156 lines
4.1 KiB
Markdown
156 lines
4.1 KiB
Markdown
---
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title: testing.diff() function
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description: >
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`testing.diff()` produces a diff between two streams.
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menu:
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flux_v0_ref:
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name: testing.diff
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parent: testing
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identifier: testing/diff
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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#L144-L155
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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.diff()` produces a diff between two streams.
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The function matches tables from each stream based on group keys.
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For each matched table, it produces a diff.
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Any added or removed rows are added to the table as a row.
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An additional string column with the name diff is created and contains a
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`-` if the row was present in the `got` table and not in the `want` table or
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`+` if the opposite is true.
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`diff()` function emits at least one row if the tables are
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different and no rows if the tables are the same.
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The exact diff produced may change.
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`diff()` can be used to perform in-line diffs in a query.
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##### Function type signature
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```js
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(
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<-got: stream[A],
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want: stream[A],
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?epsilon: B,
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?nansEqual: C,
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?verbose: D,
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) => stream[{A with _diff: string}]
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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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### got
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Stream containing data to test. Default is piped-forward data (`<-`).
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### want
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({{< req >}})
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Stream that contains data to test against.
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### epsilon
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Specify how far apart two float values can be, but still considered equal. Defaults to 0.000000001.
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### verbose
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Include detailed differences in output. Default is `false`.
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### nansEqual
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Consider `NaN` float values equal. Default is `false`.
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## Examples
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- [Output a diff between two streams of tables](#output-a-diff-between-two-streams-of-tables)
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- [Return a diff between a stream of tables an the expected output](#return-a-diff-between-a-stream-of-tables-an-the-expected-output)
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### Output a diff between two streams of tables
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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 =
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sampledata.int()
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|> map(fn: (r) => ({r with _value: if r._value > 15 then r._value + 1 else r._value}))
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testing.diff(got: got, want: want)
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```
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{{< expand-wrapper >}}
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{{% expand "View example input" %}}
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#### Input data
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| _diff | *tag | _time | _value |
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| ------ | ---- | -------------------- | ------- |
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| | t1 | 2021-01-01T00:00:00Z | -2 |
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| | t1 | 2021-01-01T00:00:10Z | 10 |
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| | t1 | 2021-01-01T00:00:20Z | 7 |
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| - | t1 | 2021-01-01T00:00:30Z | 17 |
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| + | t1 | 2021-01-01T00:00:30Z | 18 |
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| | t1 | 2021-01-01T00:00:40Z | 15 |
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| | t1 | 2021-01-01T00:00:50Z | 4 |
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| _diff | *tag | _time | _value |
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| ------ | ---- | -------------------- | ------- |
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| - | t2 | 2021-01-01T00:00:00Z | 19 |
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| + | t2 | 2021-01-01T00:00:00Z | 20 |
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| | t2 | 2021-01-01T00:00:10Z | 4 |
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| | t2 | 2021-01-01T00:00:20Z | -3 |
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| - | t2 | 2021-01-01T00:00:30Z | 19 |
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| + | t2 | 2021-01-01T00:00:30Z | 20 |
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| | t2 | 2021-01-01T00:00:40Z | 13 |
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| | t2 | 2021-01-01T00:00:50Z | 1 |
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{{% /expand %}}
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{{< /expand-wrapper >}}
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### Return a diff between a stream of tables an the expected output
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```js
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import "testing"
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want = from(bucket: "backup-example-bucket") |> range(start: -5m)
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from(bucket: "example-bucket")
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|> range(start: -5m)
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|> testing.diff(want: want)
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```
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