74 lines
1.8 KiB
Markdown
74 lines
1.8 KiB
Markdown
---
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title: testing.assertEmpty() function
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description: >
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`testing.assertEmpty()` tests if an input stream is empty. If not empty, the function returns an error.
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menu:
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flux_v0_ref:
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name: testing.assertEmpty
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parent: testing
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identifier: testing/assertEmpty
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weight: 101
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flux/v0/tags: [tests]
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introduced: 0.18.0
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---
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<!------------------------------------------------------------------------------
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IMPORTANT: This page was generated from comments in the Flux source code. Any
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edits made directly to this page will be overwritten the next time the
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documentation is generated.
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To make updates to this documentation, update the function comments above the
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function definition in the Flux source code:
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https://github.com/influxdata/flux/blob/master/stdlib/testing/testing.flux#L92-L92
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Contributing to Flux: https://github.com/influxdata/flux#contributing
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Fluxdoc syntax: https://github.com/influxdata/flux/blob/master/docs/fluxdoc.md
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------------------------------------------------------------------------------->
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`testing.assertEmpty()` tests if an input stream is empty. If not empty, the function returns an error.
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assertEmpty can be used to perform in-line tests in a query.
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##### Function type signature
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```js
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(<-tables: stream[A]) => stream[A]
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```
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{{% caption %}}
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For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
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{{% /caption %}}
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## Parameters
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### tables
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Input data. Default is piped-forward data (`<-`).
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## Examples
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### Check if there is a difference between streams
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This example uses `testing.diff()` to output the difference between two streams of tables.
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`testing.assertEmpty()` checks to see if the difference is empty.
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```js
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import "sampledata"
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import "testing"
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want = sampledata.int()
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got = sampledata.float() |> toInt()
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got
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|> testing.diff(want: want)
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|> testing.assertEmpty()
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```
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