This should fix all issues regarding the "latest" version for all server types

src/main/java/net/knarcraft/minecraftserverlauncher/Main.java

@@ -5,6 +5,7 @@ import net.knarcraft.minecraftserverlauncher.profile.Profile;
 import net.knarcraft.minecraftserverlauncher.server.Server;
 import net.knarcraft.minecraftserverlauncher.userinterface.GUI;
 import net.knarcraft.minecraftserverlauncher.userinterface.ServerConsoles;
+import net.knarcraft.minecraftserverlauncher.utility.CommonFunctions;
 import net.knarcraft.minecraftserverlauncher.utility.Updater;
 
 import java.awt.*;
@@ -80,7 +81,7 @@ public class Main {
                 Server server = collection.getServer();
                 if (server.isEnabled() && server.getProcess() != null) {
                     try {
-                        String readText = server.readFromServer();
+                        String readText = CommonFunctions.readBufferedReader(server.getReader());
                         if (!readText.equals("")) {
                             collection.getServerConsole().output(readText);
                             updatePlayerList(readText, server);

src/main/java/net/knarcraft/minecraftserverlauncher/profile/Profile.java

@@ -29,9 +29,10 @@ import java.util.concurrent.Executors;
  */
 public class Profile implements java.io.Serializable {
     private static final ArrayList<Profile> profiles = new ArrayList<>();
-    private static final String profilesDir = Main.getApplicationWorkDirectory() + File.separator + "files";
-    private static final String profilesFile = Main.getApplicationWorkDirectory() + File.separator + "files" + File.separator + "Profiles.txt";
-    private static final String jarDirectory = Main.getApplicationWorkDirectory() + File.separator + "files" + File.separator + "Jars" + File.separator;
+    private static final String workingDirectory = Main.getApplicationWorkDirectory() + File.separator + "files";
+    private static final String profilesDir = workingDirectory;
+    private static final String profilesFile = workingDirectory + File.separator + "Profiles.txt";
+    private static final String jarDirectory = workingDirectory + File.separator + "Jars" + File.separator;
     private static Profile current;
     private static transient ServerLauncherGUI serverLauncherGui;
     private final ArrayList<Collection> collections;

src/main/java/net/knarcraft/minecraftserverlauncher/server/Server.java

@@ -84,10 +84,24 @@ public class Server implements java.io.Serializable {
         this.playerList = new ArrayList<>();
     }
 
+    /**
+     * Gets the list of available RAM choices allowed
+     *
+     * @return <p>All available RAM choices</p>
+     */
     public static String[] getRamList() {
         return ramList;
     }
 
+    /**
+     * Gets the buffered reader used to read from this server
+     *
+     * @return <p>The buffered reader used to read from this server</p>
+     */
+    public BufferedReader getReader() {
+        return this.reader;
+    }
+
     /**
      * Tries to stop all enabled servers.
      *
@@ -357,21 +371,6 @@ public class Server implements java.io.Serializable {
         }
     }
 
-    /**
-     * Reads all available output from the server process
-     *
-     * @return <p>The server output</p>
-     * @throws IOException <p>If reading from the reader fails</p>
-     */
-    public String readFromServer() throws IOException {
-        String line;
-        StringBuilder text = new StringBuilder();
-        while (reader.ready() && (line = reader.readLine()) != null) {
-            text.append(line).append("\n");
-        }
-        return text.toString().trim();
-    }
-
     /**
      * Starts the process running this server
      *

src/main/java/net/knarcraft/minecraftserverlauncher/server/ServerVersionContainer.java

@@ -1,9 +1,19 @@
 package net.knarcraft.minecraftserverlauncher.server;
 
+import net.knarcraft.minecraftserverlauncher.Main;
+import net.knarcraft.minecraftserverlauncher.utility.CommonFunctions;
+
+import java.io.*;
+import java.util.HashMap;
 import java.util.Map;
 
+/**
+ * This class acts as a container for all "latest" server versions
+ */
 public class ServerVersionContainer implements java.io.Serializable {
 
+    private static ServerVersionContainer serverVersionContainer;
+    private String versionFile = Main.getApplicationWorkDirectory() + File.separator + "files" + File.separator + "versions.csv";
     private String vanillaVersion;
     private String snapshotVersion;
     private String bungeeVersion;
@@ -11,10 +21,157 @@ public class ServerVersionContainer implements java.io.Serializable {
     private String travertineVersion;
     private Map<String, String> spongeVanillaVersions;
 
-    public ServerVersionContainer() {
-
+    /**
+     * Initializes a new server version container
+     */
+    private ServerVersionContainer() {
+        spongeVanillaVersions = new HashMap<>();
+        loadState();
     }
 
+    /**
+     * Gives a server version container instance
+     *
+     * @return <p>A server version container instance</p>
+     */
+    public static ServerVersionContainer getInstance() {
+        if (serverVersionContainer == null) {
+            serverVersionContainer = new ServerVersionContainer();
+        }
+        return serverVersionContainer;
+    }
+
+    /**
+     * Resets the state of the server version container
+     */
+    public void reset() {
+        this.vanillaVersion = null;
+        this.snapshotVersion = null;
+        this.bungeeVersion = null;
+        this.waterfallVersion = null;
+        this.travertineVersion = null;
+        this.spongeVanillaVersions = new HashMap<>();
+    }
+
+    @Override
+    public String toString() {
+        return "vanillaVersion;" + vanillaVersion + "\n" +
+                "snapshotVersion;" + snapshotVersion + "\n" +
+                "bungeeVersion;" + bungeeVersion + "\n" +
+                "waterfallVersion;" + waterfallVersion + "\n" +
+                "travertineVersion;" + travertineVersion + "\n" +
+                "spongeVanillaVersions;" +
+                mapToString(spongeVanillaVersions);
+    }
+
+    /**
+     * Formats a map to a string given a map
+     *
+     * @param targetMap <p>The map to format</p>
+     * @return <p>A string representing the map</p>
+     */
+    private String mapToString(Map<?, ?> targetMap) {
+        StringBuilder stringBuilder = new StringBuilder();
+        int mapSize = targetMap.keySet().size();
+        int mapIndex = 0;
+        for (Object key : targetMap.keySet()) {
+            stringBuilder.append(key).append("!").append(targetMap.get(key));
+            if (mapIndex < mapSize) {
+                stringBuilder.append(",");
+            }
+            mapIndex++;
+        }
+        return stringBuilder.toString();
+    }
+
+    /**
+     * Tries to save the state of this server version container
+     */
+    public void saveState() {
+        PrintWriter file;
+        try {
+            file = new PrintWriter(versionFile);
+            file.println(this.toString());
+            file.close();
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * Loads the object state from the save file
+     */
+    private void loadState() {
+        BufferedReader reader;
+        if (!new File(versionFile).exists()) {
+            return;
+        }
+        try {
+            reader = new BufferedReader(new InputStreamReader(new FileInputStream(versionFile)));
+            String currentData = CommonFunctions.readBufferedReader(reader);
+            for (String line : currentData.split("\n")) {
+                parseSaveLine(line);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * Parses one line in the version save file and updates the appropriate variable
+     *
+     * @param line <p>The line from the save file to parse</p>
+     */
+    private void parseSaveLine(String line) {
+        String[] lineData = line.split(";");
+        if (lineData.length != 2) {
+            return;
+        }
+        String variableKey = lineData[0];
+        String variableValue = lineData[1];
+        switch (variableKey) {
+            case "vanillaVersion":
+                vanillaVersion = variableValue;
+                break;
+            case "snapshotVersion":
+                snapshotVersion = variableValue;
+                break;
+            case "bungeeVersion":
+                bungeeVersion = variableValue;
+                break;
+            case "waterfallVersion":
+                waterfallVersion = variableValue;
+                break;
+            case "travertineVersion":
+                travertineVersion = variableValue;
+                break;
+            case "spongeVanillaVersions":
+                parseSpongeVanillaVersions(variableValue);
+                break;
+            default:
+                throw new IllegalArgumentException("Invalid key encountered in the server version file.");
+        }
+    }
+
+    /**
+     * Reads spongeVanilla versions from a text string and updates the version map
+     *
+     * @param data <p>The data string to parse</p>
+     */
+    private void parseSpongeVanillaVersions(String data) {
+        String[] versions = data.split(",");
+        for (String version : versions) {
+            String[] versionData = version.split("!");
+            spongeVanillaVersions.put(versionData[0], versionData[1]);
+        }
+    }
+
+
+    /**
+     * Gets the current vanilla version
+     *
+     * @return <p>The current vanilla version</p>
+     */
     public String getVanillaVersion() {
         return this.vanillaVersion;
     }
@@ -23,65 +180,126 @@ public class ServerVersionContainer implements java.io.Serializable {
      * Sets the vanilla server version
      *
      * @param newVersion <p>The new vanilla server version</p>
-     * @return <p>This object</p>
      */
-    public ServerVersionContainer setVanillaVersion(String newVersion) {
+    public void setVanillaVersion(String newVersion) {
         this.vanillaVersion = newVersion;
-        return this;
+        saveState();
     }
 
+    /**
+     * Gets the current snapshot version
+     *
+     * @return <p>The current snapshot version</p>
+     */
     public String getSnapshotVersion() {
         return this.snapshotVersion;
     }
 
-    public ServerVersionContainer setSnapshotVersion(String newVersion) {
+    /**
+     * Sets the snapshot server version
+     *
+     * @param newVersion <p>The new snapshot server version</p>
+     */
+    public void setSnapshotVersion(String newVersion) {
         this.snapshotVersion = newVersion;
-        return this;
+        saveState();
     }
 
+    /**
+     * Gets the current bungee version
+     *
+     * @return <p>The current bungee version</p>
+     */
     public String getBungeeVersion() {
         return this.bungeeVersion;
     }
 
-    public ServerVersionContainer setBungeeVersion(String newVersion) {
+    /**
+     * Sets the bungee server version
+     *
+     * @param newVersion <p>The new bungee server version</p>
+     */
+    public void setBungeeVersion(String newVersion) {
         this.bungeeVersion = newVersion;
-        return this;
+        saveState();
     }
 
+    /**
+     * Gets the current waterfall version
+     *
+     * @return <p>The current waterfall version</p>
+     */
     public String getWaterfallVersion() {
         return this.waterfallVersion;
     }
 
-    public ServerVersionContainer setWaterfallVersion(String newVersion) {
+    /**
+     * Sets the waterfall server version
+     *
+     * @param newVersion <p>The new waterfall server version</p>
+     */
+    public void setWaterfallVersion(String newVersion) {
         this.waterfallVersion = newVersion;
-        return this;
+        saveState();
     }
 
+    /**
+     * Gets the current travertine server version
+     *
+     * @return <p>The current travertine version</p>
+     */
     public String getTravertineVersion() {
         return this.travertineVersion;
     }
 
-    public ServerVersionContainer setTravertineVersion(String newVersion) {
+    /**
+     * Sets the travertine server version
+     *
+     * @param newVersion <p>The new travertine server version</p>
+     */
+    public void setTravertineVersion(String newVersion) {
         this.travertineVersion = newVersion;
-        return this;
+        saveState();
     }
 
+    /**
+     * Gets the entire sponge vanilla version map
+     *
+     * @return <p>The entire sponge vanilla version map</p>
+     */
     public Map<String, String> getSpongeVanillaVersions() {
         return this.spongeVanillaVersions;
     }
 
+    /**
+     * Gets a specific sponge vanilla version
+     *
+     * @param versionKey <p>The version to check current version of</p>
+     * @return <p>The current sponge vanilla version</p>
+     */
     public String getSpongeVanillaVersion(String versionKey) {
         return spongeVanillaVersions.get(versionKey);
     }
 
-    public ServerVersionContainer setSpongeVanillaVersion(Map<String, String> newVersions) {
+    /**
+     * Replaces the entire sponge vanilla version map
+     *
+     * @param newVersions <p>The new version map to use</p>
+     */
+    public void setSpongeVanillaVersion(Map<String, String> newVersions) {
         this.spongeVanillaVersions = newVersions;
-        return this;
+        saveState();
     }
 
-    public ServerVersionContainer setSpongeVanillaVersion(String mapKey, String newValue) {
+    /**
+     * Sets the current version for a given sponge vanilla version
+     *
+     * @param mapKey   <p>The version key to set version for</p>
+     * @param newValue <p>The new current version</p>
+     */
+    public void setSpongeVanillaVersion(String mapKey, String newValue) {
         spongeVanillaVersions.put(mapKey, newValue);
-        return this;
+        saveState();
     }
 
 }

src/main/java/net/knarcraft/minecraftserverlauncher/server/servertypes/BungeeCord.java

@@ -1,5 +1,7 @@
 package net.knarcraft.minecraftserverlauncher.server.servertypes;
 
+import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
+
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Paths;
@@ -11,7 +13,6 @@ import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.stri
 public class BungeeCord extends AbstractServerType {
 
     private String versionURL;
-    private String lastVersion;
     private String srcStart;
     private String srcEnd;
 
@@ -35,11 +36,20 @@ public class BungeeCord extends AbstractServerType {
 
     @Override
     public boolean downloadJar(String folder, String version) throws IOException {
+        ServerVersionContainer versionContainer = ServerVersionContainer.getInstance();
         String file = this.getName() + version + ".jar";
         File filePath = new File(folder + file);
         String newestVersion = stringBetween(readFile(versionURL), srcStart, srcEnd);
-        String oldVersion = lastVersion;
-        lastVersion = newestVersion;
-        return (filePath.isFile() && newestVersion.equals(oldVersion)) || downloadFile(downloadURL, Paths.get(filePath.toURI()));
+        String oldVersion = versionContainer.getBungeeVersion();
+        //The file is already the newest version
+        if (filePath.isFile() && newestVersion.equals(oldVersion)) {
+            return true;
+        }
+        //The new jar file could not be downloaded
+        if (!downloadFile(downloadURL, Paths.get(filePath.toURI()))) {
+            return false;
+        }
+        versionContainer.setBungeeVersion(newestVersion);
+        return true;
     }
 }

src/main/java/net/knarcraft/minecraftserverlauncher/server/servertypes/SpongeVanilla.java

@@ -1,5 +1,6 @@
 package net.knarcraft.minecraftserverlauncher.server.servertypes;
 
+import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
 import net.knarcraft.minecraftserverlauncher.utility.CommonFunctions;
 
 import java.io.File;
@@ -11,7 +12,6 @@ import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.down
 public class SpongeVanilla extends AbstractServerType {
 
     private String versionURL;
-    private String lastVersion;
     private String srcStart;
     private String srcEnd;
     private String downloadURLPart;
@@ -39,6 +39,7 @@ public class SpongeVanilla extends AbstractServerType {
 
     @Override
     public boolean downloadJar(String folder, String version) throws IOException {
+        ServerVersionContainer versionContainer = ServerVersionContainer.getInstance();
         String file = this.getName() + version + ".jar";
         File filePath = new File(folder + file);
 
@@ -46,9 +47,17 @@ public class SpongeVanilla extends AbstractServerType {
         String newestVersion = CommonFunctions.stringBetween(versionText, srcStart, srcEnd);
 
         String jarURL = downloadURL + newestVersion + downloadURLPart + newestVersion + ".jar";
-        String oldVersion = lastVersion;
-        lastVersion = newestVersion;
 
-        return (filePath.isFile() && newestVersion.equals(oldVersion)) || downloadFile(jarURL, Paths.get(filePath.toURI()));
+        String oldVersion = versionContainer.getSpongeVanillaVersion(version);
+        //The file is already the newest version
+        if (filePath.isFile() && newestVersion.equals(oldVersion)) {
+            return true;
+        }
+        //The new jar file could not be downloaded
+        if (!downloadFile(jarURL, Paths.get(filePath.toURI()))) {
+            return false;
+        }
+        versionContainer.setSpongeVanillaVersion(version, newestVersion);
+        return true;
     }
 }

src/main/java/net/knarcraft/minecraftserverlauncher/server/servertypes/Travertine.java

@@ -1,5 +1,7 @@
 package net.knarcraft.minecraftserverlauncher.server.servertypes;
 
+import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
+
 public class Travertine extends Waterfall {
 
     /**
@@ -13,8 +15,11 @@ public class Travertine extends Waterfall {
      * @param srcEnd      <p>The string marking the end of the version id</p>
      * @param downloadURL <p>The URL used for downloading the latest version</p>
      */
-    public Travertine(String typeName, boolean isProxy, String[] versions, String versionURL, String srcStart, String srcEnd, String downloadURL) {
+    public Travertine(String typeName, boolean isProxy, String[] versions, String versionURL, String srcStart,
+                      String srcEnd, String downloadURL) {
         super(typeName, isProxy, versions, versionURL, srcStart, srcEnd, downloadURL);
+        this.oldVersion = ServerVersionContainer.getInstance().getTravertineVersion();
+        this.versionUpdateFunction = (newVersion) -> serverVersionContainer.setTravertineVersion(newVersion);
     }
 
 }

src/main/java/net/knarcraft/minecraftserverlauncher/server/servertypes/Vanilla.java

@@ -4,6 +4,7 @@ import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
+import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
 
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -19,8 +20,6 @@ import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.read
 public class Vanilla extends AbstractServerType {
 
     private final String versionURL;
-    private String lastVanillaVersion;
-    private String lastSnapshotVersion;
 
     /**
      * Instantiates a vanilla server type
@@ -38,12 +37,14 @@ public class Vanilla extends AbstractServerType {
 
     @Override
     public boolean downloadJar(String folder, String version) throws IOException {
+        ServerVersionContainer versionContainer = ServerVersionContainer.getInstance();
         String file = this.getName() + version + ".jar";
         File filePath = new File(folder + file);
         if (version.equals("Latest") || version.equals("Snapshot")) {
             String releaseType = version.equals("Latest") ? "release" : "snapshot";
-            String lastVersion = version.equals("Latest") ? lastVanillaVersion : lastSnapshotVersion;
-            return downloadLatestJar(filePath, releaseType, lastVersion);
+            String lastVersion = version.equals("Latest") ? versionContainer.getVanillaVersion() :
+                    versionContainer.getSnapshotVersion();
+            return downloadLatestJar(filePath, releaseType, lastVersion, versionContainer);
         } else {
             String downloadURL = getVanillaDownloadURL(getServerFileVersionURL(version));
             return filePath.isFile() || downloadFile(downloadURL, Paths.get(filePath.toURI()));
@@ -56,19 +57,29 @@ public class Vanilla extends AbstractServerType {
      * @param filePath    <p>The path of the jar file to download</p>
      * @param releaseType <p>The release type used for downloading</p>
      * @param lastVersion <p>The last server version found</p>
+     * @param versionContainer <p>The version container to use</p>
      * @return <p>True if the jar exists and is the latest version or was downloaded</p>
      * @throws IOException <p>If the .jar cannot be downloaded</p>
      */
-    private boolean downloadLatestJar(File filePath, String releaseType, String lastVersion) throws IOException {
+    private boolean downloadLatestJar(File filePath, String releaseType, String lastVersion,
+                                      ServerVersionContainer versionContainer) throws IOException {
         String[] latestData = getLatestFile(releaseType);
         String latest = latestData[0];
         String jarFile = latestData[1];
-        if (releaseType.equals("release")) {
-            lastVanillaVersion = latest;
-        } else {
-            lastSnapshotVersion = latest;
+        //The file is already the newest version
+        if (filePath.isFile() && latest.equals(lastVersion)) {
+            return true;
         }
-        return (filePath.isFile() && latest.equals(lastVersion)) || downloadFile(jarFile, Paths.get(filePath.toURI()));
+        //The new jar file could not be downloaded
+        if (!downloadFile(jarFile, Paths.get(filePath.toURI()))) {
+            return false;
+        }
+        if (releaseType.equals("release")) {
+            versionContainer.setVanillaVersion(latest);
+        } else {
+            versionContainer.setSnapshotVersion(latest);
+        }
+        return true;
     }
 
     /**

src/main/java/net/knarcraft/minecraftserverlauncher/server/servertypes/Waterfall.java

@@ -1,8 +1,12 @@
 package net.knarcraft.minecraftserverlauncher.server.servertypes;
 
+import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
+
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Paths;
+import java.util.function.Consumer;
+import java.util.function.Function;
 
 import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.downloadFile;
 import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.readFile;
@@ -13,7 +17,9 @@ public class Waterfall extends AbstractServerType {
     private String srcStart;
     private String srcEnd;
     private String versionURL;
-    private String lastVersion;
+    String oldVersion;
+    Consumer<String> versionUpdateFunction;
+    ServerVersionContainer serverVersionContainer;
 
     /**
      * Instantiates a new Waterfall server type
@@ -29,9 +35,12 @@ public class Waterfall extends AbstractServerType {
     public Waterfall(String typeName, boolean isProxy, String[] versions, String versionURL, String srcStart,
                      String srcEnd, String downloadURL) {
         super(typeName, isProxy, versions, downloadURL);
+        this.serverVersionContainer = ServerVersionContainer.getInstance();
         this.srcStart = srcStart;
         this.srcEnd = srcEnd;
         this.versionURL = versionURL;
+        this.oldVersion = serverVersionContainer.getWaterfallVersion();
+        this.versionUpdateFunction = (newVersion) -> serverVersionContainer.setWaterfallVersion(newVersion);
     }
 
     @Override
@@ -39,9 +48,16 @@ public class Waterfall extends AbstractServerType {
         String file = this.getName() + version + ".jar";
         File filePath = new File(folder + file);
         String newestVersion = stringBetween(readFile(versionURL), srcStart, srcEnd);
-        String oldVersion = lastVersion;
-        lastVersion = newestVersion;
         String fullURL = downloadURL + newestVersion + "/download";
-        return (filePath.isFile() && newestVersion.equals(oldVersion)) || downloadFile(fullURL, Paths.get(filePath.toURI()));
+        //The file is already the newest version
+        if (filePath.isFile() && newestVersion.equals(this.oldVersion)) {
+            return true;
+        }
+        //The new jar file could not be downloaded
+        if (!downloadFile(fullURL, Paths.get(filePath.toURI()))) {
+            return false;
+        }
+        versionUpdateFunction.accept(newestVersion);
+        return true;
     }
 }

src/main/java/net/knarcraft/minecraftserverlauncher/utility/CommonFunctions.java

@@ -2,13 +2,7 @@ package net.knarcraft.minecraftserverlauncher.utility;
 
 import net.knarcraft.minecraftserverlauncher.userinterface.ServerLauncherGUI;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
+import java.io.*;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
@@ -161,4 +155,20 @@ public final class CommonFunctions {
             e1.printStackTrace();
         }
     }
+
+    /**
+     * Reads all lines from a buffered reader
+     *
+     * @param reader <p>The buffered reader to read from</p>
+     * @return <p>All lines currently readable from the reader, split by the \n character</p>
+     * @throws IOException <p>If unable to read from the buffered reader</p>
+     */
+    public static String readBufferedReader(BufferedReader reader) throws IOException {
+        String line;
+        StringBuilder text = new StringBuilder();
+        while (reader.ready() && (line = reader.readLine()) != null) {
+            text.append(line).append("\n");
+        }
+        return text.toString().trim();
+    }
 }

src/test/java/net/knarcraft/minecraftserverlauncher/server/ServerVersionContainerTest.java

@@ -0,0 +1,38 @@
+package net.knarcraft.minecraftserverlauncher.server;
+
+import net.knarcraft.minecraftserverlauncher.Main;
+import net.knarcraft.minecraftserverlauncher.utility.CommonFunctions;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.*;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class ServerVersionContainerTest {
+
+    private String versionFile = Main.getApplicationWorkDirectory() + File.separator + "files" + File.separator + "versions.csv";
+    private ServerVersionContainer serverVersionContainer;
+
+    @Before
+    public void setUp() {
+        serverVersionContainer = ServerVersionContainer.getInstance();
+    }
+
+    @Test
+    public void toStringTest() {
+        serverVersionContainer.reset();
+        assertEquals("vanillaVersion;null\nsnapshotVersion;null\nbungeeVersion;null\nwaterfallVersion;null\n" +
+                        "travertineVersion;null\nspongeVanillaVersions;",
+                serverVersionContainer.toString());
+    }
+
+    @Test
+    public void saveStateTest() throws IOException {
+        serverVersionContainer.saveState();
+        BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(versionFile)));
+        String savedData = CommonFunctions.readBufferedReader(reader);
+        assertEquals(serverVersionContainer.toString(), savedData);
+    }
+
+}

src/test/java/net/knarcraft/minecraftserverlauncher/utility/JarDownloaderTest.java

@@ -100,7 +100,11 @@ public class JarDownloaderTest {
      * Removes downloaded test jars
      */
     private static void removeDownloadedFiles() {
-        File[] oldFiles = new File(targetDirectory).listFiles();
+        File target = new File(targetDirectory);
+        if (!target.exists() && !target.mkdirs()) {
+            throw new IllegalArgumentException("Unable to create the test files directory");
+        }
+        File[] oldFiles = target.listFiles();
         if (oldFiles == null) {
             throw new IllegalArgumentException("Unable to list files in jar test directory");
         }