Feat/environment variables in workflow (#6515)

Co-authored-by: JzoNg <jzongcode@gmail.com>

api/tests/unit_tests/app/test_segment.py

@@ -0,0 +1,53 @@
+from core.app.segments import SecretVariable, parser
+from core.helper import encrypter
+from core.workflow.entities.node_entities import SystemVariable
+from core.workflow.entities.variable_pool import VariablePool
+
+
+def test_segment_group_to_text():
+    variable_pool = VariablePool(
+        system_variables={
+            SystemVariable('user_id'): 'fake-user-id',
+        },
+        user_inputs={},
+        environment_variables=[
+            SecretVariable(name='secret_key', value='fake-secret-key'),
+        ],
+    )
+    variable_pool.add(('node_id', 'custom_query'), 'fake-user-query')
+    template = (
+        'Hello, {{#sys.user_id#}}! Your query is {{#node_id.custom_query#}}. And your key is {{#env.secret_key#}}.'
+    )
+    segments_group = parser.convert_template(template=template, variable_pool=variable_pool)
+
+    assert segments_group.text == 'Hello, fake-user-id! Your query is fake-user-query. And your key is fake-secret-key.'
+    assert (
+        segments_group.log
+        == f"Hello, fake-user-id! Your query is fake-user-query. And your key is {encrypter.obfuscated_token('fake-secret-key')}."
+    )
+
+
+def test_convert_constant_to_segment_group():
+    variable_pool = VariablePool(
+        system_variables={},
+        user_inputs={},
+        environment_variables=[],
+    )
+    template = 'Hello, world!'
+    segments_group = parser.convert_template(template=template, variable_pool=variable_pool)
+    assert segments_group.text == 'Hello, world!'
+    assert segments_group.log == 'Hello, world!'
+
+
+def test_convert_variable_to_segment_group():
+    variable_pool = VariablePool(
+        system_variables={
+            SystemVariable('user_id'): 'fake-user-id',
+        },
+        user_inputs={},
+        environment_variables=[],
+    )
+    template = '{{#sys.user_id#}}'
+    segments_group = parser.convert_template(template=template, variable_pool=variable_pool)
+    assert segments_group.text == 'fake-user-id'
+    assert segments_group.log == 'fake-user-id'