0
# MiniCluster Management
1

2
JUnit integration components for managing Flink MiniCluster lifecycle, providing embedded cluster environments for testing Flink applications with support for both JUnit 4 and JUnit 5 frameworks.
3

4
## Capabilities
5

6
### JUnit 5 MiniCluster Extension
7

8
Manages MiniCluster lifecycle as a JUnit 5 extension with automatic startup, shutdown, and configuration management. Supports parameter injection and provides access to test environments and cluster clients.
9

10
```java { .api }
11
@Experimental
12
public class MiniClusterExtension implements BeforeAllCallback, AfterAllCallback, ParameterResolver {
13
    public MiniClusterExtension();
14
    public MiniClusterExtension(MiniClusterResourceConfiguration configuration);
15
    public MiniClusterExtension(Supplier<MiniClusterResourceConfiguration> configurationSupplier);
16
    
17
    public TestStreamEnvironment getTestStreamEnvironment();
18
    public Configuration getClientConfiguration();
19
    public Integer getNumberSlots();
20
    public boolean isRunning();
21
}
22
```
23

24
#### Usage Example
25

26
```java
27
import org.apache.flink.test.junit5.MiniClusterExtension;
28
import org.apache.flink.test.junit5.InjectClusterClient;
29
import org.apache.flink.client.ClusterClient;
30
import org.junit.jupiter.api.Test;
31
import org.junit.jupiter.api.extension.RegisterExtension;
32

33
public class MyStreamingTest {
34
    
35
    @RegisterExtension
36
    static final MiniClusterExtension MINI_CLUSTER_EXTENSION = 
37
        new MiniClusterExtension();
38
    
39
    @Test
40
    void testWithDefaultCluster() throws Exception {
41
        StreamExecutionEnvironment env = 
42
            MINI_CLUSTER_EXTENSION.getTestStreamEnvironment();
43
        // Test implementation
44
    }
45
    
46
    @Test
47
    void testWithInjectedClient(@InjectClusterClient ClusterClient<?> client) {
48
        // Use injected cluster client
49
    }
50
}
51
```
52

53
### Parameter Injection Annotation
54

55
Annotation for injecting cluster client instances into test method parameters, supporting both ClusterClient and RestClusterClient types.
56

57
```java { .api }
58
@Target(ElementType.PARAMETER)
59
@Retention(RetentionPolicy.RUNTIME)
60
@Experimental
61
public @interface InjectClusterClient {
62
}
63
```
64

65
### JUnit 4 MiniCluster Resource
66

67
JUnit 4 resource that manages MiniCluster lifecycle with client access, providing compatibility for legacy test suites.
68

69
```java { .api }
70
public class MiniClusterWithClientResource extends ExternalResource {
71
    public ClusterClient<?> getClusterClient();
72
    public RestClusterClient<?> getRestClusterClient();
73
    public TestStreamEnvironment getTestStreamEnvironment();
74
}
75
```
76

77
#### Usage Example
78

79
```java
80
import org.apache.flink.test.util.MiniClusterWithClientResource;
81
import org.junit.ClassRule;
82
import org.junit.Test;
83

84
public class MyJUnit4Test {
85
    
86
    @ClassRule
87
    public static MiniClusterWithClientResource miniClusterResource = 
88
        new MiniClusterWithClientResource();
89
    
90
    @Test
91
    public void testStreamingJob() throws Exception {
92
        StreamExecutionEnvironment env = 
93
            miniClusterResource.getTestStreamEnvironment();
94
        // Test implementation
95
    }
96
}
97
```
98

99
### Abstract Test Base Classes
100

101
Base classes providing MiniCluster integration and temporary file management for common testing patterns.
102

103
```java { .api }
104
public abstract class AbstractTestBase {
105
    protected String getTempDirPath(String dirName);
106
    protected String getTempFilePath(String fileName);
107
    protected String createTempFile(String fileName, String contents) throws IOException;
108
    protected File createAndRegisterTempFile(String fileName) throws IOException;
109
}
110

111
public abstract class AbstractTestBaseJUnit4 {
112
    // Same API as AbstractTestBase but for JUnit 4
113
}
114
```
115

116
### Parameterized Test Bases
117

118
Base classes for running multiple test programs with parameter variations and execution mode configurations.
119

120
```java { .api }
121
public abstract class MultipleProgramsTestBase extends AbstractTestBase {
122
    public enum TestExecutionMode {
123
        CLUSTER,
124
        CLUSTER_OBJECT_REUSE
125
    }
126
}
127

128
public abstract class MultipleProgramsTestBaseJUnit4 extends AbstractTestBaseJUnit4 {
129
    // JUnit 4 version of MultipleProgramsTestBase
130
}
131
```
132

133
### Single Program Test Bases
134

135
Base classes for single test programs with object reuse variations and execution result tracking.
136

137
```java { .api }
138
public abstract class JavaProgramTestBase extends AbstractTestBase {
139
    public abstract JobExecutionResult testProgram() throws Exception;
140
    
141
    public void setNumberOfTestRepetitions(int numberOfRepetitions);
142
    public int getParallelism();
143
    public JobExecutionResult getLatestExecutionResult();
144
    public boolean isCollectionExecution();
145
}
146

147
public abstract class JavaProgramTestBaseJUnit4 extends AbstractTestBaseJUnit4 {
148
    // JUnit 4 version of JavaProgramTestBase
149
}
150
```
151

152
## Configuration Types
153

154
### MiniCluster Resource Configuration
155

156
Configuration for MiniCluster setup including parallelism, task manager resources, and cluster settings.
157

158
```java { .api }
159
public class MiniClusterResourceConfiguration {
160
    public int getNumberTaskManagers();
161
    public int getNumberSlotsPerTaskManager();
162
    public Configuration getConfiguration();
163
    // Additional configuration methods
164
}
165
```