Select specific CLI distribution in CLI's integration tests

Previously, CommandLineInvoker would use the first -bin.zip file found
in build/distributions. If this directory contained multiple zips from
building different versions of Spring Boot, this could result in the
tests being run against the wrong version of the CLI.

This commit updates CommandLineInvoker look for a specific zip in
build/distributions, using the version from gradle.properties to
identify it.

Closes gh-25179

spring-boot-project/spring-boot-cli/src/intTest/java/org/springframework/boot/cli/infrastructure/CommandLineInvoker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -83,8 +83,8 @@ public final class CommandLineInvoker {
 	private File findLaunchScript() throws IOException {
 		File unpacked = new File(this.temp, "unpacked-cli");
 		if (!unpacked.isDirectory()) {
-			File zip = new File(new BuildOutput(getClass()).getRootLocation(), "distributions")
-					.listFiles((pathname) -> pathname.getName().endsWith("-bin.zip"))[0];
+			File zip = new File(new BuildOutput(getClass()).getRootLocation(),
+					"distributions/spring-boot-cli-" + Versions.getBootVersion() + "-bin.zip");
 			try (ZipInputStream input = new ZipInputStream(new FileInputStream(zip))) {
 				ZipEntry entry;
 				while ((entry = input.getNextEntry()) != null) {

spring-boot-project/spring-boot-cli/src/intTest/java/org/springframework/boot/cli/infrastructure/Versions.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2021 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
+ *
+ *      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.
+ */
+
+package org.springframework.boot.cli.infrastructure;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Properties;
+
+/**
+ * Provides access to the current Boot version by referring to {@code gradle.properties}.
+ *
+ * @author Andy Wilkinson
+ */
+final class Versions {
+
+	private Versions() {
+	}
+
+	static String getBootVersion() {
+		Properties gradleProperties = new Properties();
+		try (FileInputStream input = new FileInputStream("../../gradle.properties")) {
+			gradleProperties.load(input);
+			return gradleProperties.getProperty("version");
+		}
+		catch (IOException ex) {
+			throw new RuntimeException(ex);
+		}
+	}
+
+}