diff --git a/test/Table_Tests/src/Common_Table_Operations/Cast_Spec.enso b/test/Table_Tests/src/Common_Table_Operations/Cast_Spec.enso
index a6f4da589f948..c33f840e4bc1a 100644
--- a/test/Table_Tests/src/Common_Table_Operations/Cast_Spec.enso
+++ b/test/Table_Tests/src/Common_Table_Operations/Cast_Spec.enso
@@ -77,7 +77,7 @@ spec setup =
             c4.to_vector . should_equal [Nothing, 1001, 1000, 1001]
 
     Test.group prefix+"Table.cast" pending=(if setup.is_database.not then "Cast is not implemented in the in-memory backend yet.") <|
-        Test.specify "should cast the columns in-place and not reorder them" <|
+        Test.specify 'should cast the columns "in-place" and not reorder them' <|
             t = table_builder [["X", [1, 2, 3000]], ["Y", [4, 5, 6]], ["Z", [7, 8, 9]], ["A", [True, False, True]]]
             t2 = t.cast ["Z", "Y"] Value_Type.Char
             t2.column_names . should_equal ["X", "Y", "Z", "A"]
diff --git a/test/Table_Tests/src/Common_Table_Operations/Join/Union_Spec.enso b/test/Table_Tests/src/Common_Table_Operations/Join/Union_Spec.enso
index 28293b8e6b77d..8d421755b4f8d 100644
--- a/test/Table_Tests/src/Common_Table_Operations/Join/Union_Spec.enso
+++ b/test/Table_Tests/src/Common_Table_Operations/Join/Union_Spec.enso
@@ -193,8 +193,18 @@ spec setup =
             check_same <| t1.union [] keep_unmatched_columns=True
             check_same <| t1.union [] match_columns=Match_Columns.By_Position keep_unmatched_columns=True
 
-        # TODO tests for merging varchar (currently not possible in in-memory, so Postgres only)
-        # TODO unit tests for `find_common_type` helper
+        Test.specify "should correctly unify text columns of various lengths" pending=(if setup.test_selection.fixed_length_text_columns.not then "Fixed-length Char columns are not supported by this backend.") <|
+            t1 = table_builder [["A", ["a", "b", "c"]]] . cast "A" (Value_Type.Char size=1 variable_length=False)
+            t2 = table_builder [["A", ["xyz", "abc", "def"]]] . cast "A" (Value_Type.Char size=3 variable_length=False)
+
+            t1.at "A" . value_type . should_equal (Value_Type.Char size=1 variable_length=False)
+            t2.at "A" . value_type . should_equal (Value_Type.Char size=3 variable_length=False)
+
+            t3 = t1.union t2
+            expect_column_names ["A"] t3
+            t3.at "A" . to_vector . should_equal ["a", "b", "c", "xyz", "abc", "def"]
+            t3.at "A" . value_type . is_text . should_be_true
+            t3.at "A" . value_type . variable_length . should_be_true
 
         Test.specify "should find a common type that will fit the merged columns" <|
             t1 = table_builder [["int+bool", [1, 2, 3]], ["int+float", [0, 1, 2]]]
diff --git a/test/Table_Tests/src/Helpers/Value_Type_Spec.enso b/test/Table_Tests/src/Helpers/Value_Type_Spec.enso
index 7800547696d17..e21101bba6e58 100644
--- a/test/Table_Tests/src/Helpers/Value_Type_Spec.enso
+++ b/test/Table_Tests/src/Helpers/Value_Type_Spec.enso
@@ -2,6 +2,7 @@ from Standard.Base import all
 
 import Standard.Table.Data.Type.Value_Type.Bits
 import Standard.Table.Data.Type.Value_Type.Value_Type
+import Standard.Table.Data.Type.Value_Type_Helpers
 
 from Standard.Test import Test, Test_Suite
 import Standard.Test.Extensions
@@ -27,4 +28,38 @@ spec =
             Value_Type.Unsupported_Data_Type.to_display_text . should_equal "Unsupported_Data_Type"
             (Value_Type.Unsupported_Data_Type "FOO-BAR").to_display_text . should_equal "Unsupported_Data_Type (FOO-BAR)"
 
+        Test.specify "should use correct in-memory logic to reconcile pairs of types for operations like union/iif" <|
+            Value_Type_Helpers.reconcile_types Value_Type.Boolean Value_Type.Boolean . should_equal Value_Type.Boolean
+            Value_Type_Helpers.reconcile_types Value_Type.Boolean Value_Type.Integer . should_equal Value_Type.Integer
+
+            Value_Type_Helpers.reconcile_types (Value_Type.Integer Bits.Bits_16) (Value_Type.Integer Bits.Bits_32) . should_equal (Value_Type.Integer Bits.Bits_32)
+            Value_Type_Helpers.reconcile_types (Value_Type.Float Bits.Bits_32) (Value_Type.Float Bits.Bits_32) . should_equal (Value_Type.Float Bits.Bits_32)
+            Value_Type_Helpers.reconcile_types (Value_Type.Float Bits.Bits_32) (Value_Type.Float Bits.Bits_64) . should_equal (Value_Type.Float Bits.Bits_64)
+
+            Value_Type_Helpers.reconcile_types Value_Type.Boolean Value_Type.Byte . should_equal Value_Type.Byte
+            Value_Type_Helpers.reconcile_types (Value_Type.Integer Bits.Bits_16) Value_Type.Byte . should_equal (Value_Type.Integer Bits.Bits_16)
+            # 64-bit floats are always used when unifying with integers
+            Value_Type_Helpers.reconcile_types (Value_Type.Float Bits.Bits_32) Value_Type.Byte . should_equal Value_Type.Float
+            Value_Type_Helpers.reconcile_types (Value_Type.Float Bits.Bits_32) Value_Type.Boolean . should_equal Value_Type.Float
+
+            Value_Type_Helpers.reconcile_types (Value_Type.Char 10 False) (Value_Type.Char 10 False) . should_equal (Value_Type.Char 10 False)
+            Value_Type_Helpers.reconcile_types (Value_Type.Char 10 False) (Value_Type.Char 10 True) . should_equal (Value_Type.Char 10 True)
+            Value_Type_Helpers.reconcile_types (Value_Type.Char 100 False) (Value_Type.Char 10 True) . should_equal (Value_Type.Char 100 True)
+            Value_Type_Helpers.reconcile_types (Value_Type.Char 10 False) (Value_Type.Char 15 False) . should_equal (Value_Type.Char 15 True)
+
+            Value_Type_Helpers.reconcile_types Value_Type.Date Value_Type.Date . should_equal Value_Type.Date
+            Value_Type_Helpers.reconcile_types Value_Type.Time Value_Type.Time . should_equal Value_Type.Time
+            Value_Type_Helpers.reconcile_types Value_Type.Date_Time Value_Type.Date_Time . should_equal Value_Type.Date_Time
+            ## Mixing date and time leads to mixed, if the user wants to convert date to at-midnight timestamp or
+               date-time to just date, they need to do it explicitly.
+            Value_Type_Helpers.reconcile_types Value_Type.Date Value_Type.Date_Time . should_equal Value_Type.Mixed
+            Value_Type_Helpers.reconcile_types Value_Type.Time Value_Type.Date_Time . should_equal Value_Type.Mixed
+
+            Value_Type_Helpers.reconcile_types Value_Type.Float Value_Type.Integer . should_equal Value_Type.Float
+            Value_Type_Helpers.reconcile_types Value_Type.Char Value_Type.Integer . should_equal Value_Type.Mixed
+            Value_Type_Helpers.reconcile_types Value_Type.Float Value_Type.Char . should_equal Value_Type.Mixed
+            Value_Type_Helpers.reconcile_types Value_Type.Float Value_Type.Binary . should_equal Value_Type.Mixed
+            Value_Type_Helpers.reconcile_types Value_Type.Char Value_Type.Binary . should_equal Value_Type.Mixed
+            Value_Type_Helpers.reconcile_types Value_Type.Char Value_Type.Boolean . should_equal Value_Type.Mixed
+
 main = Test_Suite.run_main spec