Fix traceback when task or matrix has no env.

Signed-off-by: Chris Evich <cevich@redhat.com>

cirrus-ci_env/cirrus-ci_env.py

@@ -159,7 +159,7 @@ def unroll_matrix(self, name_default: str, alias_default: str,
                                  f" or matrix definition: {item}"
                                  f" for task definition: {task}")
             # default values for the rendered task - not mutable, needs a copy.
-            matrix_task = dict(alias=alias_default, env=task.get("env").copy())
+            matrix_task = dict(alias=alias_default, env=task.get("env", dict()).copy())
             matrix_name = item.get("name", name_default)
             CirrusCfg._working = matrix_name
 

cirrus-ci_env/test/test_cirrus-ci_env.py

@@ -165,6 +165,19 @@ def test_simple_render(self):
         result = self.CCfg(config).tasks
         self.assertDictEqual(result, expected)
 
+    def test_noenv_render(self):
+        """Verify rendering of task w/o local env. vars."""
+        task = dict(something="ignored")
+        config = dict(env=self.global_env, test_task=task)
+        expected = {
+            "test": {
+                "alias": "test",
+                "env": {}
+            }
+        }
+        result = self.CCfg(config).tasks
+        self.assertDictEqual(result, expected)
+
     def test_simple_matrix(self):
         """Verify unrolling of a simple matrix containing two tasks."""
         matrix1 = dict(name="test_matrix1", env=dict(item="${foo}bar"))
@@ -194,6 +207,22 @@ def test_simple_matrix(self):
             self.assertDictEqual(expected[task_name], result[task_name])
         self.assertDictEqual(result, expected)
 
+    def test_noenv_matrix(self):
+        """Verify unrolling of single matrix w/o env. vars."""
+        matrix = dict(name="test_matrix")
+        task = dict(env=dict(something="untouched"), matrix=[matrix])
+        config = dict(env=self.global_env, test_task=task)
+        expected = {
+            "test_matrix": {
+                "alias": "test",
+                "env": {
+                    "something": "untouched"
+                }
+            }
+        }
+        result = self.CCfg(config).tasks
+        self.assertDictEqual(result, expected)
+
     def test_rendered_name_matrix(self):
         """Verify env. values may be used in matrix names with spaces."""
         test_foobar = dict(env=dict(item="$foo$bar", unique="item"))