Updating unit tests for task manager refactoring

* Purging old task manager unit tests
* Migrating those tests to functional tests
* Updating fixtures and factories to support a change in the way the
  task manager is tested
* Fix an issue with the mk_credential fixture when used in functional
  tests. Previously it had trouble with multiplel invocations when
  persistence was used

awx/main/tests/functional/test_instances.py

@@ -0,0 +1,40 @@
+import pytest
+
+
+@pytest.mark.django_db
+def test_default_tower_instance_group(default_instance_group, job_factory):
+    assert default_instance_group in job_factory().preferred_instance_groups
+
+
+@pytest.mark.django_db
+def test_basic_instance_group_membership(instance_group_factory, default_instance_group, job_factory):
+    j = job_factory()
+    ig = instance_group_factory("basicA", [default_instance_group.instances.first()])
+    j.job_template.instance_groups.add(ig)
+    assert ig in j.preferred_instance_groups
+    assert default_instance_group not in j.preferred_instance_groups
+
+
+@pytest.mark.django_db
+def test_inherited_instance_group_membership(instance_group_factory, default_instance_group, job_factory, project, inventory):
+    j = job_factory()
+    j.project = project
+    j.inventory = inventory
+    ig_org = instance_group_factory("basicA", [default_instance_group.instances.first()])
+    ig_inv = instance_group_factory("basicB", [default_instance_group.instances.first()])
+    j.project.organization.instance_groups.add(ig_org)
+    j.inventory.instance_groups.add(ig_inv)
+    assert ig_org in j.preferred_instance_groups
+    assert ig_inv in j.preferred_instance_groups
+    assert default_instance_group not in j.preferred_instance_groups
+
+
+@pytest.mark.django_db
+def test_instance_group_capacity(instance_factory, instance_group_factory):
+    i1 = instance_factory("i1")
+    i2 = instance_factory("i2")
+    i3 = instance_factory("i3")
+    ig_all = instance_group_factory("all", instances=[i1, i2, i3])
+    assert ig_all.capacity == 300
+    ig_single = instance_group_factory("single", instances=[i1])
+    assert ig_single.capacity == 100