Bugfix for Tables with empty cells make the column disappear. Closes #320

Author: aslakhellesoy

History.md

@@ -1,5 +1,6 @@
 ## [Git master](https://github.com/cucumber/cucumber-jvm/compare/v1.0.7...master)
 
+* [Core] Tables with empty cells make the column disappear ([#320](https://github.com/cucumber/cucumber-jvm/pull/320) Aslak Hellesøy, Gilles Philippart)
 * [Java] Add 'throws Exception' to generated Java stepdef snippets ([#318](https://github.com/cucumber/cucumber-jvm/issues/318), [#319](https://github.com/cucumber/cucumber-jvm/pull/319) Petter Måhlén)
 * [Core] Remove forced UTC timezone. ([#317](https://github.com/cucumber/cucumber-jvm/pull/317) Gilles Philippart)
 * [Core] Options (Command line or `@Cucumber.Options`) can be overriden with the `cucumber.options` system property. (Aslak Hellesøy)

core/src/main/java/cucumber/table/TableConverter.java

@@ -15,6 +15,7 @@
 import cucumber.table.xstream.ListOfObjectWriter;
 import gherkin.util.Mapper;
 
+import java.lang.reflect.Field;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.util.ArrayList;
@@ -67,12 +68,26 @@ public DataTable toTable(List<?> objects, String... columnNames) {
             objects = wrapLists((List<List<?>>) objects);
             writer = new ListOfListOfSingleValueWriter(this);
         } else {
-            writer = new ListOfObjectWriter(this);
+            if (columnNames.length == 0) {
+                // Figure out column names by looking at class
+                columnNames = fieldNames(objects.get(0).getClass());
+            }
+            writer = new ListOfObjectWriter(this, columnNames);
         }
         xStream.marshal(objects, writer);
         return writer.getDataTable();
     }
 
+    private String[] fieldNames(Class clazz) {
+        Field[] fields = clazz.getFields();
+        String[] fieldNames = new String[fields.length];
+        int i = 0;
+        for (Field field : fields) {
+            fieldNames[i++] = field.getName();
+        }
+        return fieldNames;
+    }
+
     // This is a hack to prevent XStream from outputting weird-looking "XML" for Arrays.asList() - created lists.
     private List<List<?>> wrapLists(List<List<?>> lists) {
         List<List<?>> result = new ArrayList<List<?>>();
@@ -95,10 +110,12 @@ public String map(String attributeName) {
     }
 
     private boolean isListOfListOfSingleValue(List<?> objects) {
-        if (objects.size() > 0 && objects.get(0) instanceof List) {
-            List firstList = (List) objects.get(0);
-            if (firstList.size() > 0 && isSingleValue(firstList.get(0).getClass())) {
-                return true;
+        for (Object object : objects) {
+            if (object instanceof List) {
+                List list = (List) object;
+                if (list.size() > 0 && isSingleValue(list.get(0).getClass())) {
+                    return true;
+                }
             }
         }
         return false;

core/src/main/java/cucumber/table/xstream/ListOfObjectWriter.java

@@ -8,18 +8,25 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 
 public class ListOfObjectWriter extends DataTableWriter {
     private static final List<Comment> NO_COMMENTS = emptyList();
     private final List<DataTableRow> rows = new ArrayList<DataTableRow>();
     private final TableConverter tableConverter;
+    private final List<String> fieldNames;
+
     private int nodeDepth = 0;
-    private List<String> header = new ArrayList<String>();
-    private List<String> cells;
+    private String[] fieldValues;
+    private int fieldIndex = -1;
 
-    public ListOfObjectWriter(TableConverter tableConverter) {
+    public ListOfObjectWriter(TableConverter tableConverter, String... columnNames) {
         this.tableConverter = tableConverter;
+        fieldNames = asList(columnNames);
+
+        DataTableRow headerRow = new DataTableRow(NO_COMMENTS, fieldNames, 0);
+        rows.add(headerRow);
     }
 
     @Override
@@ -31,10 +38,10 @@ public DataTable getDataTable() {
     public void startNode(String name) {
         nodeDepth++;
         if (nodeDepth == 2) {
-            cells = new ArrayList<String>();
+            fieldValues = new String[fieldNames.size()];
         }
-        if (nodeDepth == 3 && header != null) {
-            header.add(name);
+        if (nodeDepth == 3) {
+            fieldIndex = fieldNames.indexOf(name);
         }
     }
 
@@ -44,23 +51,33 @@ public void addAttribute(String name, String value) {
 
     @Override
     public void setValue(String text) {
-        cells.add(text);
+        if(fieldIndex != -1) {
+            fieldValues[fieldIndex] = text;
+        }
     }
 
     @Override
     public void endNode() {
         if (nodeDepth == 2) {
-            if (header != null) {
-                DataTableRow headerRow = new DataTableRow(NO_COMMENTS, header, 0);
-                rows.add(headerRow);
-                header = null;
-            }
+            List<String> cells = toArrayReplacingNullWithEmptyString();
             DataTableRow row = new DataTableRow(NO_COMMENTS, cells, 0);
             rows.add(row);
         }
         nodeDepth--;
     }
 
+    private List<String> toArrayReplacingNullWithEmptyString() {
+        List<String> cells = new ArrayList<String>(fieldValues.length);
+        for(int i = 0; i < fieldValues.length; i++) {
+            String fieldValue = fieldValues[i];
+            if(fieldValue == null) {
+                fieldValue = "";
+            }
+            cells.add(fieldValue);
+        }
+        return cells;
+    }
+
     @Override
     public void flush() {
         throw new UnsupportedOperationException();

core/src/test/java/cucumber/table/ToDataTableTest.java

@@ -84,7 +84,6 @@ public void gives_a_nice_error_message_when_primitive_field_is_null() {
     }
 
     @Test
-    @Ignore
     public void converts_list_of_beans_to_table_with_explicit_columns() {
         List<UserPojo> users = tc.toList(UserPojo.class, personTable());
         DataTable table = tc.toTable(users, "name", "birthDate", "credits");