---
title: "Test-CatDataSource"
description: "Test-CatDataSource — test that one data source of the open project, or all of them, answer, without running any test."
url: "https://docs.justcat.it/reference/powershell-module/test-catdatasource/"
---
# Test-CatDataSource

## Synopsis

```powershell
Test-CatDataSource [[-Name] <string>] [-DataSource <DataSourceDefinition[]>]
```

## Parameters

| Parameter | Type | Position | Default | Meaning |
|-----------|------|----------|---------|---------|
| `-Name` | string | 0 | none | Name of a data source of the open project (exact name, as in the project file). Omit it to test every data source of the project. |
| `-DataSource` | DataSourceDefinition[] | | none | Data source definitions to test, from the pipeline or by name. Each one is tested as it is, whether or not it is part of the project. |

With neither `-Name` nor `-DataSource`, every data source of the project is tested, in the order of the project.

## What it does

For each tested data source it does what the data source's provider does when a test uses it, with a harmless statement in place of a real one. What counts as *answering* depends on the provider:

| Provider | What the test proves |
|----------|----------------------|
| SQL Server, PostgreSQL, MySQL, ClickHouse, Snowflake, Teradata, Databricks, Oracle, DuckDB@1 | Connects, runs a one-row statement (`SELECT 'cat' AS cat`, with `FROM DUAL` for Oracle) and reads the row. |
| DAX and Power BI providers (Windows) | Connects and reads the row of `EVALUATE ROW("cat", "cat")`. |
| ODBC, and the OleDb CSV and Excel providers (Windows) | Opens the connection and stops; no statement is run. |
| Excel@1, YAML | The file exists. The file is not read. |
| Csv@1 | The folder exists. |
| Excel@2 | The workbook file exists. It is not loaded — that is what a run does, and it can take seconds on a large file. |
| Csv@2 | At least one file matches the connection string. A pattern that matches nothing is caught only when no other entry of the list matches either. |

The statement has a fixed timeout of 30 seconds; opening the connection is bounded by the driver's own connect timeout from the connection string, and there are no retries. A Databricks SQL warehouse or cluster that was stopped starts on the first query and can take minutes: the result says it may still be starting, so test again a few minutes later.

## Output

One `DataSourceTestResult` per data source, written as each arrives:

| Property | Meaning |
|----------|---------|
| `Name` | The data source name as written in the project; `(unnamed)` when there is none. |
| `Provider` | The provider and version, as written, for example `SqlServer@2`. |
| `Success` | `$true` when the data source answered. |
| `Message` | What was proven (`Connected and read one row`, `File exists: …`), or the error. |
| `Duration` | A `TimeSpan`. |

## Errors

A failed test is a result with `Success` set to `$false`, **not** an error of the cmdlet, so `Test-CatDataSource | Where-Object { -not $_.Success }` lists what is broken. The cmdlet itself fails when nothing is open (`There is no open CAT project. Open a project first.`) and for an unknown name (`The provided data source name '…' was not found. Only data sources with these names are available: …`).

## Examples

```powershell
Open-CatProject -Path 'D:\Testing\Aero.cat.yaml'

# all data sources
Test-CatDataSource

# one
Test-CatDataSource AERO_PROD

# only the broken ones
Test-CatDataSource | Where-Object { -not $_.Success } | Format-Table Name, Message

# some of them: the parentheses make PowerShell hand over the data sources one by one
(Get-CatDataSource) | Where-Object Name -like 'AERO*' | Test-CatDataSource

# all of them through the pipeline
Get-CatDataSource | Test-CatDataSource
```

## Related

- [Introduction](https://docs.justcat.it/reference/powershell-module/introduction/ "Introduction") — session model, logging, errors, sign-in.
- [`Invoke-CatCommand`](https://docs.justcat.it/reference/powershell-module/invoke-catcommand/ "Invoke-CatCommand") — run a statement of your own once the data source answers.
- [`Get-CatDataSource`](https://docs.justcat.it/reference/powershell-module/get-catdatasource/ "Get-CatDataSource") — the names to use.
- [Providers](https://docs.justcat.it/reference/data-sources/providers/ "Providers") — what each provider accepts.