graphql-engine/server/tests-hspec/README.md

# tests-hspec

Graphql-engine integration tests written in Haskell using the [hspec](https://hspec.github.io) testing framework.

For motivation, rationale, and more, see the [test suite rfc](../../rfcs/hspec-test-suite.md).

**Table of Contents**

- [tests-hspec](#tests-hspec)
  - [Running the test suite](#running-the-test-suite)
  - [Test suite structure](#test-suite-structure)
    - [Harness](#harness)
    - [Test](#test)
  - [Adding a new test](#adding-a-new-test)
    - [Specifying contexts](#specifying-contexts)
      - [Make local state action](#make-local-state-action)
      - [Setup action](#setup-action)
      - [Teardown action](#teardown-action)
    - [Writing tests](#writing-tests)
  - [Style guide](#style-guide)
    - [Stick to Simple Haskell](#stick-to-simple-haskell)
    - [Write small, atomic, autonomous specs](#write-small-atomic-autonomous-specs)
    - [Use the `Harness.*` hierarchy for common functions](#use-the-harness-hierarchy-for-common-functions)

## Running the test suite

1. To run the Haskell integration test suite, we'll first need to start the backends:

   ```sh
   docker-compose up
   ```

   This will start up Postgres, SQL Server, Citus and MariaDB.


    > __Note__: on ARM64 architecture we'll need additional steps in order to test mssql properly.
    >
    > ### Preparation
    >
    > 1. Switch the docker image in `docker-compose/sqlserver/Dockerfile` to `azure-sql-edge`:
    >
    > ```diff
    > - FROM mcr.microsoft.com/mssql/server:2019-latest@sha256:a098c9ff6fbb8e1c9608ad7511fa42dba8d22e0d50b48302761717840ccc26af
    > + FROM mcr.microsoft.com/azure-sql-edge
    > ```
    >
    > 2. Install `sqlcmd` locally. On MacOS, this can be done with brew: `brew install mssql-tools`.
    >
    > ### Start the backends
    >
    > 1. Run `docker-compose up`
    > 2. Initialize the SQL Server database
    >
    >    ```sh
    >    (cd docker-compose/sqlserver && bash run-init.sh 65003)
    >    ```

2. Once the containers are up, you can run the test suite via

   ```sh
   cabal run tests-hspec
   ```

    You can also further refine which tests to run using the `-m` flag:

   ```sh
   cabal run tests-hspec -- -m "SQLServer"
   ```

    For additional information, consult the help section:

   ```sh
   cabal run tests-hspec -- --help
   ```

3. The local databases persist even after shutting down docker-compose.
   If this is undesirable, delete the databases using the following command:

   ```sh
   docker-compose down --volumes
   ```

## Test suite structure

### Harness

Modules under the [Harness/](Harness/) namespace provide the infrastructure
and supporting code for writing and running the tests.
It includes quasiquoters, interacting with backends, interfacing with HTTP,
constants, and so on.

Supporting code should be added under the `Harness.*` namespace instead of
added ad-hoc in test specs, to improve readability and reuse.

### Test

Modules under the [Test/](Test/) namespace define integration test specifications for various
features and backends.

## Adding a new test

The module [Test.HelloWorldSpec](Test/HelloWorldSpec.hs) contains a starting point
which can be built upon.

To create a new test:

1. Create a new module based on `Test.HelloWorldSpec`
2. Specify each relevant context on which the tests will run in `spec`
3. Specify the tests and expectations in `tests`

When creating a new test, make sure that:

1. The module name is suffixed by the word `Spec`
2. The module exports the entry point `spec :: SpecWith State`
3. The module is listed in the cabal file under `other-modules`

(1) and (2) are required for `hspec-discover` to find and run the test.

### Specifying contexts

We often want to run the same tests several times with slightly different
configuration. Most commonly, we want to assert that a given behaviour works
consistently across different backends.

[Harness.Test.Context](Harness/Test/Context.hs) defines two functions for
running test trees in terms of a list of `Context a`s.

Each `Context a` requires:
- a unique `name`, of type `ContextName`
- a `mkLocalState` action, of type `State -> IO a`
- a `setup` action, of type `(State, a) -> IO ()`
- a `teardown` action, of type `(State, a) -> IO ()`
- an `options` parameter, which will be threaded through the tests themselves
to modify behavior for a particular `Context`

Of these two functions, whether one wishes to use `Harness.Test.Context.run` or
`Harness.Test.Context.runWithLocalState` will depend on if their test can be
written in terms of information provided by the global `State` type or if it
depends on some additional "local" state.

More often than not, test authors should use `Harness.Test.Context.run`, which
is written in terms of `Context ()`. This uses `()` for the local test which
does not carry any "useful" state information, and is therefore omitted from
the body of the tests themselves.

In the rare cases where some local state is necessary (either for the test
itself, or as an argument to the `teardown` action for some `Context`), test
authors should use `Harness.Test.Context.runWithLocalState`. This function
takes a type parameter for its local state, which will be provided to both
the `teardown` action specified in `Context` as well as the body of tests
themselves.

#### Make local state action

This refers to the function `mkLocalState` defined for `Context`:

```hs
mkLocalState :: State -> IO a
```

Its return value, `IO a`, matches the `a` of `Context a`: it is the additional
local state that is required throughout the tests, in addition to the global
`State`. Some tests, such as tests which check remote relationships, need to keep some state which is local to the context,
but most tests do not need additional state, and define `mkLocalState` to be `Harness.Test.Context.noLocalState`.

This local state will be pass to the `setup` function and the `teardown` function.
The `teardown` function is responsible to destroy the local state as well, if needed.

#### Setup action

A setup action is a function of type `(State, a) -> IO ()` which is responsible for
creating the environment for the test. It needs to:

1. Clear and reconfigure the metadata
2. Setup tables and insert values
3. Track tables, add relationships, permissions

etc.

These actions can be created by running POST requests against graphql-engine
using `Harness.GraphqlEngine.post_`, or by running SQL requests against the
backend using `Backend.<backend>.run_`.

#### Teardown action

The teardown action is another function of type `(State, a) -> IO ()` which is
responsible for removing the environment created by the test or setup, so that
other tests can have a "clean slate" with no artifacts. The `(State, a)`
parameter is constructed from the `a` parameter of the `Context a`: it is the
local state that is passed throughout the tests.

This action is responsible for freeing acquired resources, and reverting all
local modifications: dropping newly created tables, deleting custom functions,
removing the changes made to the metadata, and so on.

These actions can be created by running POST requests against graphql-engine
using `Harness.GraphqlEngine.post_`, or by running SQL requests against the
backend using `Backend.<backend>.run_`.

### Writing tests

Test should be written (or reachable from) `tests :: SpecWith State`, or `tests
:: SpecWith (State, Foo)` for tests that use an additional local state.

A typical test will look similar to this:

```hs
  it "Where id=1" \state ->
    shouldReturnYaml
      ( GraphqlEngine.postGraphql
          state
          [graphql|
query {
  hasura_author(where: {id: {_eq: 1}}) {
    name
    id
  }
}
|]
      )
      [yaml|
data:
  hasura_author:
  - name: Author 1
    id: 1
|]
```

- `it` specifies the name of the test
- `shouldReturnYaml` creates an [`Expectation`](https://hspec.github.io/expectations.html)
  which does the following:
  - Runs a POST request against graphql-engine which can be specified using the `graphql` quasi-quoter.
  - Compares the response to an expected result which can be specified using the `yaml` quasi-quoter.

__Note__: these quasi-quoter can also perform string interpolation. See the relevant modules
under the [Harness.Quoter](Harness/Quoter) namespace.

## Style guide

### Stick to [Simple Haskell](https://www.simplehaskell.org/)
This test suite should remain accessible to contributors who are new to Haskell and/or the GraphQL engine codebase. Consider the [power-to-weight](https://www.snoyman.com/blog/2019/11/boring-haskell-manifesto/#power-to-weight-ratio) ratio of features, language extensions or abstractions before you introduce them. For example, try to fully leverage Haskell '98 or 2010 features before making use of more advanced ones.

### Write small, atomic, autonomous specs
Small: Keep specs short and succinct wherever possible. Consider reorganising modules that grow much longer than ~200-300 lines of code.

*For example: The [`TestGraphQLQueryBasic*` pytest class](../tests-py/test_graphql_queries.py#L251) was ported to the hspec suite as separate `BasicFields`, `LimitOffset`, `Where`, `Ordering`, `Directives` and `Views` specs.*

Atomic: Each spec should test only one feature against the backends (or contexts) that support it. Each module should contain only the context setup and teardown, and the tests themselves. The database schema, test data, and feature expectations should be easy to reason about without navigating to different module.

*For example: [`BasicFieldsSpec.hs`](Test/BasicFieldsSpec.hs)*

Autonomous: Each test should run independently of other tests, and not be dependent on the results of a previous test. Shared test state, where unavoidable, should be made explicit.

*For example: [Remote relationship tests](Test/RemoteRelationship/) explicitly require shared state.*

### Use the `Harness.*` hierarchy for common functions
Avoid functions or types in tests, other than calls to the `Harness.*` API.

Any supporting code should be in the `Harness.*` hierarchy and apply broadly to the test suites overall.