From ece765bed394d88699b09a5d090169d41c9fa59d Mon Sep 17 00:00:00 2001
From: chenyuheng <pass@chenyuheng.cn>
Date: Sun, 31 May 2020 15:05:50 +0800
Subject: [PATCH 1/9] add checking connection function

as https://github.com/JabRef/jabref/issues/6560 suggested
---
 .../jabref/gui/preferences/NetworkTab.fxml    |  2 +
 .../gui/preferences/NetworkTabView.java       |  8 +++
 .../gui/preferences/NetworkTabViewModel.java  | 54 +++++++++++++++++++
 .../org/jabref/logic/net/URLDownload.java     | 12 +++++
 4 files changed, 76 insertions(+)

diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTab.fxml b/src/main/java/org/jabref/gui/preferences/NetworkTab.fxml
index 77c3f00a629..148f7a50873 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTab.fxml
@@ -53,5 +53,7 @@
                              GridPane.rowIndex="5"/>
         <Label fx:id="proxyAttentionLabel" styleClass="warning-message"
                text="%Attention: Password is stored in plain text!" GridPane.columnIndex="2" GridPane.rowIndex="5"/>
+        <Button fx:id="checkConnectionButton" text="%Check connection" onAction="#checkConnection"
+                prefWidth="200.0" GridPane.columnIndex="1" GridPane.rowIndex="6"/>
     </GridPane>
 </fx:root>
diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabView.java b/src/main/java/org/jabref/gui/preferences/NetworkTabView.java
index 245d5f3ed5b..dc40573bcbd 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabView.java
@@ -40,6 +40,7 @@ public class NetworkTabView extends AbstractPreferenceTabView<NetworkTabViewMode
     @FXML private Label proxyPasswordLabel;
     @FXML private CustomPasswordField proxyPassword;
     @FXML private Label proxyAttentionLabel;
+    @FXML private Button checkConnectionButton;
 
     private String proxyPasswordText = "";
     private int proxyPasswordCaretPosition = 0;
@@ -91,6 +92,8 @@ public void initialize() {
         proxyPassword.getRight().addEventFilter(MouseEvent.MOUSE_RELEASED, this::proxyPasswordMask);
         proxyPassword.getRight().addEventFilter(MouseEvent.MOUSE_EXITED, this::proxyPasswordMask);
 
+        checkConnectionButton.disableProperty().bind(proxyUse.selectedProperty().not());
+
         ActionFactory actionFactory = new ActionFactory(Globals.getKeyPrefs());
         actionFactory.configureIconButton(StandardActions.HELP, new HelpAction(HelpFile.REMOTE), remoteHelp);
 
@@ -120,4 +123,9 @@ private void proxyPasswordMask(MouseEvent event) {
             proxyPasswordCaretPosition = 0;
         }
     }
+
+    @FXML
+    void checkConnection() {
+        viewModel.checkConnection();
+    }
 }
diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
index 80f7d71b5cf..9acbbae48ea 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
@@ -1,5 +1,6 @@
 package org.jabref.gui.preferences;
 
+import java.net.MalformedURLException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
@@ -9,12 +10,19 @@
 import javafx.beans.property.SimpleStringProperty;
 import javafx.beans.property.StringProperty;
 
+import javafx.scene.control.ButtonType;
+import javafx.scene.control.DialogPane;
+import javafx.scene.control.Label;
+import javafx.scene.control.TextField;
+import javafx.scene.layout.GridPane;
+import kong.unirest.UnirestException;
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
 import org.jabref.gui.remote.JabRefMessageHandler;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.net.ProxyPreferences;
 import org.jabref.logic.net.ProxyRegisterer;
+import org.jabref.logic.net.URLDownload;
 import org.jabref.logic.remote.RemotePreferences;
 import org.jabref.logic.remote.RemoteUtil;
 import org.jabref.model.strings.StringUtil;
@@ -215,6 +223,52 @@ public boolean validateSettings() {
         return true;
     }
 
+    public void checkConnection() {
+        DialogPane dialogPane = new DialogPane();
+        GridPane settingsPane = new GridPane();
+        settingsPane.setHgap(4.0);
+        settingsPane.setVgap(4.0);
+
+        Label messageLabel = new Label();
+        messageLabel.setText(Localization.lang("Warning: your settings will be saved.\nEnter any URL to check connection to:"));
+
+        TextField url = new TextField();
+        url.setText("http://");
+
+        settingsPane.add(messageLabel, 1, 0);
+
+        settingsPane.add(url, 1, 1);
+        dialogPane.setContent(settingsPane);
+        String title = Localization.lang("Check Proxy Setting");
+        dialogService.showCustomDialogAndWait(
+                title,
+                dialogPane,
+                ButtonType.OK, ButtonType.CANCEL)
+                .ifPresent(btn -> {
+                            if (btn == ButtonType.OK) {
+                                String connectionProblemText = Localization.lang("Problem with connection: ");
+                                String connectionSuccessText = Localization.lang("Connection Successful!");
+                                storeProxySettings();
+                                System.out.println(url.getText());
+                                URLDownload dl;
+                                try {
+                                    dl = new URLDownload(url.getText());
+                                    int connectionStatus = dl.checkConnection();
+                                    if (connectionStatus == 200) {
+                                        dialogService.showInformationDialogAndWait(title, connectionSuccessText);
+                                    } else {
+                                        dialogService.showErrorDialogAndWait(title, connectionProblemText + Localization.lang("Request failed with status code ") + connectionStatus);
+                                    }
+                                } catch (MalformedURLException e) {
+                                    dialogService.showErrorDialogAndWait(title, connectionProblemText + e.getMessage());
+                                } catch (UnirestException e) {
+                                    dialogService.showErrorDialogAndWait(title, connectionProblemText + e.getMessage());
+                                }
+                            }
+                        }
+                );
+    }
+
     @Override
     public List<String> getRestartWarnings() {
         return restartWarning;
diff --git a/src/main/java/org/jabref/logic/net/URLDownload.java b/src/main/java/org/jabref/logic/net/URLDownload.java
index bf240352920..c72ee88110b 100644
--- a/src/main/java/org/jabref/logic/net/URLDownload.java
+++ b/src/main/java/org/jabref/logic/net/URLDownload.java
@@ -38,6 +38,7 @@
 import javax.net.ssl.TrustManager;
 import javax.net.ssl.X509TrustManager;
 
+import kong.unirest.UnirestException;
 import org.jabref.logic.util.io.FileUtil;
 import org.jabref.model.util.FileHelper;
 
@@ -171,6 +172,17 @@ public String getMimeType() {
         return "";
     }
 
+    public int checkConnection() {
+        Unirest.config().setDefaultHeader("User-Agent", "Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/2.0.0.6");
+        // Try to use HEAD request to avoid downloading the whole file
+        try {
+            int statusCode = Unirest.head(source.toString()).asString().getStatus();
+            return statusCode;
+        } catch (UnirestException e){
+            throw e;
+        }
+    }
+
     public boolean isMimeType(String type) {
         String mime = getMimeType();
 

From c3baca009bdd2929708444ba030b77194b30d921 Mon Sep 17 00:00:00 2001
From: chenyuheng <pass@chenyuheng.cn>
Date: Sun, 31 May 2020 15:41:11 +0800
Subject: [PATCH 2/9] checkstyle fix

---
 .../java/org/jabref/gui/preferences/NetworkTabViewModel.java  | 4 ++--
 src/main/java/org/jabref/logic/net/URLDownload.java           | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
index 9acbbae48ea..707c28cde1f 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
@@ -9,13 +9,12 @@
 import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleStringProperty;
 import javafx.beans.property.StringProperty;
-
 import javafx.scene.control.ButtonType;
 import javafx.scene.control.DialogPane;
 import javafx.scene.control.Label;
 import javafx.scene.control.TextField;
 import javafx.scene.layout.GridPane;
-import kong.unirest.UnirestException;
+
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
 import org.jabref.gui.remote.JabRefMessageHandler;
@@ -33,6 +32,7 @@
 import de.saxsys.mvvmfx.utils.validation.ValidationMessage;
 import de.saxsys.mvvmfx.utils.validation.ValidationStatus;
 import de.saxsys.mvvmfx.utils.validation.Validator;
+import kong.unirest.UnirestException;
 
 public class NetworkTabViewModel implements PreferenceTabViewModel {
     private final BooleanProperty remoteServerProperty = new SimpleBooleanProperty();
diff --git a/src/main/java/org/jabref/logic/net/URLDownload.java b/src/main/java/org/jabref/logic/net/URLDownload.java
index c72ee88110b..93f904ed71e 100644
--- a/src/main/java/org/jabref/logic/net/URLDownload.java
+++ b/src/main/java/org/jabref/logic/net/URLDownload.java
@@ -38,11 +38,11 @@
 import javax.net.ssl.TrustManager;
 import javax.net.ssl.X509TrustManager;
 
-import kong.unirest.UnirestException;
 import org.jabref.logic.util.io.FileUtil;
 import org.jabref.model.util.FileHelper;
 
 import kong.unirest.Unirest;
+import kong.unirest.UnirestException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -178,7 +178,7 @@ public int checkConnection() {
         try {
             int statusCode = Unirest.head(source.toString()).asString().getStatus();
             return statusCode;
-        } catch (UnirestException e){
+        } catch (UnirestException e) {
             throw e;
         }
     }

From 94d1386d2612682296198b5228be5aae86634298 Mon Sep 17 00:00:00 2001
From: chenyuheng <pass@chenyuheng.cn>
Date: Sun, 31 May 2020 15:46:29 +0800
Subject: [PATCH 3/9] add javadoc

---
 .../org/jabref/gui/preferences/NetworkTabViewModel.java     | 5 +++++
 src/main/java/org/jabref/logic/net/URLDownload.java         | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
index 707c28cde1f..4209ae8965d 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
@@ -223,6 +223,11 @@ public boolean validateSettings() {
         return true;
     }
 
+    /**
+     * Check the connection by using the given url. Used for validating the http proxy.
+     * The checking result will be appear when request finished.
+     * The checking result could be either success or fail, if fail, the cause will be displayed.
+     */
     public void checkConnection() {
         DialogPane dialogPane = new DialogPane();
         GridPane settingsPane = new GridPane();
diff --git a/src/main/java/org/jabref/logic/net/URLDownload.java b/src/main/java/org/jabref/logic/net/URLDownload.java
index 93f904ed71e..ea7d209c8e4 100644
--- a/src/main/java/org/jabref/logic/net/URLDownload.java
+++ b/src/main/java/org/jabref/logic/net/URLDownload.java
@@ -172,9 +172,13 @@ public String getMimeType() {
         return "";
     }
 
+    /**
+     * Check the connection by using the HEAD request.
+     * UnirestException can be thrown for invalid request.
+     * @return the status code of the response
+     */
     public int checkConnection() {
         Unirest.config().setDefaultHeader("User-Agent", "Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/2.0.0.6");
-        // Try to use HEAD request to avoid downloading the whole file
         try {
             int statusCode = Unirest.head(source.toString()).asString().getStatus();
             return statusCode;

From 3c2252b840a8b4955bc084354a1b62c99f6c89a5 Mon Sep 17 00:00:00 2001
From: chenyuheng <pass@chenyuheng.cn>
Date: Sun, 31 May 2020 16:10:20 +0800
Subject: [PATCH 4/9] add tests

---
 .../org/jabref/logic/net/URLDownloadTest.java | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/test/java/org/jabref/logic/net/URLDownloadTest.java b/src/test/java/org/jabref/logic/net/URLDownloadTest.java
index 89ea7b33183..d28d363ae2d 100644
--- a/src/test/java/org/jabref/logic/net/URLDownloadTest.java
+++ b/src/test/java/org/jabref/logic/net/URLDownloadTest.java
@@ -2,16 +2,20 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.MalformedURLException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 
 import org.jabref.support.DisabledOnCIServer;
 
+import kong.unirest.UnirestException;
 import org.junit.jupiter.api.Test;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class URLDownloadTest {
 
@@ -91,4 +95,24 @@ public void downloadOfHttpsSucceeds() throws IOException {
         Path path = ftp.toTemporaryFile();
         assertNotNull(path);
     }
+
+    @Test
+    public void testCheckConnectionSuccess() throws MalformedURLException {
+        URLDownload google = new URLDownload(new URL("http://www.google.com"));
+
+        int statusCode = google.checkConnection();
+        assertEquals(200, statusCode);
+    }
+
+    @Test
+    public void testCheckConnectionFail() throws MalformedURLException {
+        URLDownload nonsense = new URLDownload(new URL("http://nonsenseadddress"));
+        try {
+            int statusCode = nonsense.checkConnection();
+            fail();
+        } catch (UnirestException e) {
+            return;
+        }
+    }
+
 }

From 0816a99da555ed5ff6ff9b44f441c9c4034c2d2d Mon Sep 17 00:00:00 2001
From: chenyuheng <pass@chenyuheng.cn>
Date: Sun, 31 May 2020 16:21:07 +0800
Subject: [PATCH 5/9] trivial fix

---
 src/main/java/org/jabref/gui/preferences/NetworkTabView.java    | 2 --
 .../java/org/jabref/gui/preferences/NetworkTabViewModel.java    | 1 -
 2 files changed, 3 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabView.java b/src/main/java/org/jabref/gui/preferences/NetworkTabView.java
index dc40573bcbd..188ae138662 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabView.java
@@ -92,8 +92,6 @@ public void initialize() {
         proxyPassword.getRight().addEventFilter(MouseEvent.MOUSE_RELEASED, this::proxyPasswordMask);
         proxyPassword.getRight().addEventFilter(MouseEvent.MOUSE_EXITED, this::proxyPasswordMask);
 
-        checkConnectionButton.disableProperty().bind(proxyUse.selectedProperty().not());
-
         ActionFactory actionFactory = new ActionFactory(Globals.getKeyPrefs());
         actionFactory.configureIconButton(StandardActions.HELP, new HelpAction(HelpFile.REMOTE), remoteHelp);
 
diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
index 4209ae8965d..3306370db61 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
@@ -254,7 +254,6 @@ public void checkConnection() {
                                 String connectionProblemText = Localization.lang("Problem with connection: ");
                                 String connectionSuccessText = Localization.lang("Connection Successful!");
                                 storeProxySettings();
-                                System.out.println(url.getText());
                                 URLDownload dl;
                                 try {
                                     dl = new URLDownload(url.getText());

From 50af66413aec014790b045fe5207ae19e947831b Mon Sep 17 00:00:00 2001
From: chenyuheng <pass@chenyuheng.cn>
Date: Sun, 31 May 2020 16:36:54 +0800
Subject: [PATCH 6/9] Update CHANGELOG.md

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d8d7c5e7912..3ae5ab6a1cd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 - We added support for jumping to target entry when typing letter/digit after sorting a column in maintable [#6146](https://github.com/JabRef/jabref/issues/6146)
 - We added a new fetcher to enable users to search all available E-Libraries simultaneously. [koppor#369](https://github.com/koppor/jabref/issues/369)
 - We added the field "entrytype" to the export sort criteria [#6531](https://github.com/JabRef/jabref/pull/6531)
+- We added connection check function in network preference setting [#6560](https://github.com/JabRef/jabref/issues/6560)
 
 ### Changed
 

From 334d53ddc0a12cbca434e276c07bd94fca16c01a Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 2 Sep 2020 01:13:18 +0200
Subject: [PATCH 7/9] Removed dialog

---
 .../gui/preferences/NetworkTabViewModel.java  | 109 ++++++++----------
 1 file changed, 45 insertions(+), 64 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
index 3306370db61..48be438aa76 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
@@ -9,11 +9,6 @@
 import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleStringProperty;
 import javafx.beans.property.StringProperty;
-import javafx.scene.control.ButtonType;
-import javafx.scene.control.DialogPane;
-import javafx.scene.control.Label;
-import javafx.scene.control.TextField;
-import javafx.scene.layout.GridPane;
 
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
@@ -52,16 +47,16 @@ public class NetworkTabViewModel implements PreferenceTabViewModel {
 
     private final DialogService dialogService;
     private final PreferencesService preferences;
-    private final RemotePreferences remotePreferences;
-    private final ProxyPreferences proxyPreferences;
+    private final RemotePreferences initialRemotePreferences;
+    private final ProxyPreferences initialProxyPreferences;
 
     private final List<String> restartWarning = new ArrayList<>();
 
     public NetworkTabViewModel(DialogService dialogService, PreferencesService preferences) {
         this.dialogService = dialogService;
         this.preferences = preferences;
-        this.remotePreferences = preferences.getRemotePreferences();
-        this.proxyPreferences = preferences.getProxyPreferences();
+        this.initialRemotePreferences = preferences.getRemotePreferences();
+        this.initialProxyPreferences = preferences.getProxyPreferences();
 
         remotePortValidator = new FunctionBasedValidator<>(
                 remotePortProperty,
@@ -112,15 +107,19 @@ public NetworkTabViewModel(DialogService dialogService, PreferencesService prefe
     }
 
     public void setValues() {
-        remoteServerProperty.setValue(remotePreferences.useRemoteServer());
-        remotePortProperty.setValue(String.valueOf(remotePreferences.getPort()));
-
-        proxyUseProperty.setValue(proxyPreferences.isUseProxy());
-        proxyHostnameProperty.setValue(proxyPreferences.getHostname());
-        proxyPortProperty.setValue(proxyPreferences.getPort());
-        proxyUseAuthenticationProperty.setValue(proxyPreferences.isUseAuthentication());
-        proxyUsernameProperty.setValue(proxyPreferences.getUsername());
-        proxyPasswordProperty.setValue(proxyPreferences.getPassword());
+        remoteServerProperty.setValue(initialRemotePreferences.useRemoteServer());
+        remotePortProperty.setValue(String.valueOf(initialRemotePreferences.getPort()));
+
+        setProxyValues();
+    }
+
+    private void setProxyValues() {
+        proxyUseProperty.setValue(initialProxyPreferences.isUseProxy());
+        proxyHostnameProperty.setValue(initialProxyPreferences.getHostname());
+        proxyPortProperty.setValue(initialProxyPreferences.getPort());
+        proxyUseAuthenticationProperty.setValue(initialProxyPreferences.isUseAuthentication());
+        proxyUsernameProperty.setValue(initialProxyPreferences.getUsername());
+        proxyPasswordProperty.setValue(initialProxyPreferences.getPassword());
     }
 
     public void storeSettings() {
@@ -130,12 +129,12 @@ public void storeSettings() {
 
     private void storeRemoteSettings() {
         RemotePreferences newRemotePreferences = new RemotePreferences(
-                remotePreferences.getPort(),
+                initialRemotePreferences.getPort(),
                 remoteServerProperty.getValue()
         );
 
         getPortAsInt(remotePortProperty.getValue()).ifPresent(newPort -> {
-            if (remotePreferences.isDifferentPort(newPort)) {
+            if (initialRemotePreferences.isDifferentPort(newPort)) {
                 newRemotePreferences.setPort(newPort);
 
                 if (newRemotePreferences.useRemoteServer()) {
@@ -145,7 +144,7 @@ private void storeRemoteSettings() {
         });
 
         if (newRemotePreferences.useRemoteServer()) {
-            Globals.REMOTE_LISTENER.openAndStart(new JabRefMessageHandler(), remotePreferences.getPort());
+            Globals.REMOTE_LISTENER.openAndStart(new JabRefMessageHandler(), initialRemotePreferences.getPort());
         } else {
             Globals.REMOTE_LISTENER.stop();
         }
@@ -163,7 +162,7 @@ private void storeProxySettings() {
                 proxyPasswordProperty.getValue()
         );
 
-        if (!newProxyPreferences.equals(proxyPreferences)) {
+        if (!newProxyPreferences.equals(initialProxyPreferences)) {
             ProxyRegisterer.register(newProxyPreferences);
         }
         preferences.storeProxyPreferences(newProxyPreferences);
@@ -229,48 +228,30 @@ public boolean validateSettings() {
      * The checking result could be either success or fail, if fail, the cause will be displayed.
      */
     public void checkConnection() {
-        DialogPane dialogPane = new DialogPane();
-        GridPane settingsPane = new GridPane();
-        settingsPane.setHgap(4.0);
-        settingsPane.setVgap(4.0);
-
-        Label messageLabel = new Label();
-        messageLabel.setText(Localization.lang("Warning: your settings will be saved.\nEnter any URL to check connection to:"));
-
-        TextField url = new TextField();
-        url.setText("http://");
-
-        settingsPane.add(messageLabel, 1, 0);
-
-        settingsPane.add(url, 1, 1);
-        dialogPane.setContent(settingsPane);
-        String title = Localization.lang("Check Proxy Setting");
-        dialogService.showCustomDialogAndWait(
-                title,
-                dialogPane,
-                ButtonType.OK, ButtonType.CANCEL)
-                .ifPresent(btn -> {
-                            if (btn == ButtonType.OK) {
-                                String connectionProblemText = Localization.lang("Problem with connection: ");
-                                String connectionSuccessText = Localization.lang("Connection Successful!");
-                                storeProxySettings();
-                                URLDownload dl;
-                                try {
-                                    dl = new URLDownload(url.getText());
-                                    int connectionStatus = dl.checkConnection();
-                                    if (connectionStatus == 200) {
-                                        dialogService.showInformationDialogAndWait(title, connectionSuccessText);
-                                    } else {
-                                        dialogService.showErrorDialogAndWait(title, connectionProblemText + Localization.lang("Request failed with status code ") + connectionStatus);
-                                    }
-                                } catch (MalformedURLException e) {
-                                    dialogService.showErrorDialogAndWait(title, connectionProblemText + e.getMessage());
-                                } catch (UnirestException e) {
-                                    dialogService.showErrorDialogAndWait(title, connectionProblemText + e.getMessage());
-                                }
-                            }
-                        }
-                );
+        final String connectionProblemText = Localization.lang("Problem with connection: ");
+        final String connectionSuccessText = Localization.lang("Connection Successful!");
+        final String dialogTitle = Localization.lang("Check Proxy Setting");
+
+        final String testUrl = "http://jabref.org";
+
+        // Workaround for testing, since the URLDownload uses stored proxy settings, see
+        // preferences.storeProxyPreferences(...) below.
+        storeProxySettings();
+
+        URLDownload dl;
+        try {
+            dl = new URLDownload(testUrl);
+            int connectionStatus = dl.checkConnection();
+            if (connectionStatus == 200) {
+                dialogService.showInformationDialogAndWait(dialogTitle, connectionSuccessText);
+            } else {
+                dialogService.showErrorDialogAndWait(dialogTitle, connectionProblemText + Localization.lang("Request failed with status code ") + connectionStatus);
+            }
+        } catch (MalformedURLException | UnirestException e) {
+            dialogService.showErrorDialogAndWait(dialogTitle, connectionProblemText + e.getMessage());
+        }
+
+        preferences.storeProxyPreferences(initialProxyPreferences);
     }
 
     @Override

From e02161a1cf83fe075391c937e9659178e582f79b Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 2 Sep 2020 01:45:49 +0200
Subject: [PATCH 8/9] Refactored according to remarks in PR

---
 .../gui/preferences/NetworkTabViewModel.java  | 19 ++++++++++---------
 .../org/jabref/logic/net/URLDownload.java     | 15 ++++++---------
 .../org/jabref/logic/net/URLDownloadTest.java | 14 ++++----------
 3 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
index 48be438aa76..fbfb7eceab4 100644
--- a/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/NetworkTabViewModel.java
@@ -228,8 +228,8 @@ public boolean validateSettings() {
      * The checking result could be either success or fail, if fail, the cause will be displayed.
      */
     public void checkConnection() {
-        final String connectionProblemText = Localization.lang("Problem with connection: ");
-        final String connectionSuccessText = Localization.lang("Connection Successful!");
+        final String connectionSuccessText = Localization.lang("Connection successful!");
+        final String connectionFailedText = Localization.lang("Connection failed!");
         final String dialogTitle = Localization.lang("Check Proxy Setting");
 
         final String testUrl = "http://jabref.org";
@@ -238,17 +238,18 @@ public void checkConnection() {
         // preferences.storeProxyPreferences(...) below.
         storeProxySettings();
 
-        URLDownload dl;
+        URLDownload urlDownload;
         try {
-            dl = new URLDownload(testUrl);
-            int connectionStatus = dl.checkConnection();
-            if (connectionStatus == 200) {
+            urlDownload = new URLDownload(testUrl);
+            if (urlDownload.canBeReached()) {
                 dialogService.showInformationDialogAndWait(dialogTitle, connectionSuccessText);
             } else {
-                dialogService.showErrorDialogAndWait(dialogTitle, connectionProblemText + Localization.lang("Request failed with status code ") + connectionStatus);
+                dialogService.showErrorDialogAndWait(dialogTitle, connectionFailedText);
             }
-        } catch (MalformedURLException | UnirestException e) {
-            dialogService.showErrorDialogAndWait(dialogTitle, connectionProblemText + e.getMessage());
+        } catch (MalformedURLException e) {
+            // Why would that happen? Because one of developers inserted a failing url in testUrl...
+        } catch (UnirestException e) {
+            dialogService.showErrorDialogAndWait(dialogTitle, connectionFailedText);
         }
 
         preferences.storeProxyPreferences(initialProxyPreferences);
diff --git a/src/main/java/org/jabref/logic/net/URLDownload.java b/src/main/java/org/jabref/logic/net/URLDownload.java
index 8532fbaefd5..eec18e1756a 100644
--- a/src/main/java/org/jabref/logic/net/URLDownload.java
+++ b/src/main/java/org/jabref/logic/net/URLDownload.java
@@ -175,16 +175,14 @@ public String getMimeType() {
     /**
      * Check the connection by using the HEAD request.
      * UnirestException can be thrown for invalid request.
+     *
      * @return the status code of the response
      */
-    public int checkConnection() {
+    public boolean canBeReached() throws UnirestException {
         Unirest.config().setDefaultHeader("User-Agent", "Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/2.0.0.6");
-        try {
-            int statusCode = Unirest.head(source.toString()).asString().getStatus();
-            return statusCode;
-        } catch (UnirestException e) {
-            throw e;
-        }
+
+        int statusCode = Unirest.head(source.toString()).asString().getStatus();
+        return statusCode >= 200 && statusCode < 300;
     }
 
     public boolean isMimeType(String type) {
@@ -305,8 +303,7 @@ public String toString() {
     }
 
     private void copy(InputStream in, Writer out, Charset encoding) throws IOException {
-        InputStream monitoredInputStream = in;
-        Reader r = new InputStreamReader(monitoredInputStream, encoding);
+        Reader r = new InputStreamReader(in, encoding);
         try (BufferedReader read = new BufferedReader(r)) {
 
             String line;
diff --git a/src/test/java/org/jabref/logic/net/URLDownloadTest.java b/src/test/java/org/jabref/logic/net/URLDownloadTest.java
index d28d363ae2d..f77f0fc2431 100644
--- a/src/test/java/org/jabref/logic/net/URLDownloadTest.java
+++ b/src/test/java/org/jabref/logic/net/URLDownloadTest.java
@@ -12,10 +12,9 @@
 import kong.unirest.UnirestException;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
 
 public class URLDownloadTest {
 
@@ -100,19 +99,14 @@ public void downloadOfHttpsSucceeds() throws IOException {
     public void testCheckConnectionSuccess() throws MalformedURLException {
         URLDownload google = new URLDownload(new URL("http://www.google.com"));
 
-        int statusCode = google.checkConnection();
-        assertEquals(200, statusCode);
+        assertTrue(google.canBeReached());
     }
 
     @Test
     public void testCheckConnectionFail() throws MalformedURLException {
         URLDownload nonsense = new URLDownload(new URL("http://nonsenseadddress"));
-        try {
-            int statusCode = nonsense.checkConnection();
-            fail();
-        } catch (UnirestException e) {
-            return;
-        }
+
+        assertThrows(UnirestException.class, nonsense::canBeReached);
     }
 
 }

From e7d620a1c93f2274f93c73e8fa9cb68d6f11054e Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 2 Sep 2020 01:57:59 +0200
Subject: [PATCH 9/9] Fixed CHANGELOG.md

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 62c7042f993..fb6e6014c23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 
 - We added a query parser and mapping layer to enable conversion of queries formulated in simplified lucene syntax by the user into api queries. [#6799](https://github.com/JabRef/jabref/pull/6799)
 - We added some basic functionality to customise the look of JabRef by importing a css theme file. [#5790](https://github.com/JabRef/jabref/issues/5790)
+- We added connection check function in network preference setting [#6560](https://github.com/JabRef/jabref/issues/6560)
 
 ### Changed
 
@@ -59,7 +60,6 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 - We added native support for biblatex-software [#6574](https://github.com/JabRef/jabref/issues/6574)
 - We added a missing restart warning for AutoComplete in the preferences dialog. [#6351](https://github.com/JabRef/jabref/issues/6351)
 - We added a note to the citation key pattern preferences dialog as a temporary workaround for a JavaFX bug, about committing changes in a table cell, if the focus is lost. [#5825](https://github.com/JabRef/jabref/issues/5825)
-- We added connection check function in network preference setting [#6560](https://github.com/JabRef/jabref/issues/6560)
 
 ### Changed