The PromQL test scripting language

This package contains two things:

• an implementation of a test scripting language for PromQL engines
• a predefined set of tests written in that scripting language

The predefined set of tests can be run against any PromQL engine implementation by calling promqltest.RunBuiltinTests(). Any other test script can be run with promqltest.RunTest().

The rest of this document explains the test scripting language.

Each test script is written in plain text.

Comments can be given by prefixing the comment with a #, for example:

# This is a comment.

Each test file contains a series of commands. There are three kinds of commands:

• load
• clear
• eval

Note: The eval command variants (eval_fail, eval_warn, eval_info, and eval_ordered) are deprecated. Use the new expect lines instead (explained in the eval command section). Additionally, expected_fail_message and expected_fail_regexp are also deprecated.

Each command is executed in the order given in the file.

load command

load adds some data to the test environment.

The syntax is as follows:

load <interval>
    <series> <points>
    ...
    <series> <points>

• <interval> is the step between points (eg. 1m or 30s)
• <series> is a Prometheus series name in the usual metric{label="value"} syntax
• <points> is a specification of the points to add for that series, following the same expanding syntax as for promtool unittest documented here

For example:

load 1m
    my_metric{env="prod"} 5 2+3x2 _ stale {{schema:1 sum:3 count:22 buckets:[5 10 7]}}

… will create a single series with labels my_metric{env="prod"}, with the following points:

• t=0: value is 5
• t=1m: value is 2
• t=2m: value is 5
• t=3m: value is 8
• t=4m: no point
• t=5m: stale marker
• t=6m: native histogram with schema 1, sum -3, count 22 and bucket counts 5, 10 and 7

Each load command is additive - it does not replace any data loaded in a previous load command. Use clear to remove all loaded data.

Native histograms with custom buckets (NHCB)

When loading a batch of classic histogram float series, you can optionally append the suffix _with_nhcb to convert them to native histograms with custom buckets and load both the original float series and the new histogram series.

clear command

clear removes all data previously loaded with load commands.

eval command

eval runs a query against the test environment and asserts that the result is as expected. It requires the query to succeed without any failures unless an expect fail line is provided. Previously eval expected no info or warn annotation, but now expect no_info and expect no_warn lines must be explicitly provided.

Both instant and range queries are supported.

The syntax is as follows:

# Instant query
eval instant at <time> <query>
    <expect>
    ...
    <expect>
    <series> <points>
    ...
    <series> <points>
    
# Range query
eval range from <start> to <end> step <step> <query>
    <expect>
    ...
    <expect>
    <series> <points>
    ...
    <series> <points>

• <time> is the timestamp to evaluate the instant query at (eg. 1m)
• <start> and <end> specify the time range of the range query, and use the same syntax as <time>
• <step> is the step of the range query, and uses the same syntax as <time> (eg. 30s)
• <expect>(optional) specifies expected annotations, errors, or result ordering.
• <expect range vector> (optional) for an instant query you can specify expected range vector timestamps
• <expect string> "<string>" (optional) for matching a string literal
• <series> and <points> specify the expected values, and follow the same syntax as for load above

Special handling of counter reset hints in native histograms

Native histograms as part of <points> may or may not contain an explicit counter_reset_hint property. If a counter_reset_hint is provided explicitly, the counter reset hint of the histogram is tested to have the provided value (unknown, reset, not_reset, or gauge). However, if no counter_reset_hint is specified, the counter_reset_hint is not tested at all (rather than testing for the usual default value unknown).

expect string

This can be used to specify that a string literal is the expected result.

Note that this is only supported on instant queries.

For example;

eval instant at 50m ("Foo")
 expect string "Foo"

The expected string value must be within quotes. Double or back quotes are supported.

expect range vector

This can be used to specify the expected timestamps on a range vector resulting from an instant query.

expect range vector <start> to <end> step <step>

For example;

load 10s
  some_metric{env="a"} 1+1x5
  some_metric{env="b"} 2+2x5
eval instant at 1m some_metric[1m]
  expect range vector from 10s to 1m step 10s
  some_metric{env="a"} 2 3 4 5 6
  some_metric{env="b"} 4 6 8 10 12

expect Syntax

expect <type> <match_type>: <string>

Parameters

• <type> is the expectation type:
  • fail expects the query to fail.
  • info expects the query to return at least one info annotation.
  • warn expects the query to return at least one warn annotation.
  • no_info expects the query to return no info annotation.
  • no_warn expects the query to return no warn annotation.
  • ordered expects the query to return the results in the specified order.
• <match_type> (optional) specifies message matching type for annotations:
  • msg for exact string match.
  • regex for regular expression match.
  • Not applicable for ordered, no_info, and no_warn.
• <string> is the expected annotation message.

For example:

eval instant at 1m sum by (env) (my_metric)
    expect warn
    expect no_info
    {env="prod"} 5
    {env="test"} 20
    
eval range from 0 to 3m step 1m sum by (env) (my_metric)
    expect warn msg: something went wrong
    expect info regex: something went (wrong|boom)
    {env="prod"} 2 5 10 20
    {env="test"} 10 20 30 45

eval instant at 1m ceil({__name__=~'testmetric1|testmetric2'})
expect fail

eval instant at 1m ceil({__name__=~'testmetric1|testmetric2'})
expect fail msg: "vector cannot contain metrics with the same labelset"

eval instant at 1m ceil({__name__=~'testmetric1|testmetric2'})
expect fail regex: "vector cannot contain metrics .*|something else went wrong"

eval instant at 1m sum by (env) (my_metric)
expect ordered
{env="prod"} 5
{env="test"} 20

There can be multiple <expect> lines for a given <type>. Each <type> validates its corresponding annotation, error, or ordering while ignoring others.

Every <expect> line must match at least one corresponding annotation or error.

If at least one <expect> line of type warn or info is present, then all corresponding annotations must have a matching expect line.

Migrating Test Files to the New Syntax

• All .test files in the directory specified by the --dir flag will be updated in place.
• Deprecated syntax will be replaced with the recommended expect line statements.

Usage:

go run ./promql/promqltest/cmd/migrate/main.go --mode=strict [--dir=<directory>]

The --mode flag controls how expectations are migrated:

• strict: Strictly migrates all expectations to the new syntax. This is probably more verbose than intended because the old syntax implied many constraints that are often not needed.
• basic: Like strict but never creates no_info and no_warn expectations. This can be a good starting point to manually add no_info and no_warn expectations and/or remove info and warn expectations as needed.
• tolerant: Only creates expect fail and expect ordered where appropriate. All desired expectations about presence or absence of info and warn have to be added manually.

All three modes create valid passing tests from previously passing tests. basic and tolerant just test fewer expectations than the previous tests.

The --dir flag specifies the directory containing test files to migrate.