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promql: extend test scripting language to support asserting on expected error message (#14038)

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Add ability to assert that a query fails with a particular error message

This also adds documentation for the test scripting language in general,
including the new feature.

Signed-off-by: Charles Korn <charles.korn@grafana.com>

---------

Signed-off-by: Charles Korn <charles.korn@grafana.com>
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Charles Korn 2024-06-07 01:56:25 +10:00 committed by GitHub
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128
promql/promqltest/README.md Normal file
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@ -0,0 +1,128 @@
# 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`
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](../../docs/configuration/unit_testing_rules.md#series)
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 7
* 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.
## `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.
Both instant and range queries are supported.
The syntax is as follows:
```
# Instant query
eval instant at <time> <query>
<series> <points>
...
<series> <points>
# Range query
eval range from <start> to <end> step <step> <query>
<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`)
* `<series>` and `<points>` specify the expected values, and follow the same syntax as for `load` above
For example:
```
eval instant at 1m sum by (env) (my_metric)
{env="prod"} 5
{env="test"} 20
eval range from 0 to 3m step 1m sum by (env) (my_metric)
{env="prod"} 2 5 10 20
{env="test"} 10 20 30 45
```
Instant queries also support asserting that the series are returned in exactly the order specified: use `eval_ordered instant ...` instead of `eval instant ...`.
This is not supported for range queries.
It is also possible to test that queries fail: use `eval_fail instant ...` or `eval_fail range ...`.
`eval_fail` optionally takes an expected error message string or regexp to assert that the error message is as expected.
For example:
```
# Assert that the query fails for any reason without asserting on the error message.
eval_fail instant at 1m ceil({__name__=~'testmetric1|testmetric2'})
# Assert that the query fails with exactly the provided error message string.
eval_fail instant at 1m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_message vector cannot contain metrics with the same labelset
# Assert that the query fails with an error message matching the regexp provided.
eval_fail instant at 1m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp (vector cannot contain metrics .*|something else went wrong)
```

45
promql/promqltest/test.go
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@ -306,6 +306,21 @@ func (t *test) parseEval(lines []string, i int) (int, *evalCmd, error) {
i--
break
}
if cmd.fail && strings.HasPrefix(defLine, "expected_fail_message") {
cmd.expectedFailMessage = strings.TrimSpace(strings.TrimPrefix(defLine, "expected_fail_message"))
break
}
if cmd.fail && strings.HasPrefix(defLine, "expected_fail_regexp") {
pattern := strings.TrimSpace(strings.TrimPrefix(defLine, "expected_fail_regexp"))
cmd.expectedFailRegexp, err = regexp.Compile(pattern)
if err != nil {
return i, nil, formatErr("invalid regexp '%s' for expected_fail_regexp: %w", pattern, err)
}
break
}
if f, err := parseNumber(defLine); err == nil {
cmd.expect(0, parser.SequenceValue{Value: f})
break
@ -455,8 +470,10 @@ type evalCmd struct {
step time.Duration
line int
isRange bool // if false, instant query
fail, ordered bool
isRange bool // if false, instant query
fail, ordered bool
expectedFailMessage string
expectedFailRegexp *regexp.Regexp
metrics map[uint64]labels.Labels
expected map[uint64]entry
@ -645,6 +662,24 @@ func (ev *evalCmd) compareResult(result parser.Value) error {
return nil
}
func (ev *evalCmd) checkExpectedFailure(actual error) error {
if ev.expectedFailMessage != "" {
if ev.expectedFailMessage != actual.Error() {
return fmt.Errorf("expected error %q evaluating query %q (line %d), but got: %s", ev.expectedFailMessage, ev.expr, ev.line, actual.Error())
}
}
if ev.expectedFailRegexp != nil {
if !ev.expectedFailRegexp.MatchString(actual.Error()) {
return fmt.Errorf("expected error matching pattern %q evaluating query %q (line %d), but got: %s", ev.expectedFailRegexp.String(), ev.expr, ev.line, actual.Error())
}
}
// We're not expecting a particular error, or we got the error we expected.
// This test passes.
return nil
}
func formatSeriesResult(s promql.Series) string {
floatPlural := "s"
histogramPlural := "s"
@ -795,7 +830,7 @@ func (t *test) execRangeEval(cmd *evalCmd, engine promql.QueryEngine) error {
res := q.Exec(t.context)
if res.Err != nil {
if cmd.fail {
return nil
return cmd.checkExpectedFailure(res.Err)
}
return fmt.Errorf("error evaluating query %q (line %d): %w", cmd.expr, cmd.line, res.Err)
@ -827,6 +862,10 @@ func (t *test) execInstantEval(cmd *evalCmd, engine promql.QueryEngine) error {
res := q.Exec(t.context)
if res.Err != nil {
if cmd.fail {
if err := cmd.checkExpectedFailure(res.Err); err != nil {
return err
}
continue
}
return fmt.Errorf("error evaluating query %q (line %d): %w", iq.expr, cmd.line, res.Err)

107
promql/promqltest/test_test.go
View file

@ -263,6 +263,60 @@ eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
input: `eval_fail instant at 0s vector(0)`,
expectedError: `expected error evaluating query "vector(0)" (line 1) but got none`,
},
"instant query expected to fail with specific error message, and query fails with that error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_message vector cannot contain metrics with the same labelset
`,
},
"instant query expected to fail with specific error message, and query fails with a different error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_message something else went wrong
`,
expectedError: `expected error "something else went wrong" evaluating query "ceil({__name__=~'testmetric1|testmetric2'})" (line 6), but got: vector cannot contain metrics with the same labelset`,
},
"instant query expected to fail with error matching pattern, and query fails with that error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp vector .* contain metrics
`,
},
"instant query expected to fail with error matching pattern, and query fails with a different error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp something else went wrong
`,
expectedError: `expected error matching pattern "something else went wrong" evaluating query "ceil({__name__=~'testmetric1|testmetric2'})" (line 6), but got: vector cannot contain metrics with the same labelset`,
},
"instant query expected to fail with error matching pattern, and pattern is not a valid regexp": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail instant at 0m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp [
`,
expectedError: `error in eval ceil({__name__=~'testmetric1|testmetric2'}) (line 7): invalid regexp '[' for expected_fail_regexp: error parsing regexp: missing closing ]: ` + "`[`",
},
"instant query with results expected to match provided order, and result is in expected order": {
input: testData + `
eval_ordered instant at 50m sort(http_requests)
@ -384,6 +438,59 @@ eval_fail range from 0 to 10m step 5m ceil({__name__=~'testmetric1|testmetric2'}
input: `eval_fail range from 0 to 10m step 5m vector(0)`,
expectedError: `expected error evaluating query "vector(0)" (line 1) but got none`,
},
"range query expected to fail with specific error message, and query fails with that error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail range from 0 to 10m step 5m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_message vector cannot contain metrics with the same labelset
`,
},
"range query expected to fail with specific error message, and query fails with a different error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail range from 0 to 10m step 5m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_message something else went wrong
`,
expectedError: `expected error "something else went wrong" evaluating query "ceil({__name__=~'testmetric1|testmetric2'})" (line 6), but got: vector cannot contain metrics with the same labelset`,
},
"range query expected to fail with error matching pattern, and query fails with that error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail range from 0 to 10m step 5m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp vector .* contain metrics
`,
},
"range query expected to fail with error matching pattern, and query fails with a different error": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail range from 0 to 10m step 5m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp something else went wrong
`,
expectedError: `expected error matching pattern "something else went wrong" evaluating query "ceil({__name__=~'testmetric1|testmetric2'})" (line 6), but got: vector cannot contain metrics with the same labelset`,
},
"range query expected to fail with error matching pattern, and pattern is not a valid regexp": {
input: `
load 5m
testmetric1{src="a",dst="b"} 0
testmetric2{src="a",dst="b"} 1
eval_fail range from 0 to 10m step 5m ceil({__name__=~'testmetric1|testmetric2'})
expected_fail_regexp [
`,
expectedError: `error in eval ceil({__name__=~'testmetric1|testmetric2'}) (line 7): invalid regexp '[' for expected_fail_regexp: error parsing regexp: missing closing ]: ` + "`[`",
},
"range query with from and to timestamps in wrong order": {
input: `eval range from 10m to 9m step 5m vector(0)`,
expectedError: `error in eval vector(0) (line 1): invalid test definition, end timestamp (9m) is before start timestamp (10m)`,