Merge pull request #465 from terminusdb/select-with-no-variables

Select with no variables

Author: hoijnet

terminusdb_client/tests/integration_tests/test_woql_select_empty.py

@@ -0,0 +1,239 @@
+"""
+Integration tests for WOQL select() with empty variable list
+
+Tests that select() with no arguments is valid and works correctly.
+This is needed for patterns like localize() where we want to hide
+all inner variables while still executing the inner query.
+"""
+
+import pytest
+
+from terminusdb_client import Client
+from terminusdb_client.woqlquery.woql_query import WOQLQuery
+
+
+@pytest.fixture(scope="module")
+def select_empty_db(docker_url):
+    """Create a client and test database for select empty tests."""
+    client = Client(docker_url)
+    client.connect()
+
+    db_name = "db__test_select_empty"
+
+    # Create test database if it doesn't exist
+    if db_name not in client.list_databases():
+        client.create_database(db_name)
+    else:
+        client.connect(db=db_name)
+
+    yield client
+
+    # Cleanup
+    try:
+        client.delete_database(db_name, "admin")
+    except Exception:
+        pass
+
+
+class TestWOQLSelectEmpty:
+    """Integration tests for WOQL select() with empty variable list."""
+
+    @pytest.fixture(autouse=True)
+    def setup(self, select_empty_db):
+        """Setup client reference for each test."""
+        self.client = select_empty_db
+
+    def test_select_no_args_returns_empty_bindings(self):
+        """select() with no arguments should be valid and return empty bindings."""
+        # select() with no arguments should:
+        # 1. Be valid syntax (not throw client-side error)
+        # 2. Execute successfully on server
+        # 3. Return bindings with no variables (empty dicts)
+
+        query = WOQLQuery().select(WOQLQuery().eq("v:X", WOQLQuery().string("test")))
+
+        result = self.client.query(query)
+
+        assert result is not None
+        assert "bindings" in result
+        assert len(result["bindings"]) == 1
+
+        # The binding should be empty since select() hides all variables
+        binding = result["bindings"][0]
+        assert len(binding) == 0
+
+    def test_select_hides_inner_variables_outer_visible(self):
+        """select() should hide inner variables while outer variables remain visible."""
+        # Pattern: outer variable is visible, inner variables are hidden by select()
+        query = WOQLQuery().woql_and(
+            WOQLQuery().eq("v:Outer", WOQLQuery().string("visible")),
+            WOQLQuery().select(
+                WOQLQuery().woql_and(
+                    WOQLQuery().eq("v:Inner", WOQLQuery().string("hidden")),
+                    # Use both variables to ensure query executes
+                    WOQLQuery().eq("v:Both", "v:Inner"),
+                )
+            ),
+        )
+
+        result = self.client.query(query)
+
+        assert result is not None
+        assert "bindings" in result
+        assert len(result["bindings"]) == 1
+
+        binding = result["bindings"][0]
+
+        # v:Outer should be visible (defined outside select())
+        outer = binding.get("Outer") or binding.get("v:Outer")
+        assert outer is not None
+        assert outer.get("@value") == "visible"
+
+        # v:Inner and v:Both should NOT be visible (inside select())
+        assert binding.get("Inner") is None
+        assert binding.get("v:Inner") is None
+        assert binding.get("Both") is None
+        assert binding.get("v:Both") is None
+
+    def test_select_allows_outer_binding_through_unification(self):
+        """select() should hide inner variables but allow outer variables to be bound."""
+        # Pattern: outer variable is visible and gets value through unification
+        query = WOQLQuery().woql_and(
+            WOQLQuery().eq("v:Outer", "v:Outer"),
+            WOQLQuery().select(
+                WOQLQuery().woql_and(
+                    WOQLQuery().eq("v:Inner", WOQLQuery().string("hidden")),
+                    WOQLQuery().eq(
+                        "v:Inner_Shared_Value", WOQLQuery().string("visible")
+                    ),
+                    # Use both variables to ensure query executes
+                    WOQLQuery().eq("v:Outer", "v:Inner_Shared_Value"),
+                )
+            ),
+        )
+
+        result = self.client.query(query)
+
+        assert result is not None
+        assert "bindings" in result
+        assert len(result["bindings"]) == 1
+
+        binding = result["bindings"][0]
+
+        # v:Outer should be visible (defined outside select())
+        outer = binding.get("Outer") or binding.get("v:Outer")
+        assert outer is not None
+        assert outer.get("@value") == "visible"
+
+        # v:Inner should NOT be visible (inside select())
+        assert binding.get("Inner") is None
+        assert binding.get("v:Inner") is None
+
+    def test_select_generated_json_has_empty_variables_array(self):
+        """select() with no variables should generate JSON with empty variables array."""
+        # Verify the WOQL builder generates correct JSON with empty variables array
+        query = WOQLQuery().select(WOQLQuery().eq("v:X", WOQLQuery().string("test")))
+
+        json_query = query.to_dict()
+
+        assert json_query["@type"] == "Select"
+        assert "variables" in json_query
+        assert isinstance(json_query["variables"], list)
+        assert len(json_query["variables"]) == 0
+
+    def test_two_localized_blocks_bind_same_variable_name_different_values(self):
+        """Two localized blocks can bind same variable name to different values."""
+        # KEY TEST: Demonstrates select() scope isolation
+        # Two separate localized blocks use the same internal variable name (v:temp)
+        # but bind it to different values - proving they don't interfere
+
+        localized1, v1 = WOQLQuery().localize(
+            {
+                "result": "v:result1",
+                "temp": None,  # local variable - same name in both blocks
+            }
+        )
+
+        localized2, v2 = WOQLQuery().localize(
+            {
+                "result": "v:result2",
+                "temp": None,  # local variable - same name, different scope
+            }
+        )
+
+        query = WOQLQuery().woql_and(
+            # First localized block: temp = "first", result1 = temp
+            localized1(
+                WOQLQuery().woql_and(
+                    WOQLQuery().eq(v1.temp, WOQLQuery().string("first")),
+                    WOQLQuery().eq(v1.result, v1.temp),
+                )
+            ),
+            # Second localized block: temp = "second", result2 = temp
+            localized2(
+                WOQLQuery().woql_and(
+                    WOQLQuery().eq(v2.temp, WOQLQuery().string("second")),
+                    WOQLQuery().eq(v2.result, v2.temp),
+                )
+            ),
+        )
+
+        result = self.client.query(query)
+
+        assert result is not None
+        assert "bindings" in result
+        assert len(result["bindings"]) == 1
+
+        binding = result["bindings"][0]
+
+        # v:result1 should be "first" (from first localized block)
+        result1 = binding.get("result1") or binding.get("v:result1")
+        assert result1 is not None
+        assert result1.get("@value") == "first"
+
+        # v:result2 should be "second" (from second localized block)
+        result2 = binding.get("result2") or binding.get("v:result2")
+        assert result2 is not None
+        assert result2.get("@value") == "second"
+
+        # The temp variables should NOT be visible (they're local)
+        assert binding.get("temp") is None
+        assert binding.get("v:temp") is None
+
+    def test_localize_pattern_hides_local_exposes_outer(self):
+        """localize pattern: select() hides local variables, eq() exposes outer params."""
+        # This is the real use case: localize() pattern
+        # - Outer parameters are bound via eq() OUTSIDE select()
+        # - Local variables are hidden by select()
+
+        # Simulate what localize() should do with select() (not select(''))
+        outer_param = "v:param_unique_123"
+        local_var = "v:local_unique_456"
+
+        query = WOQLQuery().woql_and(
+            # Outer eq() bindings - these should be visible
+            WOQLQuery().eq("v:MyParam", outer_param),
+            # select() with no args - hides everything inside
+            WOQLQuery().select(
+                WOQLQuery().woql_and(
+                    # Bind the unique param to a value
+                    WOQLQuery().eq(outer_param, WOQLQuery().string("param_value")),
+                    # Use a local variable (should be hidden)
+                    WOQLQuery().eq(local_var, WOQLQuery().string("local_value")),
+                )
+            ),
+        )
+
+        result = self.client.query(query)
+
+        assert result is not None
+        assert "bindings" in result
+        assert len(result["bindings"]) == 1
+
+        binding = result["bindings"][0]
+
+        # v:MyParam should be visible (eq() is outside select())
+        # and unified with outer_param which was bound inside
+        my_param = binding.get("MyParam") or binding.get("v:MyParam")
+        assert my_param is not None
+        assert my_param.get("@value") == "param_value"