# PropSchema
[](https://hex.pm/packages/prop_schema)
[](/projects/321150)
An extension of both `Ecto.Schema` and `ExUnitProperties` for auto-generation of changeset property tests.
Consists of two main modules: `PropSchema` and `PropSchema.TestHarness`
## Usage
#### Look at the documentation for full usage
https://hexdocs.com/prop_schema
#### Basic Example
In example_module.ex:
```elixir
defmodule ExampleModule do
use PropSchema
alias Ecto.Changeset
prop_schema "example" do
prop_field(:example_string, :string, string_type: :alphanumeric, required: true)
prop_field(:example_int, :integer, positive: true, required: false)
field(:example_float, :float)
end
def changeset(schema, data) do
schema
|> Changeset.cast(data, [:example_string, :example_int, :example_float])
|> Changeset.validate_required([:example_string])
end
end
```
In example_module_test.ex:
```elixir
defmodule ExampleModuleTest do
use PropSchema.TestHarness, to_test: PropSchema.ExampleModule
end
```
Then run `mix test`. In this example it will make 3 prop tests.
Or for a more realistic example see example [module](https://github.com/podium/prop_schema/blob/master/lib/prop_schema/examples/animagus/csv_mapping.ex), [properties](https://github.com/podium/prop_schema/blob/master/lib/prop_schema/examples/animagus/csv_mapping_properties.ex), and [generated tests](https://github.com/podium/prop_schema/blob/master/lib/prop_schema/examples/animagus/results_of_print.ex).
## Tips for First Time Users
I would suggest following this 6 step process your first time through (to get a feel for how this library builds on `Ecto.Schema` and `StreamData` to generate dummy data and tests)
1. Start with simply creating your `Ecto.Schema` and define your changeset requirements as you would normally do.
2. Modify that schema by replacing all the macros with the corresponding `PropSchema` macros (Don't worry about adding any options at this point)
3. Create a `.iex.mix` file where you define a module that
1. Uses `PropSchema.Stream.generate_complete_map/2` with your new schema's module as its first argument and
2. Defines a public function that runs `complete() |> Enum.at(0)` (This will generate a random map that you can run through your changeset)
4. Determine what is unsatisfactory with the resulting map and add `generate_prop/3` functions to a new "AdditionalProperties" module for each key of that map you'd like to generate (see `PropSchema.AdditionalProperties` for directions, or examine this: [example](https://github.com/podium/prop_schema/blob/master/lib/prop_schema/examples/animagus/csv_mapping_properties.ex))
5. Place this new module as the second argument of the `PropSchema.Stream.generate_complete_map/2` call in your `.iex.exs` file.
6. Once the generated map is satisfactory, use the `PropSchema.TestHarness` module to generate your tests with ease.
