How to use no_unused_stubs_reported_on_failure method of org.mockitousage.junitrule.StubbingWarningsJUnitRuleTest class

You seem to be after contradictory goals. On the one hand, you're trying to avoid writing data to disk, which isn't a bad goal in tests. On the other, you're trying to test your I/O-handling class, which means you'll be working with system utilities that assume that your File will work with native calls. As such, here's my guidance:

• Don't try to mock a File. Just don't. Too many native things depend on it.
• If you can, split your I/O-handling code into the half that opens a File and turns it into a Reader, and the half that parses HTML out of the Reader.
• At that point, you don't need a mock at all--just construct a StringReader to simulate the data source.
• While that handles your unit tests pretty well, you may also want to write an integration test that uses a temporary file and ensure that it reads right. (Thanks Brice for adding that tip!)

Don't be afraid to refactor your class to make testing easier, as here:

class YourClass {
  public int method(File file) {
    // do everything here, which is why it requires a mock
  }   
}   

class YourRefactoredClass {
  public int method(File file) {
    return methodForTest(file.getName(), file.isFile(),
        file.isAbsolute(), new FileReader(file));
  }   

  /** For testing only. */
  int methodForTest(
      String name, boolean isFile, boolean isAbsolute, Reader fileContents) {
    // actually do the calculation here
  }   
}   

class YourTest {
  @Test public int methodShouldParseBadHtml() {
    YourRefactoredClass yrc = new YourRefactoredClass();
    assertEquals(42, yrc.methodForTest(
        "bad.html", true, false, new StringReader(badHTMLText));
  }   
}   

At this point the logic in method is so straightforward it's not worth testing, and the logic in methodForTest is so easy to access that you can test it heavily.

You can mock the template but it's better to mock the interface.

    Sender sender = new Sender();
    KafkaOperations template = mock(KafkaOperations.class);
    SettableListenableFuture<SendResult<String, String>> future = new SettableListenableFuture<>();
    when(template.send(anyString(), any(Message.class))).thenReturn(future);
    sender.setTemplate(template);
    sender.send(...);

    future.set(new SendResult<>(...));

    ...or...

    future.setException(...

The solution here is to use a customized answer. Two code samples: the first is the test classes used, the second is the test.

First, the test classes:

private interface Foo
{
    void bar(final List<String> list);
}

private static final class X
{
    private final Foo foo;

    X(final Foo foo)
    {
        this.foo = foo;
    }

    void invokeBar()
    {
        // Note: using Guava's Lists here
        final List<String> list = Lists.newArrayList("a", "b", "c");
        foo.bar(list);
        list.clear();
    }
}

On to the test:

@Test
@SuppressWarnings("unchecked")
public void fooBarIsInvoked()
{
    final Foo foo = mock(Foo.class);
    final X x = new X(foo);

    // This is to capture the arguments with which foo is invoked
    // FINAL IS NECESSARY: non final method variables cannot serve
    // in inner anonymous classes
    final List<String> captured = new ArrayList<String>();

    // Tell that when foo.bar() is invoked with any list, we want to swallow its
    // list elements into the "captured" list
    doAnswer(new Answer()
    {
        @Override
        public Object answer(final InvocationOnMock invocation)
            throws Throwable
        {
            final List<String> list
                = (List<String>) invocation.getArguments()[0];
            captured.addAll(list);
            return null;
        }
    }).when(foo).bar(anyList());

    // Invoke...
    x.invokeBar();

    // Test invocation...
    verify(foo).bar(anyList());

    // Test arguments: works!
    assertEquals(captured, Arrays.asList("a", "b", "c"));
}

Of course, being able to write such a test requires that you are able to inject into your "outer object" sufficient state so that the test is meaningful... Here it is relatively easy.

OK, this is a bad thing to be doing. Don't mock a list; instead, mock the individual objects inside the list. See Mockito: mocking an arraylist that will be looped in a for loop for how to do this.

Also, why are you using PowerMock? You don't seem to be doing anything that requires PowerMock.

But the real cause of your problem is that you are using when on two different objects, before you complete the stubbing. When you call when, and provide the method call that you are trying to stub, then the very next thing you do in either Mockito OR PowerMock is to specify what happens when that method is called - that is, to do the thenReturn part. Each call to when must be followed by one and only one call to thenReturn, before you do any more calls to when. You made two calls to when without calling thenReturn - that's your error.

I don't quite follow what problem you're having using Mockito. Assuming you create a mock of the interface that contains your myMethod() method, you can then verify only the parameters to the method that you are interested in. For example (assuming the interface is called MyInterface and using JUnit 4):

@Test
public void test() {
    MyInterface myInterface = mock(MyInterface.class);
    FooBar expectedFooBar = new FooBar();        

    // other testing stuff

    verify(myInterface).myMethod(any(), any(), eq(expectedFooBar), any(), ...);
}

You'll need to do a static import on the Mockito methods for this to work. The any() matcher doesn't care what value has been passed when verifying.

You can't avoid passing something for every argument in your method (even if it's only NULL).

I don't know of other benefits offhand, but I want to address 2 of your sub-questions (and this is way too long for a comment):

allow mocking without dependency injection - this one isn't clear to me. Can you elaborate?

I think this came from the Motivation wiki page where they describe a way of refactoring code to not invoke static methods to make it testable. For a concrete example of what I think they're getting at, let's say you have this code and you want to test the method mocking the behaviour of the static method, without using powermock:

public class MyClass {
     public void doGetString() {
         ...
         OtherClass.getString(); //It's complex and scary and needs mocking!
         ...
     }
}

One solution, would be to pull the static invocation into its own object, then inject an object that can be mocked come test time. For example, without using other frameworks, this could look like:

public class MyClass {
     public static class StringGetter {
         public getString() {
             return OtherClass.getString();                 
         }
     }

     private final StringGetter getter;

     //Existing Constructor
     public MyClass() {
         this(new StringGetter());
     }

     //DI Constructor
     MyClass(StringGetter getter) {
         this.getter = getter;
     }

     public void doGetString() {
         ...
         getter.getString();
         ...
     }
}

I've seperated the behaviour of my method from the behaviour of the static invocation, and can use the DI constructor to inject mocks easily at test time. Of course with powermock I could just mock the static method in place, and run with it.

And do I need to sacrifice something when using PowerMock?

Physically no, but I'd say philosophically yes :). The below are my opinions, and I try to give good reasons behind them, but of course they are opinions so take them with a grain of salt:

The potentially scary thing that is happening with PowerMock is that in order to accomplish the feats of mocking private and static methods, they are using a custom class loader (which shouldn't be present at runtime in production) and changing the bytecode of your classes. Arguably, this should not matter with the vast majority of classes most of the time, but if you think about it, if the bytecode has changed, and certain side effects are no longer present, you're effectively testing different Classes albiet based upon your existing Classes. Yes this is a very academic argument.

You can somewhat mitigate this first argument by having good comprehensive integration and higher level tests that don't use PowerMock. In this way you can be more confident in the behaviours of your objects even if your unit tests are using PowerMock.

The other argument I have against PowerMock, is that it could almost too easily become a crutch. I agree that PowerMock can help with testing code that uses legacy code and other code that you do not have control over. However I would argue that when you have control over the classes that you need to mock, you should avoid its use. If you write a class with a private method or static method that you need to explicitly mock in order to test other methods, my gut instinct would say that this method may be doing too much and should be refactored and broken up. Having PowerMock already available in a project, you may be tempted to just mock it and move on, which would mitigate the pain that should encourage you to refactor the same. Yes there are sometimes due to various technical and non-technical constraints this is not possible, but it's good to solve pain points instead of avoid them :)

This is a classic case of testing showing up a potential flaw in design. You cannot mock JodaTime because you have a hard-wired dependency to these classes in your class-under-test.

Have a look at the SOLID principles to understand why this could be a problem (especially in this case the Dependency Inversion Principle). If you injected JodaTime somewhere as a dependency, then in your unit test you would be able to replace a real instace of it with a mock, stub or spy as appropriate.

However: JodaTime is something that is highly unlikely to be injected with anything else in the production environment, no matter how long it is live for. Instead, in this case you would probably be better served with the Composed Method Design Pattern. Here, you would extract whatever calculation/algorithm you use to generate the printjobName to another method (I can't see how you do it here because your code snippet never assigns a value to that variable). Then you can spy (partial mock) your class under test to only mock that method and return a fixed value, regardless of the real date time that JodaTime is delivering, for instance:

public class PrintProcessor {
    ...
    public String getPrintJobName(Shipper shipper) {
        String printJobName = null;
        String timeHash = this.getTimeHash();
        if (this.isBeforeFourPM()) {
            switch(shipper) {
                printJobName = // Do something with timeHash to generate name
            }
        } else {
            ...
        }
        return printJobName;
    }

    public boolean isBeforeFourPM() {
        return (jodaTime.getCurrentDateTimeEST().isBefore(jodaTime.getFourPM_EST()) ||
            jodaTime.getCurrentDateTimeEST().isAfter(jodaTime.getSevenPM_EST()));
    }

    public String getTimeHash() {
        ... // Do something to hash the time value in to a String
    }
}

Now you can write in your test:

@Test
public void testGetPrintJobNameBeforeFourPM() {
    PrintProcessor concretePrintProcessor = new PrintProcessor();
    PrintProcessor printProcessor = spy(concretePrintProcessor);
    doReturn(true).when(printProcessor).isBeforeFourPM();

    String printJobName = printProcessor.getPrintJobName(Shipper.X);

    assertEquals("XNCRMNCF", printJobName);
}

I have AngularJS 2 + Spring Boot application with Gradle. I use typescript (.ts file) and npm (node js package manager). So I'm running npm install for generate node_modules and npm run tsc for translating typescript to javascript. I still use some of webjars though, basically dependencies are gathered by npm task during build time and wired by systemjs.config.js file

Below is my folder structure

/src/main/java
/src/main/resources
                   /app           - .ts files and .js translated from .ts
                   /css
                   /js            - systemjs.config.js
                   /node_modules  - generated by npm install
                   /typings       - generated by npm install
                   package.json
                   tsconfig.json
                   typings.json
/src/main/webapp/WEB-INF/jsp      - .jsp files

This is my build.gradle file and add two custom tasks (npmInstall and npmRunTsc) to run npm tasks

build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.3.5.RELEASE")
        classpath("org.flywaydb:flyway-gradle-plugin:3.2.1")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'spring-boot'
apply plugin: 'war'

war {
    baseName = 'my-angular-app'
    version =  '1.0'
    manifest {
        attributes 'Main-Class': 'com.my.Application'
    }
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenLocal()
    mavenCentral()
}

task npmInstall(type:Exec) {
    workingDir 'src/main/resources'
    commandLine 'npm', 'install'
    standardOutput = new ByteArrayOutputStream()
    ext.output = {
        return standardOutput.toString()
    }
}

task npmRunTsc(type:Exec) {
    workingDir 'src/main/resources'
    commandLine 'npm', 'run', 'tsc'
    standardOutput = new ByteArrayOutputStream()
    ext.output = {
        return standardOutput.toString()
    }
}

dependencies {
    // tag::jetty[]
    compile("org.springframework.boot:spring-boot-starter-web")
    compile("org.springframework.boot:spring-boot-starter-tomcat",
            "org.springframework.boot:spring-boot-starter-data-jpa",
            "org.springframework.boot:spring-boot-starter-actuator",
            "org.springframework.boot:spring-boot-starter-security",
            "org.springframework.boot:spring-boot-starter-batch",
            "org.springframework.cloud:spring-cloud-starter-config:1.0.3.RELEASE",
            "org.springframework.cloud:spring-cloud-config-client:1.0.3.RELEASE",
            "com.google.code.gson:gson",
            "commons-lang:commons-lang:2.6",
            "commons-collections:commons-collections",
            "commons-codec:commons-codec:1.10",
            "commons-io:commons-io:2.4",
            "com.h2database:h2",
            "org.hibernate:hibernate-core",
            "org.hibernate:hibernate-entitymanager",
            "org.webjars:datatables:1.10.5",
            "org.webjars:datatables-plugins:ca6ec50",
            "javax.servlet:jstl",
            "org.apache.tomcat.embed:tomcat-embed-jasper",
            "org.quartz-scheduler:quartz:2.2.1",
            "org.jolokia:jolokia-core",
            "org.aspectj:aspectjweaver",
            "org.perf4j:perf4j:0.9.16",
            "commons-jexl:commons-jexl:1.1",
            "cglib:cglib:3.2.1",
            "org.flywaydb:flyway-core",
            )
    providedRuntime("org.springframework.boot:spring-boot-starter-tomcat")
    testCompile("junit:junit",
                "org.springframework:spring-test",
                "org.springframework.boot:spring-boot-starter-test",
                "org.powermock:powermock-api-mockito:1.6.2",
                "org.powermock:powermock-module-junit4:1.6.2",
                )
}

task wrapper(type: Wrapper) {
    gradleVersion = '1.11'
}

When I run the gradle build process I run like below

$ gradle clean npmInstall npmRunTsc test bootRepackage

I can use same systemjs.config.js shown on AngularJS tutorial

systemjs.config.js

(function(global) {
  // map tells the System loader where to look for things
  var map = {
    'app':                        'app', // 'dist',
    'rxjs':                       'node_modules/rxjs',
    'angular2-in-memory-web-api': 'node_modules/angular2-in-memory-web-api',
    '@angular':                   'node_modules/@angular'
  };
  // packages tells the System loader how to load when no filename and/or no extension
  var packages = {
    'app':                        { main: 'main.js',  defaultExtension: 'js' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { defaultExtension: 'js' },
  };
  var packageNames = [
    '@angular/common',
    '@angular/compiler',
    '@angular/core',
    '@angular/http',
    '@angular/platform-browser',
    '@angular/platform-browser-dynamic',
    '@angular/router',
    '@angular/router-deprecated',
    '@angular/testing',
    '@angular/upgrade',
  ];
  // add package entries for angular packages in the form '@angular/common': { main: 'index.js', defaultExtension: 'js' }
  packageNames.forEach(function(pkgName) {
    packages[pkgName] = { main: 'index.js', defaultExtension: 'js' };
  });
  var config = {
    map: map,
    packages: packages
  }
  System.config(config);
})(this);

And on .jsp file I include the systemjs.config.js in head section

<script type="text/javascript" src="node_modules/zone.js/dist/zone.js"></script>
<script type="text/javascript" src="node_modules/reflect-metadata/Reflect.js"></script>
<script type="text/javascript" src="node_modules/systemjs/dist/system.src.js"></script>
<script type="text/javascript" src="js/systemjs.config.js"></script>

For last, to sort out context path I do like below on my Spring WebMvcConfigurerAdapter

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.my.controller")
public class WebConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        if (!registry.hasMappingForPattern("/webjars/**")) {
            registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
        }
        if (!registry.hasMappingForPattern("/images/**")) {
            registry.addResourceHandler("/images/**").addResourceLocations("classpath:/images/");
        }
        if (!registry.hasMappingForPattern("/css/**")) {
            registry.addResourceHandler("/css/**").addResourceLocations("classpath:/css/");
        }
        if (!registry.hasMappingForPattern("/js/**")) {
            registry.addResourceHandler("/js/**").addResourceLocations("classpath:/js/");
        }
        if (!registry.hasMappingForPattern("/app/**")) {
            registry.addResourceHandler("/app/**").addResourceLocations("classpath:/app/");
        }
        if (!registry.hasMappingForPattern("/node_modules/**")) {
            registry.addResourceHandler("/node_modules/**").addResourceLocations("classpath:/node_modules/");
        }
    }

    @Bean
    public InternalResourceViewResolver internalViewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/jsp/");
        viewResolver.setSuffix(".jsp");
        viewResolver.setOrder(1);
        return viewResolver;
    }
}

To see coverage for production code change the pattern to com.cdk.dmg.asset.

You need to Enable coverage in test folders if you want see coverage in tests (this option is disabled on your screenshot and the pattern is set to record data for tests only, hence no results).