Makes sure all writers flushes before the end

The API user is likely to write a lot of data with them. This way the API is more "foolproof"

lib/sparesults/src/csv.rs

@@ -55,8 +55,9 @@ impl<W: Write> CsvSolutionsWriter<W> {
         Ok(())
     }
 
-    pub fn finish(self) -> W {
+    pub fn finish(mut self) -> io::Result<W> {
-        self.sink
+        self.sink.flush()?;
+        Ok(self.sink)
     }
 }
 
@@ -145,8 +146,9 @@ impl<W: Write> TsvSolutionsWriter<W> {
         Ok(())
     }
 
-    pub fn finish(self) -> W {
+    pub fn finish(mut self) -> io::Result<W> {
-        self.sink
+        self.sink.flush()?;
+        Ok(self.sink)
     }
 }
 
@@ -319,7 +321,7 @@ mod tests {
                     .filter_map(|(v, s)| s.as_ref().map(|s| (v.as_ref(), s.as_ref()))),
             )?;
         }
-        let result = writer.finish();
+        let result = writer.finish()?;
         assert_eq!(str::from_utf8(&result).unwrap(), "x,literal\r\nhttp://example/x,String\r\nhttp://example/x,\"String-with-dquote\"\"\"\r\n_:b0,Blank node\r\n,Missing 'x'\r\n,\r\nhttp://example/x,\r\n_:b1,String-with-lang\r\n_:b1,123");
         Ok(())
     }
@@ -337,7 +339,7 @@ mod tests {
                     .filter_map(|(v, s)| s.as_ref().map(|s| (v.as_ref(), s.as_ref()))),
             )?;
         }
-        let result = writer.finish();
+        let result = writer.finish()?;
         assert_eq!(str::from_utf8(&result).unwrap(), "?x\t?literal\n<http://example/x>\t\"String\"\n<http://example/x>\t\"String-with-dquote\\\"\"\n_:b0\t\"Blank node\"\n\t\"Missing 'x'\"\n\t\n<http://example/x>\t\n_:b1\t\"String-with-lang\"@en\n_:b1\t123");
         Ok(())
     }

lib/sparesults/src/json.rs

@@ -66,7 +66,9 @@ impl<W: Write> JsonSolutionsWriter<W> {
         self.writer.write_event(JsonEvent::EndArray)?;
         self.writer.write_event(JsonEvent::EndObject)?;
         self.writer.write_event(JsonEvent::EndObject)?;
-        Ok(self.writer.into_inner())
+        let mut inner = self.writer.into_inner();
+        inner.flush()?;
+        Ok(inner)
     }
 }
 

lib/sparesults/src/lib.rs

@@ -498,11 +498,11 @@ impl<W: Write> SolutionsWriter<W> {
 
     /// Writes the last bytes of the file.
     pub fn finish(self) -> io::Result<W> {
-        Ok(match self.formatter {
+        match self.formatter {
-            SolutionsWriterKind::Xml(write) => write.finish()?,
+            SolutionsWriterKind::Xml(write) => write.finish(),
-            SolutionsWriterKind::Json(write) => write.finish()?,
+            SolutionsWriterKind::Json(write) => write.finish(),
             SolutionsWriterKind::Csv(write) => write.finish(),
             SolutionsWriterKind::Tsv(write) => write.finish(),
-        })
+        }
     }
 }

lib/sparesults/src/xml.rs

@@ -85,7 +85,9 @@ impl<W: Write> XmlSolutionsWriter<W> {
     }
 
     pub fn finish(self) -> io::Result<W> {
-        self.do_finish().map_err(map_xml_error)
+        let mut inner = self.do_finish().map_err(map_xml_error)?;
+        inner.flush()?;
+        Ok(inner)
     }
 
     fn do_finish(mut self) -> Result<W, quick_xml::Error> {

lib/src/io/write.rs

@@ -144,12 +144,9 @@ impl<W: Write> TripleWriter<W> {
     /// Writes the last bytes of the file
     pub fn finish(self) -> io::Result<()> {
         match self.formatter {
-            TripleWriterKind::NTriples(_) => (),
+            TripleWriterKind::NTriples(mut writer) => writer.flush(),
-            TripleWriterKind::RdfXml(formatter) => {
+            TripleWriterKind::RdfXml(formatter) => formatter.finish()?.flush(), //TODO: remove flush when the next version of Rio is going to be released
-                formatter.finish()?;
         }
-        };
-        Ok(())
     }
 }
 
@@ -259,6 +256,8 @@ impl<W: Write> QuadWriter<W> {
     /// Writes the last bytes of the file
     #[allow(clippy::unused_self, clippy::unnecessary_wraps)]
     pub fn finish(self) -> io::Result<()> {
-        Ok(())
+        match self.formatter {
+            QuadWriterKind::NQuads(mut writer) | QuadWriterKind::TriG(mut writer) => writer.flush(),
+        }
     }
 }