Reproduce

Steps

Configure redis

In WSL/Linux:

spring:
  data:
    redis:
      host: localhost
      port: 6379

Run test

mvn test -f "./pom.xml"

Results

Settings.json

{
    "java.compile.nullAnalysis.mode": "automatic",
    "java.configuration.updateBuildConfiguration": "automatic"
}

SourceCode

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>com.foo.deadcode</groupId>
    <artifactId>deadcode</artifactId>
    <version>0.0.0</version>
    <packaging>jar</packaging>
    <properties>
        <maven.compiler.source>21</maven.compiler.source>
        <maven.compiler.target>21</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <argLine></argLine>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>3.5.3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>io.valkey</groupId>
            <artifactId>valkey-java</artifactId>
            <version>5.4.0</version>
        </dependency>
        <!-- Or redis-java -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
            <version>3.5.3</version>
        </dependency>

        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-core</artifactId>
            <version>5.18.0</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>3.5.3</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>3.5.3</version>
            </plugin>
        </plugins>
    </build>
</project>

application.yaml

spring:
  data:
    redis:
      host: localhost
      port: 6379

App.java

package com.foo.deadcode;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

IsThisDead.java

package com.foo.deadcode.checker;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.DataAccessException;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.data.redis.core.SessionCallback;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.lang.NonNull;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;

@Component
public class IsThisDead {
    @Autowired
    StringRedisTemplate redisTemplate;

    public List<Object> checkDead() {
        List<Object> result = redisTemplate.execute(new SessionCallback<List<Object>>() {
            @Override
            @Nullable
            public <K, V> List<Object> execute(@NonNull RedisOperations<K, V> op)
                    throws DataAccessException, ClassCastException {
                return null;
            }
        });// }, redisTemplate.getValueSerializer());
        if (result == null) {
            System.out.println("If print, this is not dead");
        }
        return result;
    }
}

TestDead.java

package com.foo.deadcode;

import static org.junit.jupiter.api.Assertions.assertNull;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.foo.deadcode.checker.IsThisDead;

@SpringBootTest
public class TestDead {
    @Autowired
    IsThisDead checker;

    @Test
    void checkDead() {
        assertNull(checker.checkDead());
    }
}