test: [TTA: adjust] test adjustments that result in no change

Cases:

 - no features
 - features under target duration
 - features equal to target duration

test/test_adjusters.py

@@ -91,3 +91,31 @@ class TestTargetTimeAdjuster(unittest.TestCase):
             # test
             for time, margin, expected in test_cases:
                 self.assertEqual(tta._determine_margin(time, margin, strategy), expected)
+
+    def test_adjust_no_change(self):
+        """Test adjusting of list of Features using TTA -- no change to list of Features
+
+        Cases:
+         - no Features --> []
+         - [Features] with total time < target time --> unchanged list
+         - [Features] with total time = target time --> unchanged list
+
+        TODO: test with Features > target
+        """
+        with self.subTest("no Features"):
+            tta = adjusters.TargetTimeAdjuster()
+            self.assertEqual(tta.adjust(), [])
+
+        with self.subTest("Features < target time"):
+            features = []
+            for i in range(1, 5):
+                features.append(make_feature(duration=i*1.0))
+            tta = adjusters.TargetTimeAdjuster(features=features, target_time=20.0)
+            self.assertEqual(tta.adjust(), features)
+
+        with self.subTest("Features = target time"):
+            features = []
+            for i in range(1, 5):
+                features.append(make_feature(duration=i*1.0))
+            tta = adjusters.TargetTimeAdjuster(features=features, target_time=10.0)
+            self.assertEqual(tta.adjust(), features)