Default to null when database name is absent for server versions lower than 4.0

Author: Zhen Li

driver/src/main/java/org/neo4j/driver/internal/summary/InternalDatabaseInfo.java

@@ -18,13 +18,13 @@
  */
 package org.neo4j.driver.internal.summary;
 
-import org.neo4j.driver.summary.DatabaseInfo;
+import java.util.Objects;
 
-import static org.neo4j.driver.internal.messaging.request.MultiDatabaseUtil.ABSENT_DB_NAME;
+import org.neo4j.driver.summary.DatabaseInfo;
 
 public class InternalDatabaseInfo implements DatabaseInfo
 {
-    public static DatabaseInfo DEFAULT_DATABASE_INFO = new InternalDatabaseInfo( ABSENT_DB_NAME );
+    public static DatabaseInfo DEFAULT_DATABASE_INFO = new InternalDatabaseInfo( null );
 
     private final String name;
 
@@ -38,4 +38,31 @@ public String name()
     {
         return this.name;
     }
+
+    @Override
+    public boolean equals( Object o )
+    {
+        if ( this == o )
+        {
+            return true;
+        }
+        if ( o == null || getClass() != o.getClass() )
+        {
+            return false;
+        }
+        InternalDatabaseInfo that = (InternalDatabaseInfo) o;
+        return Objects.equals( name, that.name );
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return Objects.hash( name );
+    }
+
+    @Override
+    public String toString()
+    {
+        return "InternalDatabaseInfo{" + "name='" + name + '\'' + '}';
+    }
 }

driver/src/main/java/org/neo4j/driver/internal/summary/InternalResultSummary.java

@@ -171,6 +171,7 @@ public String toString()
         return "InternalResultSummary{" +
                "statement=" + statement +
                ", serverInfo=" + serverInfo +
+               ", databaseInfo=" + databaseInfo +
                ", statementType=" + statementType +
                ", counters=" + counters +
                ", plan=" + plan +

driver/src/main/java/org/neo4j/driver/internal/summary/InternalServerInfo.java

@@ -18,6 +18,8 @@
  */
 package org.neo4j.driver.internal.summary;
 
+import java.util.Objects;
+
 import org.neo4j.driver.internal.BoltServerAddress;
 import org.neo4j.driver.internal.util.ServerVersion;
 import org.neo4j.driver.summary.ServerInfo;
@@ -44,4 +46,31 @@ public String version()
     {
         return version;
     }
+
+    @Override
+    public boolean equals( Object o )
+    {
+        if ( this == o )
+        {
+            return true;
+        }
+        if ( o == null || getClass() != o.getClass() )
+        {
+            return false;
+        }
+        InternalServerInfo that = (InternalServerInfo) o;
+        return Objects.equals( address, that.address ) && Objects.equals( version, that.version );
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return Objects.hash( address, version );
+    }
+
+    @Override
+    public String toString()
+    {
+        return "InternalServerInfo{" + "address='" + address + '\'' + ", version='" + version + '\'' + '}';
+    }
 }

driver/src/main/java/org/neo4j/driver/summary/DatabaseInfo.java

@@ -25,6 +25,7 @@ public interface DatabaseInfo
 {
     /**
      * The name of the database where a {@link ResultSummary} is obtained from.
+     * Default to {@code null} if servers does not support multi-databases.
      * @return the name of the database where a {@link ResultSummary} is obtained from
      */
     String name();

driver/src/test/java/org/neo4j/driver/internal/util/MetadataExtractorTest.java

@@ -407,7 +407,7 @@ void shouldExtractDatabase()
     }
 
     @Test
-    void shouldDefaultToEmptyDatabaseName()
+    void shouldDefaultToNullDatabaseName()
     {
         // Given
         Map<String,Value> metadata = singletonMap( "no_db", value( "no_db" ) );
@@ -416,7 +416,7 @@ void shouldDefaultToEmptyDatabaseName()
         DatabaseInfo db = extractDatabaseInfo( metadata );
 
         // Then
-        assertEquals( "", db.name() );
+        assertNull( db.name() );
     }
 
     @Test