loki/pkg/compute/testdata

Compute tests

This directory contains test files written in a Domain Specific Language (DSL) for testing compute package operations. The DSL provides a concise way to specify test cases for columnar data operations.

Tests are run by the TestCompute function in compute_test.go.

DSL grammar

Cases        := Case*
Case         := Function Datum* Selection? "->" Datum TERMINATOR
Datum        := TypedValue
Selection    := "select" ":" "[" Scalar* "]" 
TypedValue   := Type ":" Value

Type         := "bool" | "int64" | "uint64" | "utf8" | "null"

Value        := Scalar | Array
Scalar       := <literal> | "null"
Array        := "[" Scalar* "]"

TERMINATOR   := "\n"

Comments start with # and continue to the end of the line. All whitespace is ignored.

Data types

• bool: Boolean values (true, false, null)
• int64: Signed 64-bit integers (e.g., -42, 123)
• uint64: Unsigned 64-bit integers (e.g., 0, 456)
• utf8: UTF-8 strings, must be quoted (e.g., "hello", "test string"). Escape sequences are supported.
• null: Explicit null type for null-only values

Adding new compute functions

When a new compute function is added, update compute_test.go to invoke the proper function based on a given name.

Depending on the signature of the compute function being called, some functions may need special argument handling, such as converting a columnar.Datum into a compiled regular expression.

Error testing

The DSL cannot be used to define test cases where the compute function is expected to fail. These cases should instead be tested in Go test files.

Advanced tests

Advanced compute functions, such as compute functions operating on record batches or structs, are better left to the Go test files. They are more complex and require more setup than the DSL can handle.