adding unit tests for common pkg

Signed-off-by: Jaydip Gabani <[email protected]>

pkg/metrics/exporters/common/common_test.go

@@ -0,0 +1,62 @@
+package common
+
+import (
+	"testing"
+
+	testmetric "github.com/open-policy-agent/gatekeeper/v3/test/metrics"
+	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/otel/sdk/metric"
+)
+
+func TestAddReader(t *testing.T) {
+	// Mock the required variables
+	rdr := metric.NewPeriodicReader(new(testmetric.FnExporter))
+
+	tests := []struct {
+		name            string
+		options         []metric.Option
+		requiredReaders int
+		wantedReaders   int
+	}{
+		{
+			name:            "Only one metrics-backend is available",
+			options:         []metric.Option{metric.WithReader(rdr)},
+			requiredReaders: 1,
+			wantedReaders:   1,
+		},
+		{
+			name:            "More than one metrics-backend is available",
+			options:         []metric.Option{metric.WithReader(rdr), metric.WithReader(rdr)},
+			requiredReaders: 2,
+			wantedReaders:   2,
+		},
+		{
+			name:            "Two metrics-backends are available, but one is in error state",
+			options:         []metric.Option{metric.WithReader(rdr), nil},
+			requiredReaders: 2,
+			wantedReaders:   1,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			SetRequiredReaders(tt.requiredReaders)
+			opts = []metric.Option{}
+
+			for _, opt := range tt.options {
+				AddReader(opt)
+			}
+
+			assert.Equal(t, tt.wantedReaders, len(opts))
+		})
+	}
+}
+
+func TestSetRequiredReaders(t *testing.T) {
+	// Call the function under test
+	SetRequiredReaders(5)
+	assert.Equal(t, 5, requiredReaders)
+
+	SetRequiredReaders(-1)
+	assert.Equal(t, -1, requiredReaders)
+}