test: add more test cases

append_test.go

@@ -1,6 +1,7 @@
 package cheapcash_test
 
 import (
+	"errors"
 	"math/rand"
 	"strconv"
 	"testing"
@@ -31,3 +32,17 @@ func TestAppend(t *testing.T) {
 		t.Errorf("expected %s, got %v", "HelloWorld", string(r))
 	}
 }
+
+func TestAppend_NotExists(t *testing.T) {
+	rand := strconv.Itoa(rand.Int())
+	c := cheapcash.Default()
+
+	err := c.Append(rand, []byte("Hello"))
+	if err == nil {
+		t.Error("expected an error, got nil")
+	}
+
+	if !errors.Is(err, cheapcash.ErrNotExists) {
+		t.Errorf("expected %v, got %v", cheapcash.ErrNotExists, err)
+	}
+}

reader_test.go

@@ -1,6 +1,7 @@
 package cheapcash_test
 
 import (
+	"errors"
 	"math/rand"
 	"strconv"
 	"sync"
@@ -57,3 +58,17 @@ func TestRead_Concurrency(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestRead_NotExists(t *testing.T) {
+	rand := strconv.Itoa(rand.Int())
+	c := cheapcash.Default()
+
+	_, err := c.Read(rand)
+	if err == nil {
+		t.Error("expected an error, got nil")
+	}
+
+	if !errors.Is(err, cheapcash.ErrNotExists) {
+		t.Errorf("expected %v, got %v", cheapcash.ErrNotExists, err)
+	}
+}

writer_test.go

@@ -1,6 +1,8 @@
 package cheapcash_test
 
 import (
+	"math/rand"
+	"strconv"
 	"sync"
 	"testing"
 
@@ -37,3 +39,18 @@ func TestWrite_Concurrency(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestWrite_Exists(t *testing.T) {
+	rand := strconv.Itoa(rand.Int())
+	c := cheapcash.Default()
+
+	err := c.Write(rand, []byte("value"))
+	if err != nil {
+		t.Error("an error was thrown:", err)
+	}
+
+	err = c.Write(rand, []byte("another value"))
+	if err != nil {
+		t.Error("an error was thrown:", err)
+	}
+}