refactor: add pipeline (#3868)

pkg/parallel/pipeline_test.go

@@ -0,0 +1,82 @@
+package parallel_test
+
+import (
+	"context"
+	"math"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/aquasecurity/trivy/pkg/parallel"
+)
+
+func TestPipeline_Do(t *testing.T) {
+	type field struct {
+		numWorkers int
+		items      []float64
+		onItem     func(float64) (float64, error)
+	}
+	type testCase struct {
+		name    string
+		field   field
+		want    float64
+		wantErr bool
+	}
+	tests := []testCase{
+		{
+			name: "pow",
+			field: field{
+				numWorkers: 5,
+				items: []float64{
+					1,
+					2,
+					3,
+					4,
+					5,
+					6,
+					7,
+					8,
+					9,
+					10,
+				},
+				onItem: func(f float64) (float64, error) {
+					return math.Pow(f, 2), nil
+				},
+			},
+			want: 385,
+		},
+		{
+			name: "ceil",
+			field: field{
+				numWorkers: 3,
+				items: []float64{
+					1.1,
+					2.2,
+					3.3,
+					4.4,
+					5.5,
+					-1.1,
+					-2.2,
+					-3.3,
+				},
+				onItem: func(f float64) (float64, error) {
+					return math.Round(f), nil
+				},
+			},
+			want: 10,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var got float64
+			p := parallel.NewPipeline(tt.field.numWorkers, false, tt.field.items, tt.field.onItem, func(f float64) error {
+				got += f
+				return nil
+			})
+			err := p.Do(context.Background())
+			require.NoError(t, err)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}