synchronal / schema_assertions

ExUnit assertions for Ecto schemas

SchemaAssertions

ExUnit assertions for Ecto schemas.

Work in progress.

Installation

If available in Hex, the package can be installed by adding schema_assertions to your list of dependencies in mix.exs:

def deps do
  [
    {:schema_assertions, "~> 0.1"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/schema_assertions.

Other useful schema-related libraries

• excellent_migrations

License

This code is available under the Apache 2.0 license. See also license. Based on code from Epi Viewpoint.

schema_assertions's Issues

assert_belongs_to should verify that the column exists

When removing an association, assert_belongs_to will still pass if the association has not been deleted from a schema.

There might be checks we can do for the other association assertions as well.

doesn't allow asserting belongs to with custom source

Given a schema:

defmodule Group do
  schema "groups" do
    belongs_to :org, Org, source: :organization_id
  end
end

The following test will fail:

test "schema" do
  assert_belongs_to Group, :org, Org
end

...with the message:

 Expected Group to belong to
   :org
 via
   .Org

 org_id does not exist in table

This is true that org_id is not a field. It's an alias for organization_id, but it would be nice if I could specify a source in the assertion.

---

I did some sleuthing and looked at the schema reflection and saw that the :owner_key is set to :org_id by Ecto. It doesn't seem like a bug because everything works as you would expect in the actual code.

However that reflection doesn't give us access to the source. I did find the reflection :field_source which looks something like:

Group.__schema__(:field_source, :org_id) # returns :organization_id

Checking the reflection of the field source for :org_id gives us the value :organization_id which is exactly what we're looking for. I wonder if we could leverage this in connection with an optional :source option in the assert_belongs_to call such that when it is provided we check for a field source alias here:

schema_assertions/lib/schema_assertions/schema.ex

Lines 9 to 14 in a4c8f2d

	%Ecto.Association.BelongsTo{queryable: ^assoc_module, owner_key: owner_key} ->
	fieldset = module.__schema__(:source) |> SchemaAssertions.Database.fieldset()
	if Keyword.has_key?(fieldset, owner_key),
	do: :ok,
	else: {:error, "#{owner_key} does not exist in table"}

What do y'all think? If you like this idea, I can open a PR for it.

does not assert that fields are actually defined in the schema

It checks that the fields listed in assert_schema are in the database, but doesn't fail if some/all of them are not defined in the schema module.