add rbuffer data structure

1 files changed, 106 insertions, 0 deletions

diff --git a/internal/datas/rbuffer_test.go b/internal/datas/rbuffer_test.go
new file mode 100644
index 0000000..456511a
--- /dev/null
+++ b/internal/datas/rbuffer_test.go
@@ -0,0 +1,106 @@
+package datas
+
+import (
+	"fmt"
+	"math/rand"
+	"testing"
+	"time"
+)
+
+func TestRBufferOneElement(t *testing.T) {
+	r, err := NewRBuffer(1)
+	if err != nil {
+		t.Errorf("Expected error creating ring buffer with capacity 1")
+	}
+
+	testRBufferValues(t, r, []string{"Hello world"})
+	testRBufferValues(t, r, []string{"Hello world", "Hello universe"})
+}
+
+func TestRBuffer(t *testing.T) {
+	if _, err := NewRBuffer(0); err == nil {
+		t.Errorf("Expected error creating ring buffer with capacity 0")
+	}
+
+	r, err := NewRBuffer(10)
+	if err != nil {
+		t.Errorf("Error creating ring buffer with capacity 10: %v", err)
+	}
+
+	fiveValues := []string{
+		"42 is the answer!",
+		"Scroption: Get over here!",
+		"Have you swiped your nectar card?",
+		"Please mind the gap between the train and the platform!",
+		"Visit DTail at https://dtail.dev",
+	}
+	testRBufferValues(t, r, fiveValues)
+
+	moreFiveValues := []string{
+		"I love Golang",
+		"As a contrast, I also love Perl",
+		"Mimecast: Stop Bad Things From Happening to Good Organizations",
+		"We are the Buetow Brothers",
+		"London is calling",
+	}
+	tenValues := append(fiveValues, moreFiveValues...)
+	testRBufferValues(t, r, tenValues)
+}
+
+func TestRandomRBuffer(t *testing.T) {
+	for i := 0; i < 100; i++ {
+		testRandomRBuffer(t)
+	}
+}
+
+func testRandomRBuffer(t *testing.T) {
+	rand.Seed(time.Now().UnixNano())
+
+	maxCapacity := 1000
+	minCapacity := 1
+	capacity := rand.Intn(maxCapacity-minCapacity) + minCapacity
+	r, err := NewRBuffer(capacity)
+	if err != nil {
+		t.Errorf("Error creating ring buffer with capacity %d: %v", capacity, err)
+	}
+
+	numValues := rand.Intn(capacity * 2)
+	values := make([]string, numValues)
+	for i := 0; i < numValues; i++ {
+		values = append(values, fmt.Sprintf("%d.%d", i, rand.Int()))
+	}
+
+	testRBufferValues(t, r, values)
+}
+
+func testRBufferValues(t *testing.T, r *RBuffer, values []string) {
+	value, ok := r.Get()
+	if ok {
+		t.Errorf("Expected not ok reading from empty ring buffer but got ok and  value '%s'", value)
+	}
+
+	for _, value := range values {
+		r.Add(value)
+	}
+
+	expectedValues := values
+	overCapacity := len(values) - r.Capacity
+	if overCapacity > 0 {
+		expectedValues = values[overCapacity:]
+	}
+
+	for _, expected := range expectedValues {
+		value, ok := r.Get()
+		if !ok {
+			t.Errorf("Expected value '%s' but got nothing", expected)
+		}
+		if value != expected {
+			t.Errorf("Expected value '%s' but got value '%v'", expected, value)
+		}
+	}
+
+	value, ok = r.Get()
+	if ok {
+		t.Errorf("Expected not ok reading from empty ring buffer but got ok and  value '%s'", value)
+	}
+}