disk(new): add disk module with generic read/write functions

disk/disk.go

@@ -0,0 +1,39 @@
+package disk
+
+import (
+	"encoding/json"
+	"errors"
+	"io/fs"
+	"os"
+)
+
+func ReadJsonFile[E any](path string, obj *E) error {
+	if obj == nil {
+		return errors.New("obj is nil")
+	}
+
+	file, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	err = json.Unmarshal(file, obj)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func WriteJsonFile[E any](obj E, path string, perm fs.FileMode) error {
+	towrite, err := json.MarshalIndent(obj, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	err = os.WriteFile(path, towrite, perm)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

disk/disk_test.go

@@ -0,0 +1,52 @@
+package disk
+
+import (
+	"os"
+	"testing"
+)
+
+func TestJsonFile(t *testing.T) {
+	// test data
+	type testStruct struct {
+		A int
+		B string
+		C []int
+	}
+	testData := testStruct{
+		A: 1,
+		B: "test",
+		C: []int{1, 2, 3},
+	}
+	// write test data to file
+	err := WriteJsonFile[testStruct](testData, "../testdata/test.json", 0644)
+	if err != nil {
+		t.Error("Error writing file: ", err)
+	}
+	// read test data from file
+	var readData testStruct
+	err = ReadJsonFile[testStruct]("../testdata/test.json", &readData)
+	if err != nil {
+		t.Error("Error reading file: ", err)
+	}
+	// compare test data to read data
+	if testData.A != readData.A {
+		t.Errorf("TestJsonFile A = %d; want %d", readData.A, testData.A)
+	}
+	if testData.B != readData.B {
+		t.Errorf("TestJsonFile B = %s; want %s", readData.B, testData.B)
+	}
+	if len(testData.C) != len(readData.C) {
+		t.Errorf("TestJsonFile C = %d; want %d", len(readData.C), len(testData.C))
+	}
+	for i := range testData.C {
+		if testData.C[i] != readData.C[i] {
+			t.Errorf("TestJsonFile C[%d] = %d; want %d", i, readData.C[i], testData.C[i])
+		}
+	}
+
+	// clean up
+	err = os.Remove("../testdata/test.json")
+	if err != nil {
+		t.Error("Error removing file: ", err)
+	}
+}