测试
当依赖 OpenTelemetry 来满足您的可观察性需求时，验证某些 Span 是否已创建以及属性是否已正确设置非常重要。例如，您能确定您是否将正确的元数据附加到了最终为 SLO 提供动力的数据中吗？本文档介绍了一种处理此类验证的方法。
设置
在 Elixir/Erlang 中进行测试仅需要 opentelemetry 和 opentelemetry_api 库
{deps, [{opentelemetry_api, "~> 1.4"},
{opentelemetry, "~> 1.5"}]}.
def deps do
[
{:opentelemetry_api, "~> 1.4"},
{:opentelemetry, "~> 1.5"}
]
end
将您的 exporter 设置为 :none，将 Span Processor 设置为 :otel_simple_processor。这可以确保您的测试不会实际将数据导出到目的地，并且 Span 在处理后可以进行分析。
%% config/sys.config.src
{opentelemetry,
[{traces_exporter, none},
{processors,
[{otel_simple_processor, #{}}]}]}
# config/test.exs
import Config
config :opentelemetry,
traces_exporter: :none
config :opentelemetry, :processors, [
{:otel_simple_processor, %{}}
]
来自 入门指南 的 hello 函数的修改版本将作为我们的测试用例
%% apps/otel_getting_started/src/otel_getting_started.erl
-module(otel_getting_started).
-export([hello/0]).
-include_lib("opentelemetry_api/include/otel_tracer.hrl").
hello() ->
%% start an active span and run a local function
?with_span(<<"operation">>, #{}, fun nice_operation/1).
nice_operation(_SpanCtx) ->
?set_attributes([{a_key, <<"a value">>}]),
world
# lib/otel_getting_started.ex
defmodule OtelGettingStarted do
require OpenTelemetry.Tracer, as: Tracer
def hello do
Tracer.with_span "operation" do
Tracer.set_attributes([{:a_key, "a value"}])
:world
end
end
end
测试
-module(otel_getting_started_SUITE).
-compile(export_all).
-include_lib("stdlib/include/assert.hrl").
-include_lib("common_test/include/ct.hrl").
-include_lib("opentelemetry/include/otel_span.hrl").
-define(assertReceive(SpanName),
receive
{span, Span=#span{name=SpanName}} ->
Span
after
1000 ->
ct:fail("Did not receive the span after 1s")
end).
all() ->
[greets_the_world].
init_per_suite(Config) ->
application:load(opentelemetry),
application:set_env(opentelemetry, processors, [{otel_simple_processor, #{}}]),
{ok, _} = application:ensure_all_started(opentelemetry),
Config.
end_per_suite(_Config) ->
_ = application:stop(opentelemetry),
_ = application:unload(opentelemetry),
ok.
init_per_testcase(greets_the_world, Config) ->
otel_simple_processor:set_exporter(otel_exporter_pid, self()),
Config.
end_per_testcase(greets_the_world, _Config) ->
otel_simple_processor:set_exporter(none),
ok.
greets_the_world(_Config) ->
otel_getting_started:hello(),
ExpectedAttributes = otel_attributes:new(#{a_key => <<"a_value">>}, 128, infinity),
#span{attributes=ReceivedAttributes} = ?assertReceive(<<"operation">>),
%% use an assertMatch instead of matching in the `receive'
%% so we get a nice error message if it fails
?assertMatch(ReceivedAttributes, ExpectedAttributes),
ok.
defmodule OtelGettingStartedTest do
use ExUnit.Case
# Use Record module to extract fields of the Span record from the opentelemetry dependency.
require Record
@fields Record.extract(:span, from: "deps/opentelemetry/include/otel_span.hrl")
# Define macros for `Span`.
Record.defrecordp(:span, @fields)
test "greets the world" do
# Set exporter to :otel_exporter_pid, which sends spans
# to the given process - in this case self() - in the format {:span, span}
:otel_simple_processor.set_exporter(:otel_exporter_pid, self())
# Call the function to be tested.
OtelGettingStarted.hello()
# Use Erlang's `:otel_attributes` module to create attributes to match against.
# See the `:otel_events` module for testing events.
attributes = :otel_attributes.new([a_key: "a value"], 128, :infinity)
# Assert that the span emitted by OtelGettingStarted.hello/0 was received and contains the desired attributes.
assert_receive {:span,
span(
name: "operation",
attributes: ^attributes
)}
end
end