updates to service dependency resolution to allow for multithreaded startup, also improved tests to validate service boot ordering for expected outcomes

daemon/tests/test_services.py

@@ -220,7 +220,7 @@ class TestServices:
         assert default_service == my_service
         assert custom_service and custom_service != my_service
 
-    def test_services_dependencies(self):
+    def test_services_dependency(self):
         # given
         service_a = CoreService()
         service_a.name = "a"
@@ -238,20 +238,34 @@ class TestServices:
         service_d.dependencies = ()
         service_e.dependencies = ()
         services = [service_a, service_b, service_c, service_d, service_e]
+        expected1 = {service_a.name, service_b.name, service_c.name, service_d.name}
+        expected2 = [service_e]
 
         # when
-        results = []
         permutations = itertools.permutations(services)
         for permutation in permutations:
             permutation = list(permutation)
-            result = ServiceDependencies(permutation).boot_order()
-            results.append(result)
+            results = ServiceDependencies(permutation).boot_order()
+            # then
+            for result in results:
+                result_set = {x.name for x in result}
+                if len(result) == 4:
+                    a_index = result.index(service_a)
+                    b_index = result.index(service_b)
+                    c_index = result.index(service_c)
+                    d_index = result.index(service_d)
+                    assert b_index < a_index
+                    assert b_index < c_index
+                    assert d_index < c_index
+                    assert result_set == expected1
+                elif len(result) == 1:
+                    assert expected2 == result
+                else:
+                    raise ValueError(
+                        f"unexpected result: {results}, perm({permutation})"
+                    )
 
-        # then
-        for result in results:
-            assert len(result) == len(services)
-
-    def test_services_missing_dependency(self):
+    def test_services_dependency_missing(self):
         # given
         service_a = CoreService()
         service_a.name = "a"
@@ -271,7 +285,7 @@ class TestServices:
             with pytest.raises(ValueError):
                 ServiceDependencies(permutation).boot_order()
 
-    def test_services_dependencies_cycle(self):
+    def test_services_dependency_cycle(self):
         # given
         service_a = CoreService()
         service_a.name = "a"
@@ -291,7 +305,7 @@ class TestServices:
             with pytest.raises(ValueError):
                 ServiceDependencies(permutation).boot_order()
 
-    def test_services_common_dependency(self):
+    def test_services_dependency_common(self):
         # given
         service_a = CoreService()
         service_a.name = "a"
@@ -299,18 +313,64 @@ class TestServices:
         service_b.name = "b"
         service_c = CoreService()
         service_c.name = "c"
-        service_b.dependencies = (service_a.name,)
-        service_c.dependencies = (service_a.name, service_b.name)
-        services = [service_a, service_b, service_c]
+        service_d = CoreService()
+        service_d.name = "d"
+        service_a.dependencies = (service_b.name,)
+        service_c.dependencies = (service_d.name, service_b.name)
+        services = [service_a, service_b, service_c, service_d]
+        expected = {service_a.name, service_b.name, service_c.name, service_d.name}
 
         # when
-        results = []
         permutations = itertools.permutations(services)
         for permutation in permutations:
             permutation = list(permutation)
-            result = ServiceDependencies(permutation).boot_order()
-            results.append(result)
+            results = ServiceDependencies(permutation).boot_order()
 
-        # then
-        for result in results:
-            assert result == [service_a, service_b, service_c]
+            # then
+            for result in results:
+                assert len(result) == 4
+                result_set = {x.name for x in result}
+                a_index = result.index(service_a)
+                b_index = result.index(service_b)
+                c_index = result.index(service_c)
+                d_index = result.index(service_d)
+                assert b_index < a_index
+                assert d_index < c_index
+                assert b_index < c_index
+                assert expected == result_set
+
+    def test_services_dependency_common2(self):
+        # given
+        service_a = CoreService()
+        service_a.name = "a"
+        service_b = CoreService()
+        service_b.name = "b"
+        service_c = CoreService()
+        service_c.name = "c"
+        service_d = CoreService()
+        service_d.name = "d"
+        service_a.dependencies = (service_b.name,)
+        service_b.dependencies = (service_c.name, service_d.name)
+        service_c.dependencies = (service_d.name,)
+        services = [service_a, service_b, service_c, service_d]
+        expected = {service_a.name, service_b.name, service_c.name, service_d.name}
+
+        # when
+        permutations = itertools.permutations(services)
+        for permutation in permutations:
+            permutation = list(permutation)
+            results = ServiceDependencies(permutation).boot_order()
+
+            # then
+            for result in results:
+                assert len(result) == 4
+                result_set = {x.name for x in result}
+                a_index = result.index(service_a)
+                b_index = result.index(service_b)
+                c_index = result.index(service_c)
+                d_index = result.index(service_d)
+                assert b_index < a_index
+                assert c_index < b_index
+                assert d_index < b_index
+                assert d_index < c_index
+                assert expected == result_set