Fix detection of "first row, not headline" (#63)

Improved handling of "first row, not headline".

Works for tables with
1) neither thead nor tbody
2) tbody but no thead

markdownify/__init__.py

@@ -370,8 +370,13 @@ class MarkdownConverter(object):
         if is_headrow and not el.previous_sibling:
             # first row and is headline: print headline underline
             underline += '| ' + ' | '.join(['---'] * len(cells)) + ' |' + '\n'
-        elif not el.previous_sibling and not el.parent.name != 'table':
+        elif (not el.previous_sibling
-            # first row, not headline, and the parent is sth. like tbody:
+              and (el.parent.name == 'table'
+                   or (el.parent.name == 'tbody'
+                       and not el.parent.previous_sibling))):
+            # first row, not headline, and:
+            # - the parent is table or
+            # - the parent is tbody at the beginning of a table.
             # print empty headline above this row
             overline += '| ' + ' | '.join([''] * len(cells)) + ' |' + '\n'
             overline += '| ' + ' | '.join(['---'] * len(cells)) + ' |' + '\n'

tests/test_tables.py

@@ -139,6 +139,26 @@ table_missing_head = """<table>
     </tr>
 </table>"""
 
+table_body = """<table>
+    <tbody>
+        <tr>
+            <td>Firstname</td>
+            <td>Lastname</td>
+            <td>Age</td>
+        </tr>
+        <tr>
+            <td>Jill</td>
+            <td>Smith</td>
+            <td>50</td>
+        </tr>
+        <tr>
+            <td>Eve</td>
+            <td>Jackson</td>
+            <td>94</td>
+        </tr>
+    </tbody>
+</table>"""
+
 
 def test_table():
     assert md(table) == '\n\n| Firstname | Lastname | Age |\n| --- | --- | --- |\n| Jill | Smith | 50 |\n| Eve | Jackson | 94 |\n\n'
@@ -148,3 +168,4 @@ def test_table():
     assert md(table_head_body) == '\n\n| Firstname | Lastname | Age |\n| --- | --- | --- |\n| Jill | Smith | 50 |\n| Eve | Jackson | 94 |\n\n'
     assert md(table_missing_text) == '\n\n|  | Lastname | Age |\n| --- | --- | --- |\n| Jill |  | 50 |\n| Eve | Jackson | 94 |\n\n'
     assert md(table_missing_head) == '\n\n|  |  |  |\n| --- | --- | --- |\n| Firstname | Lastname | Age |\n| Jill | Smith | 50 |\n| Eve | Jackson | 94 |\n\n'
+    assert md(table_body) == '\n\n|  |  |  |\n| --- | --- | --- |\n| Firstname | Lastname | Age |\n| Jill | Smith | 50 |\n| Eve | Jackson | 94 |\n\n'