LinkedHashMap<>();
+		args.put("key", "My Value");
+		//should not be trimmed
+		args.put("key1", " tt ");
+		args.put("key2", "   ");
+		args.put("key3", null);
+		return args;
+	}
+
+
+
+
+}