[teamd]: Fix Jinja2 template for calculating min_ports (#791)

In Jinja2, '|' cannot be treated directly as piping operator. The
operator precedence of '|' is higher than '*'. The filter only applies
to the value just before it. Group the expression to make sure that the
filter is applied to the outcome of the expression.

Update the unit test to add such case.

dockers/docker-teamd/teamd.j2

@@ -5,7 +5,7 @@
         "name": "lacp",
         "active": true,
 {# Use 75% links upperbound as min-links #}
-        "min_ports": {{ minigraph_portchannels[pc]['members'] | length * 0.75 | round(0, 'ceil') | int}},
+        "min_ports": {{ (minigraph_portchannels[pc]['members'] | length * 0.75) | round(0, 'ceil') | int }},
         "tx_hash": ["eth", "ipv4", "ipv6"]
     },
     "link_watch": {
@@ -13,7 +13,7 @@
     },
     "ports": {
 {% for member in minigraph_portchannels[pc]['members'] %}
-        "{{member}}": {}{% if not loop.last %},{% endif %}
+        "{{ member }}": {}{% if not loop.last %},{% endif %}
 
 {% endfor %}
     }

src/sonic-config-engine/tests/sample_output/pc_sample_output/PortChannel01.conf

@@ -0,0 +1,20 @@
+{
+    "device": "PortChannel01",
+    "hwaddr": "e4:1d:2d:a5:f3:ad",
+    "runner": {
+        "name": "lacp",
+        "active": true,
+        "min_ports": 3,
+        "tx_hash": ["eth", "ipv4", "ipv6"]
+    },
+    "link_watch": {
+        "name": "ethtool"
+    },
+    "ports": {
+        "Ethernet112": {},
+        "Ethernet116": {},
+        "Ethernet120": {},
+        "Ethernet124": {}
+    }
+}
+

src/sonic-config-engine/tests/test_j2files.py

@@ -10,6 +10,7 @@ class TestJ2Files(TestCase):
         self.test_dir = os.path.dirname(os.path.realpath(__file__))
         self.script_file = os.path.join(self.test_dir, '..', 'sonic-cfggen')
         self.t0_minigraph = os.path.join(self.test_dir, 't0-sample-graph.xml')
+        self.pc_minigraph = os.path.join(self.test_dir, 'pc-test-graph.xml')
         self.t0_port_config = os.path.join(self.test_dir, 't0-sample-port-config.ini')
         self.output_file = os.path.join(self.test_dir, 'output')
 
@@ -30,21 +31,33 @@ class TestJ2Files(TestCase):
         self.assertEqual(data["Ethernet4"], "fortyGigE0/4")        
         
     def test_teamd(self):
+
+        def test_render_teamd(self, pc, minigraph, sample_output):
+            teamd_file = os.path.join(self.test_dir, '..', '..', '..', 'dockers', 'docker-teamd', 'teamd.j2')
+            argument = '-m ' + minigraph + ' -p ' + self.t0_port_config + ' -a \'{\"pc\":\"' + pc + '\",\"hwaddr\":\"e4:1d:2d:a5:f3:ad\"}\' -t ' + teamd_file + ' > ' + self.output_file
+            self.run_script(argument)
+            self.assertTrue(filecmp.cmp(sample_output, self.output_file))
+
+        # Test T0 minigraph
         argument = '-m ' + self.t0_minigraph + ' -p ' + self.t0_port_config + ' -v "minigraph_portchannels.keys() | join(\' \')"'
         output = self.run_script(argument) # Mock the output via config.sh in docker-teamd
         pc_list = output.split()
 
-        def test_render_teamd(self, pc):
-            teamd_file = os.path.join(self.test_dir, '..', '..', '..', 'dockers', 'docker-teamd', 'teamd.j2')
-            sample_output_file = os.path.join(self.test_dir, 'sample_output',pc + '.conf')
-            argument = '-m ' + self.t0_minigraph + ' -p ' + self.t0_port_config + ' -a \'{\"pc\":\"' + pc + '\",\"hwaddr\":\"e4:1d:2d:a5:f3:ad\"}\' -t ' + teamd_file + ' > ' + self.output_file
-            self.run_script(argument)
-            assert filecmp.cmp(sample_output_file, self.output_file)
-
         for i in range(1, 5):
             pc_name = 'PortChannel0' + str(i)
-            assert pc_name in pc_list
-            test_render_teamd(self, pc_name)
+            self.assertTrue(pc_name in pc_list)
+            sample_output = os.path.join(self.test_dir, 'sample_output', 't0_sample_output', pc_name + '.conf')
+            test_render_teamd(self, pc_name, self.t0_minigraph, sample_output)
+
+        # Test port channel test minigraph
+        argument = '-m ' + self.pc_minigraph + ' -p ' + self.t0_port_config + ' -v "minigraph_portchannels.keys() | join(\' \')"'
+        output = self.run_script(argument) # Mock the output via config.sh in docker-teamd
+        pc_list = output.split()
+
+        pc_name = 'PortChannel01'
+        self.assertTrue(pc_name in pc_list)
+        sample_output = os.path.join(self.test_dir, 'sample_output', 'pc_sample_output', pc_name + '.conf')
+        test_render_teamd(self, pc_name, self.pc_minigraph, sample_output)
 
     def test_ipinip(self):
         ipinip_file = os.path.join(self.test_dir, '..', '..', '..', 'dockers', 'docker-orchagent', 'ipinip.json.j2')