diff --git a/pkg/logging/grpc_test.go b/pkg/logging/grpc_test.go
new file mode 100644
index 00000000000..80e8878208a
--- /dev/null
+++ b/pkg/logging/grpc_test.go
@@ -0,0 +1,270 @@
+// Copyright (c) The Thanos Authors.
+// Licensed under the Apache License 2.0.
+
+package logging
+
+import (
+	"testing"
+
+	"github.com/efficientgo/core/testutil"
+)
+
+func TestValidateLevel(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		level   string
+		wantErr bool
+	}{
+		{name: "INFO is valid", level: "INFO", wantErr: false},
+		{name: "DEBUG is valid", level: "DEBUG", wantErr: false},
+		{name: "ERROR is valid", level: "ERROR", wantErr: false},
+		{name: "WARNING is valid", level: "WARNING", wantErr: false},
+		{name: "WARN is invalid", level: "WARN", wantErr: true},
+		{name: "empty is invalid", level: "", wantErr: true},
+		{name: "lowercase info is invalid", level: "info", wantErr: true},
+		{name: "unknown level is invalid", level: "TRACE", wantErr: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			err := validateLevel(tc.level)
+			if tc.wantErr {
+				testutil.NotOk(t, err)
+			} else {
+				testutil.Ok(t, err)
+			}
+		})
+	}
+}
+
+func TestGetGRPCLoggingOption(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		logStart bool
+		logEnd   bool
+		wantErr  bool
+	}{
+		{name: "both false returns empty events", logStart: false, logEnd: false, wantErr: false},
+		{name: "only logEnd returns FinishCall", logStart: false, logEnd: true, wantErr: false},
+		{name: "both true returns StartCall and FinishCall", logStart: true, logEnd: true, wantErr: false},
+		{name: "only logStart returns error", logStart: true, logEnd: false, wantErr: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			_, err := getGRPCLoggingOption(tc.logStart, tc.logEnd)
+			if tc.wantErr {
+				testutil.NotOk(t, err)
+			} else {
+				testutil.Ok(t, err)
+			}
+		})
+	}
+}
+
+func TestGetHTTPLoggingOption(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		logStart bool
+		logEnd   bool
+		wantErr  bool
+		wantDec  Decision
+	}{
+		{name: "both false returns NoLogCall", logStart: false, logEnd: false, wantErr: false, wantDec: NoLogCall},
+		{name: "only logEnd returns LogFinishCall", logStart: false, logEnd: true, wantErr: false, wantDec: LogFinishCall},
+		{name: "both true returns LogStartAndFinishCall", logStart: true, logEnd: true, wantErr: false, wantDec: LogStartAndFinishCall},
+		{name: "only logStart returns error", logStart: true, logEnd: false, wantErr: true},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			dec, err := getHTTPLoggingOption(tc.logStart, tc.logEnd)
+			if tc.wantErr {
+				testutil.NotOk(t, err)
+			} else {
+				testutil.Ok(t, err)
+				testutil.Equals(t, tc.wantDec, dec)
+			}
+		})
+	}
+}
+
+func TestCheckOptionsConfigEmpty(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name      string
+		cfg       OptionsConfig
+		wantEmpty bool
+		wantErr   bool
+	}{
+		{
+			name:      "all zero values is empty",
+			cfg:       OptionsConfig{},
+			wantEmpty: true,
+			wantErr:   false,
+		},
+		{
+			name: "level set with decisions is not empty",
+			cfg: OptionsConfig{
+				Level:    "INFO",
+				Decision: DecisionConfig{LogStart: true, LogEnd: true},
+			},
+			wantEmpty: false,
+			wantErr:   false,
+		},
+		{
+			name: "logStart true but no level returns error",
+			cfg: OptionsConfig{
+				Decision: DecisionConfig{LogStart: true},
+			},
+			wantEmpty: false,
+			wantErr:   true,
+		},
+		{
+			name: "logEnd true but no level returns error",
+			cfg: OptionsConfig{
+				Decision: DecisionConfig{LogEnd: true},
+			},
+			wantEmpty: false,
+			wantErr:   true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			isEmpty, err := checkOptionsConfigEmpty(tc.cfg)
+			if tc.wantErr {
+				testutil.NotOk(t, err)
+			} else {
+				testutil.Ok(t, err)
+				testutil.Equals(t, tc.wantEmpty, isEmpty)
+			}
+		})
+	}
+}
+
+func TestFillGlobalOptionConfig(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name      string
+		config    *RequestConfig
+		isGRPC    bool
+		wantLevel string
+		wantStart bool
+		wantEnd   bool
+		wantErr   bool
+	}{
+		{
+			name:      "empty config returns defaults",
+			config:    &RequestConfig{},
+			isGRPC:    true,
+			wantLevel: "ERROR",
+			wantStart: false,
+			wantEnd:   false,
+			wantErr:   false,
+		},
+		{
+			name: "global options are used",
+			config: &RequestConfig{
+				Options: OptionsConfig{
+					Level:    "INFO",
+					Decision: DecisionConfig{LogStart: true, LogEnd: true},
+				},
+			},
+			isGRPC:    true,
+			wantLevel: "INFO",
+			wantStart: true,
+			wantEnd:   true,
+			wantErr:   false,
+		},
+		{
+			name: "grpc options override global",
+			config: &RequestConfig{
+				Options: OptionsConfig{
+					Level:    "INFO",
+					Decision: DecisionConfig{LogStart: true, LogEnd: true},
+				},
+				GRPC: GRPCProtocolConfigs{
+					Options: OptionsConfig{
+						Level:    "DEBUG",
+						Decision: DecisionConfig{LogStart: false, LogEnd: true},
+					},
+				},
+			},
+			isGRPC:    true,
+			wantLevel: "DEBUG",
+			wantStart: false,
+			wantEnd:   true,
+			wantErr:   false,
+		},
+		{
+			name: "http options override global when not grpc",
+			config: &RequestConfig{
+				Options: OptionsConfig{
+					Level:    "INFO",
+					Decision: DecisionConfig{LogStart: true, LogEnd: true},
+				},
+				HTTP: HTTPProtocolConfigs{
+					Options: OptionsConfig{
+						Level:    "WARNING",
+						Decision: DecisionConfig{LogStart: false, LogEnd: true},
+					},
+				},
+			},
+			isGRPC:    false,
+			wantLevel: "WARNING",
+			wantStart: false,
+			wantEnd:   true,
+			wantErr:   false,
+		},
+		{
+			name: "global decision without level returns error",
+			config: &RequestConfig{
+				Options: OptionsConfig{
+					Decision: DecisionConfig{LogStart: true},
+				},
+			},
+			isGRPC:  true,
+			wantErr: true,
+		},
+		{
+			name: "protocol decision without level returns error",
+			config: &RequestConfig{
+				GRPC: GRPCProtocolConfigs{
+					Options: OptionsConfig{
+						Decision: DecisionConfig{LogEnd: true},
+					},
+				},
+			},
+			isGRPC:  true,
+			wantErr: true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			lvl, start, end, err := fillGlobalOptionConfig(tc.config, tc.isGRPC)
+			if tc.wantErr {
+				testutil.NotOk(t, err)
+			} else {
+				testutil.Ok(t, err)
+				testutil.Equals(t, tc.wantLevel, lvl)
+				testutil.Equals(t, tc.wantStart, start)
+				testutil.Equals(t, tc.wantEnd, end)
+			}
+		})
+	}
+}