ScriptShellRunner should have correct run detection

- Fix run detection so that @ has to be first character in a first
  argument and it also has additional content, like @path-to-file.
- This fixes issue where `--arg @` would blow up as an normal
  option argument.
- Backport #996
- Fixes #1003

spring-shell-core/src/main/java/org/springframework/shell/jline/ScriptShellRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2022 the original author or authors.
+ * Copyright 2018-2024 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.
@@ -28,7 +28,6 @@ import org.springframework.boot.ApplicationArguments;
 import org.springframework.core.annotation.Order;
 import org.springframework.shell.Shell;
 import org.springframework.shell.ShellRunner;
-import org.springframework.util.ObjectUtils;
 
 /**
  * A {@link ShellRunner} that looks for process arguments that start with {@literal @}, which are then interpreted as
@@ -61,11 +60,11 @@ public class ScriptShellRunner implements ShellRunner {
 
 	@Override
 	public boolean canRun(ApplicationArguments args) {
-		List<File> scriptsToRun = args.getNonOptionArgs().stream()
-				.filter(s -> s.startsWith("@"))
-				.map(s -> new File(s.substring(1)))
-				.collect(Collectors.toList());
-		return !ObjectUtils.isEmpty(scriptsToRun);
+		String[] sourceArgs = args.getSourceArgs();
+		if (sourceArgs.length > 0 && sourceArgs[0].startsWith("@") && sourceArgs[0].length() > 1) {
+			return true;
+		}
+		return false;
 	}
 
 	//tag::documentation[]

spring-shell-core/src/test/java/org/springframework/shell/jline/ScriptShellRunnerTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2024 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.shell.jline;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.ApplicationArguments;
+import org.springframework.boot.DefaultApplicationArguments;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ScriptShellRunnerTests {
+
+	private ScriptShellRunner runner = new ScriptShellRunner(null, null);
+
+	@Test
+	void shouldNotRunWhenNoArgs() {
+		assertThat(runner.canRun(of())).isFalse();
+	}
+
+	@Test
+	void shouldNotRunWhenInOptionValue() {
+		assertThat(runner.canRun(of("--foo", "@"))).isFalse();
+	}
+
+	@Test
+	void shouldNotRunWhenJustFirstArgWithoutFile() {
+		assertThat(runner.canRun(of("@"))).isFalse();
+	}
+
+	@Test
+	void shouldRunWhenFirstArgHavingFile() {
+		assertThat(runner.canRun(of("@file"))).isTrue();
+	}
+
+	private static ApplicationArguments of(String... args) {
+		return new DefaultApplicationArguments(args);
+	}
+}