config: refactor resource code (#4824)

* config: refactor resource code

This moves the resource code out of config.go and into resource.go.

Fixes #4821

Signed-off-by: Alex Boten <aboten@lightstep.com>

* Update resource.go

* Update resource_test.go

---------

Signed-off-by: Alex Boten <aboten@lightstep.com>
Co-authored-by: Robert Pająk <pellared@hotmail.com>

config/config.go

@@ -8,8 +8,6 @@ import (
 	"errors"
 
 	"go.opentelemetry.io/otel/metric"
-	"go.opentelemetry.io/otel/sdk/resource"
-	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -119,13 +117,3 @@ func WithOpenTelemetryConfiguration(cfg OpenTelemetryConfiguration) Configuratio
 
 // TODO: create SDK from the model:
 // - https://github.com/open-telemetry/opentelemetry-go-contrib/issues/4371
-
-func newResource(res *Resource) (*resource.Resource, error) {
-	if res == nil {
-		return resource.Default(), nil
-	}
-	return resource.Merge(resource.Default(),
-		resource.NewWithAttributes(semconv.SchemaURL,
-			semconv.ServiceName(*res.Attributes.ServiceName),
-		))
-}

config/resource.go

@@ -0,0 +1,19 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package config // import "go.opentelemetry.io/contrib/config"
+
+import (
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
+)
+
+func newResource(res *Resource) (*resource.Resource, error) {
+	if res == nil || res.Attributes == nil {
+		return resource.Default(), nil
+	}
+	return resource.Merge(resource.Default(),
+		resource.NewWithAttributes(*res.SchemaUrl,
+			semconv.ServiceName(*res.Attributes.ServiceName),
+		))
+}

config/resource_test.go

@@ -0,0 +1,67 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package config // import "go.opentelemetry.io/contrib/config"
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
+)
+
+func TestNewResource(t *testing.T) {
+	res, err := resource.Merge(resource.Default(),
+		resource.NewWithAttributes(semconv.SchemaURL,
+			semconv.ServiceName("service-a"),
+		))
+	require.NoError(t, err)
+	tests := []struct {
+		name         string
+		config       *Resource
+		wantResource *resource.Resource
+		wantErr      error
+	}{
+		{
+			name:         "no-resource-configuration",
+			wantResource: resource.Default(),
+		},
+		{
+			name:         "resource-no-attributes",
+			config:       &Resource{},
+			wantResource: resource.Default(),
+		},
+		{
+			name: "resource-with-attributes-invalid-schema",
+			config: &Resource{
+				SchemaUrl: ptr("https://opentelemetry.io/invalid-schema"),
+				Attributes: &Attributes{
+					ServiceName: ptr("service-a"),
+				},
+			},
+			wantResource: resource.Empty(),
+			wantErr:      errors.New("cannot merge resource due to conflicting Schema URL"),
+		},
+		{
+			name: "resource-with-attributes-and-schema",
+			config: &Resource{
+				Attributes: &Attributes{
+					ServiceName: ptr("service-a"),
+				},
+				SchemaUrl: ptr(semconv.SchemaURL),
+			},
+			wantResource: res,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := newResource(tt.config)
+			require.Equal(t, tt.wantErr, err)
+			assert.Equal(t, tt.wantResource, got)
+		})
+	}
+}