LiveFileLoaderTest - not suitable for a build server and breaks the tenets of a good unit test
package com.celestial.mockito.filetodb;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
*
* @author selvy
*/
public class LiveFileLoaderTest
{
// The inital design is described in this test
/*
The weakness should be obvious? The file to be loaded and it's location
I use a shared network drive to run this code from different machines, normally
dev-ing from a PC. When I ran the code on the laptop from a cafe it
immediately failed because the C: on the laptop was completely different
to the PC, so the original file C:/tmp/KeyboardHandler.txt did not exist
THIS IS A GREAT EXAMPLE OF WHY THE UNIT TEST AND CUT SHOULD NOT BE STRONGLY
LINKED TO ANY IO - NETWORK, DB, AND FILE SYSTEM
*/
@Test
public void load_all_of_file_using_inbuilt_Files_type()
{
// arrange
String fileToLoad = "c:/tmp/kipstor-settings.js";
FileLoader cut = new FileLoader(fileToLoad);
int expectedBytesRead = 301;
// act
int bytesRead = cut.loadFile(fileToLoad);
// assert
assertEquals(expectedBytesRead, bytesRead);
}
}
FIleLoader implementation
package com.celestial.mockito.filetodb;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.*;
/**
*
* @author selvy
*/
public class FileLoader
{
private class IntWrapper
{
public int value;
}
String fileToLoad;
List<String> lines = Collections.emptyList();
public FileLoader(String fileToLoad)
{
this.fileToLoad = fileToLoad;
}
int loadFile(String fname)
{
try
{
lines = Files.readAllLines(Paths.get(fname), StandardCharsets.UTF_8);
}
catch (IOException e){}
return calculateFileSize();
}
private int calculateFileSize()
{
IntWrapper result = new IntWrapper();
lines.forEach(line -> {
result.value += line.length();
});
return result.value;
}
}
FileLoaderTest - suitable for a build pipeline and does not break the tenets of unit testing
package com.celestial.mockito.filetodb;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.junit.Test;
import static org.junit.Assert.*;
import org.mockito.MockedStatic;
import org.mockito.Mockito;
/**
*
* @author selvy
*/
public class FileLoaderTest
{
// To use a different type of file system loader, pass a lambda to loadFile()
// as shown here
/*
int bytesRead = cut.loadFile((fname) ->
{
List<String> result = null;
try
{
result = Files.readAllLines(Paths.get(fname), StandardCharsets.UTF_8);
}
catch (IOException e){}
return result;
});
*/
// Redesign the FileLoader so that the machenism to load files up can be
// passed in as a lambda - still titghtly coupled the file system
@Test
public void load_all_of_file_using_inbuilt_Files_type_as_lambda()
{
// arrange
String fileToLoad = "c:/tmp/KeyboardHandler.txt";
FileLoader cut = new FileLoader(fileToLoad);
int expectedBytesRead = 10; //1371;
List<String> pretendFileContent = new ArrayList<>();
pretendFileContent.add("Hello");
pretendFileContent.add("world");
MockedStatic<Files> ff = Mockito.mockStatic(Files.class);
ff.when(() -> Files.readAllLines(Paths.get(fileToLoad), StandardCharsets.UTF_8)).thenReturn(pretendFileContent);
// act
int bytesRead = cut.loadFile((fname) ->
{
List<String> result = null;
try
{
result = Files.readAllLines(Paths.get(fname), StandardCharsets.UTF_8);
}
catch (IOException e){}
return result;
});
// assert
assertEquals(expectedBytesRead, bytesRead);
}
// Redesign has worked so this test uses a stub to simulate a file being
// loaded, it is passed in as lambda - We've decoupled ourselves from the
// filesystem
@Test
public void load_all_of_file_via_stub()
{
// arrange
String fileToLoad = "c:/tmp/KeyboardHandler.txt";
FileLoader cut = new FileLoader(fileToLoad);
int expectedBytesRead = 10;
// act
int bytesRead = cut.loadFile((fname) ->
{
List<String> result = new ArrayList<>();
result.add("Hello");
result.add("world");
return result;
});
// assert
assertEquals(expectedBytesRead, bytesRead);
}
}
FileLoader implementation code - refactored
DBConnector
LiveDBConnectorTest - not suitable for a build server and breaks the tenets of a good unit test
DBConnector - Initial implementation
DBConnectorTest - suitable for a build pipeline and does not break the tenets of unit testing