# Testing an Analyzer

An analyzer declares what it takes and gives in its schemas (see
[The contract](../analysis/writing.md#the-contract)), so much of it can be checked
without real data: that the schemas are valid, that `analyze()` accepts exactly the
declared inputs, and that its outputs match what it declares. `AnalyzerPipeline`, in
`plesty.lib.test.analyzer_pipeline`, runs these checks on inputs it generates from the
schema.

| Test | Checks |
|---|---|
| `test_analyzer_subclass` | the module has a public `Analyzer` subclass that can be created with the given settings |
| `test_schema_integrity` | both schemas are non-empty, their types are known, their shapes are well-formed |
| `test_analyze_signature` | `analyze()` takes exactly the inputs `input_schema` declares |
| `test_mock_roundtrip` | generated inputs produce outputs that match `output_schema` |
| `test_provenance_stamped` | the outputs carry their provenance |

An analyzer module exposes one pytest test per check:

```python
# tests/test_pipeline.py
import numpy as np
from plesty.lib.test.analyzer_pipeline import AnalyzerPipeline

from plesty.power_peak import PowerPeak

PIPELINE = AnalyzerPipeline(PowerPeak, mock_inputs={"power": np.array([0.002, 0.008, 0.004])})


def test_analyzer_subclass():
    PIPELINE.test_analyzer_subclass()


def test_schema_integrity():
    PIPELINE.test_schema_integrity()


def test_analyze_signature():
    PIPELINE.test_analyze_signature()


def test_mock_roundtrip():
    PIPELINE.test_mock_roundtrip()


def test_provenance_stamped():
    PIPELINE.test_provenance_stamped()
```

Inputs the analyzer needs to be realistic, such as an image with actual features or a
power curve with a peak, are given in `mock_inputs`. Every other input is generated:
zeros of the declared shape, or a neutral number. Arguments after the class, other
than `mock_inputs`, are passed to its constructor. `PIPELINE.run_mock_pipeline()` runs
all five checks at once.

plesty-sdk, PLESTY's developer tool, looks for these five tests and runs them as gate
`a1` of `plesty check` before the module may be published (see
[Which tests each module runs](index.md#which-tests-each-module-runs)).