# create\_test\_session
dbnl.create_test_session(
*,
experiment_run: Run,
baseline: Optional[Union[Run, RunQuery]] = None,
include_tags: Optional[List[str]] = None,
exclude_tags: Optional[List[str]] = None,
require_tags: Optional[List[str]] = None,
) -> TestSession:
Start evaluating Tests associated with a Run. Typically, the Run you just completed will be the "Experiment" and you'll compare it to some earlier "Baseline Run".
{% hint style="warning" %}
The Run must already have [Results reported](/v0.20.x/using-distributional/python-sdk/sdk-functions/run-results/report_results-2.md) and be closed before a Test Session can begin.
{% endhint %}
{% hint style="info" %}
A Run must be closed for all [uploaded results](/v0.20.x/using-distributional/python-sdk/sdk-functions/run-results/report_results-2.md) to be shown on the UI.
{% endhint %}
## Parameters
| Arguments | Description |
|---|
experiment_run | The dbnl Run to create the TestSession for. |
baseline | The dbnl Run or RunQuery to compare the experiment_runagainst. If None(or omitted), will use the baselinedefined in the TestConfig |
include_tags | An optional list of Test Tags to be included. All Tests with any of the tags in this list will be ran after the run is complete. |
exclude_tags | An optional list of Test Tags to be excluded. All Tests with any of the tags in this list will be skipped after the run is complete. |
require_tags | An optional list of Test Tags that are required. Only tests with all the tags in this list will be ran after the run is complete. |
### Managing Tags
Suppose we have the following Tests with the associated Tags in our Project
* Test1 with tags \["A", "B"]
* Test2 with tags \["A"]
* Test3 with tags \["B"]
`dbnl.create_test_session(..., include_tags=["A", "B"])` will trigger Tests 1, 2, 3 to be executed.
`dbnl.create_test_session(..., require_tags=["A", "B"])` will only trigger Test 1.
`dbnl.create_test_session(..., exclude_tags=["A"])` will trigger Test 3.
`dbnl.create_test_session(..., include_tags=["A"], exclude_tags=["B"])` will trigger Test 2.
## Examples
### Basic example
```python
dbnl.create_test_session(
experiment_run=new_run,
baseline=baseline_run,
)
```
### Using a Run Query as a Baseline
```python
dbnl.create_test_session(
experiment_run=new_run,
baseline=baseline_run_query,
)
```
### When Baseline Run has already been set
```python
dbnl.create_test_session(
experiment_run=new_run,
)
```
[^1]: [TestSession](/v0.20.x/using-distributional/python-sdk/sdk-objects/testsession.md)
---
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