Use a TB interface in metricdatatest (#4483)

* use testing.TB interface in metricdatatest

* add changelog entry

* use our own TB interface

* Update CHANGELOG.md

Co-authored-by: Robert Pająk <[email protected]>

* rename TB to TestingT

* SIG meeting feedback

* ensure *testing.T implements TestingT

* Update sdk/metric/metricdata/metricdatatest/assertion.go

Co-authored-by: Robert Pająk <[email protected]>

* change formatting for last testing.TB too

---------

Co-authored-by: Robert Pająk <[email protected]>

CHANGELOG.md

@@ -13,6 +13,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add `WithProducer` option in `go.opentelemetry.op/otel/exporters/prometheus` to restore the ability to register producers on the prometheus exporter's manual reader. (#4473)
 - Add `IgnoreValue` option in `go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest` to allow ignoring values when comparing metrics. (#4447)
 
+### Changed
+
+- Use a `TestingT` interface instead of `*testing.T` struct in `go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest`. (#4483)
+
 ### Deprecated
 
 - The `NewMetricExporter` in `go.opentelemetry.io/otel/bridge/opencensus` was deprecated in `v0.35.0` (#3541).

sdk/metric/metricdata/metricdatatest/assertion.go

@@ -18,7 +18,6 @@ package metricdatatest // import "go.opentelemetry.io/otel/sdk/metric/metricdata
 
 import (
 	"fmt"
-	"testing"
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
@@ -53,6 +52,20 @@ type Datatypes interface {
 	// Aggregation and Value type from metricdata are not included here.
 }
 
+// TestingT is an interface that implements [testing.T], but without the
+// private method of [testing.TB], so other testing packages can rely on it as
+// well.
+// The methods in this interface must match the [testing.TB] interface.
+type TestingT interface {
+	Helper()
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	Error(...any)
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}
+
 type config struct {
 	ignoreTimestamp bool
 	ignoreExemplars bool
@@ -110,7 +123,7 @@ func IgnoreValue() Option {
 
 // AssertEqual asserts that the two concrete data-types from the metricdata
 // package are equal.
-func AssertEqual[T Datatypes](t *testing.T, expected, actual T, opts ...Option) bool {
+func AssertEqual[T Datatypes](t TestingT, expected, actual T, opts ...Option) bool {
 	t.Helper()
 
 	cfg := newConfig(opts)
@@ -178,7 +191,7 @@ func AssertEqual[T Datatypes](t *testing.T, expected, actual T, opts ...Option)
 }
 
 // AssertAggregationsEqual asserts that two Aggregations are equal.
-func AssertAggregationsEqual(t *testing.T, expected, actual metricdata.Aggregation, opts ...Option) bool {
+func AssertAggregationsEqual(t TestingT, expected, actual metricdata.Aggregation, opts ...Option) bool {
 	t.Helper()
 
 	cfg := newConfig(opts)
@@ -190,7 +203,7 @@ func AssertAggregationsEqual(t *testing.T, expected, actual metricdata.Aggregati
 }
 
 // AssertHasAttributes asserts that all Datapoints or HistogramDataPoints have all passed attrs.
-func AssertHasAttributes[T Datatypes](t *testing.T, actual T, attrs ...attribute.KeyValue) bool {
+func AssertHasAttributes[T Datatypes](t TestingT, actual T, attrs ...attribute.KeyValue) bool {
 	t.Helper()
 
 	var reasons []string

sdk/metric/metricdata/metricdatatest/assertion_test.go

@@ -619,6 +619,10 @@ func testDatatypeIgnoreValue[T Datatypes](a, b T, f equalFunc[T]) func(*testing.
 	}
 }
 
+func TestTestingTImplementation(t *testing.T) {
+	assert.Implements(t, (*TestingT)(nil), t)
+}
+
 func TestAssertEqual(t *testing.T) {
 	t.Run("ResourceMetrics", testDatatype(resourceMetricsA, resourceMetricsB, equalResourceMetrics))
 	t.Run("ScopeMetrics", testDatatype(scopeMetricsA, scopeMetricsB, equalScopeMetrics))