1 files changed, 79 insertions, 0 deletions
diff --git a/spec/support/helpers/table_schema_helpers.rb b/spec/support/helpers/table_schema_helpers.rb
new file mode 100644
index 00000000000..39f783caa0a
--- /dev/null
+++ b/spec/support/helpers/table_schema_helpers.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+module TableSchemaHelpers
+  def connection
+    ActiveRecord::Base.connection
+  end
+
+  def expect_table_to_be_replaced(original_table:, replacement_table:, archived_table:)
+    original_oid = table_oid(original_table)
+    replacement_oid = table_oid(replacement_table)
+
+    yield
+
+    expect(table_oid(original_table)).to eq(replacement_oid)
+    expect(table_oid(archived_table)).to eq(original_oid)
+    expect(table_oid(replacement_table)).to be_nil
+  end
+
+  def table_oid(name)
+    connection.select_value(<<~SQL)
+      SELECT oid
+      FROM pg_catalog.pg_class
+      WHERE relname = '#{name}'
+    SQL
+  end
+
+  def table_type(name)
+    connection.select_value(<<~SQL)
+      SELECT
+        CASE class.relkind
+        WHEN 'r' THEN 'normal'
+        WHEN 'p' THEN 'partitioned'
+        ELSE 'other'
+        END as table_type
+      FROM pg_catalog.pg_class class
+      WHERE class.relname = '#{name}'
+    SQL
+  end
+
+  def sequence_owned_by(table_name, column_name)
+    connection.select_value(<<~SQL)
+      SELECT
+        sequence.relname as name
+      FROM pg_catalog.pg_class as sequence
+      INNER JOIN pg_catalog.pg_depend depend
+        ON depend.objid = sequence.relfilenode
+      INNER JOIN pg_catalog.pg_class class
+        ON class.relfilenode = depend.refobjid
+      INNER JOIN pg_catalog.pg_attribute attribute
+        ON attribute.attnum = depend.refobjsubid
+        AND attribute.attrelid = depend.refobjid
+      WHERE class.relname = '#{table_name}'
+        AND attribute.attname = '#{column_name}'
+    SQL
+  end
+
+  def default_expression_for(table_name, column_name)
+    connection.select_value(<<~SQL)
+      SELECT
+        pg_get_expr(attrdef.adbin, attrdef.adrelid) AS default_value
+      FROM pg_catalog.pg_attribute attribute
+      INNER JOIN pg_catalog.pg_attrdef attrdef
+        ON attribute.attrelid = attrdef.adrelid
+        AND attribute.attnum = attrdef.adnum
+      WHERE attribute.attrelid = '#{table_name}'::regclass
+        AND attribute.attname = '#{column_name}'
+    SQL
+  end
+
+  def primary_key_constraint_name(table_name)
+    connection.select_value(<<~SQL)
+      SELECT
+        conname AS constraint_name
+      FROM pg_catalog.pg_constraint
+      WHERE conrelid = '#{table_name}'::regclass
+        AND contype = 'p'
+    SQL
+  end
+end