From ed81fc6b3ff58ba1207a22e6277cc2f3640c6ef4 Mon Sep 17 00:00:00 2001
From: Jamie Morton <jamietmorton@gmail.com>
Date: Wed, 17 Aug 2016 22:40:56 -0700
Subject: [PATCH] TST: Adding scenario where intersection yield empty tree,
 table, metadata

---
 gneiss/_formula.py           |  7 +++++++
 gneiss/tests/test_formula.py | 40 ++++++++++++++++++++++++++++++++++--
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/gneiss/_formula.py b/gneiss/_formula.py
index 420226d..ab63a6f 100644
--- a/gneiss/_formula.py
+++ b/gneiss/_formula.py
@@ -22,6 +22,13 @@ def _intersect_of_table_metadata_tree(table, metadata, tree):
     _table, _tree = match_tips(_table, tree)
     non_tips_no_name = [(n.name is None) for n in _tree.levelorder()
                         if not n.is_tip()]
+    if len(non_tips_no_name) == 0:
+        raise ValueError('There are no internal nodes in `tree` after'
+                         'intersection with `table`.')
+
+    if len(_table.index) == 0:
+        raise ValueError('There are no internal nodes in `table` after '
+                         'intersection with `metadata`.')
 
     if any(non_tips_no_name):
         _tree = rename_internal_nodes(_tree)
diff --git a/gneiss/tests/test_formula.py b/gneiss/tests/test_formula.py
index 419879c..c45259f 100644
--- a/gneiss/tests/test_formula.py
+++ b/gneiss/tests/test_formula.py
@@ -111,8 +111,44 @@ def test_ols_immutable(self):
         self.assertEqual(str(table), str(exp_table))
         self.assertEqual(str(exp_tree), str(tree))
 
-    def test_ols_empty(self):
-        pass
+    def test_ols_empty_table(self):
+        A = np.array  # aliasing for the sake of pep8
+        table = pd.DataFrame({
+            's1': ilr_inv(A([1., 1.])),
+            's2': ilr_inv(A([1., 2.])),
+            's3': ilr_inv(A([1., 3.])),
+            's4': ilr_inv(A([1., 4.])),
+            's5': ilr_inv(A([1., 5.])),
+            's6': ilr_inv(A([1., 5.]))},
+            index=['x', 'y', 'z']).T
+
+        tree = TreeNode.read(['((c,d),(b,a)Y2)Y1;'])
+        metadata = pd.DataFrame({
+            'lame': [1, 1, 1, 1, 1],
+            'real': [1, 2, 3, 4, 5]
+        }, index=['s1', 's2', 's3', 's4', 's5'])
+        with self.assertRaises(ValueError):
+            ols('real + lame', table, metadata, tree)
+
+    def test_ols_empty_metadata(self):
+        A = np.array  # aliasing for the sake of pep8
+        table = pd.DataFrame({
+            'k1': ilr_inv(A([1., 1.])),
+            'k2': ilr_inv(A([1., 2.])),
+            'k3': ilr_inv(A([1., 3.])),
+            'k4': ilr_inv(A([1., 4.])),
+            'k5': ilr_inv(A([1., 5.])),
+            'k6': ilr_inv(A([1., 5.]))},
+            index=['a', 'b', 'c']).T
+
+        tree = TreeNode.read(['((c,d),(b,a)Y2)Y1;'])
+        metadata = pd.DataFrame({
+            'lame': [1, 1, 1, 1, 1],
+            'real': [1, 2, 3, 4, 5]
+        }, index=['s1', 's2', 's3', 's4', 's5'])
+        with self.assertRaises(ValueError):
+            ols('real + lame', table, metadata, tree)
+
 
 if __name__ == '__main__':
     unittest.main()