Check required is added. (#4)

.github/workflows/go.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v3
       with:
-        go-version: 1.20
+        go-version: 1.20.5
 
     - name: Go vet
       run: go vet ./...

check_required.go

@@ -0,0 +1,19 @@
+package checker
+
+import "reflect"
+
+const ResultRequired Result = "REQUIRED"
+
+func checkRequired(value reflect.Value) Result {
+	if value.IsZero() {
+		return ResultRequired
+	}
+
+	k := value.Kind()
+
+	if (k == reflect.Array || k == reflect.Map || k == reflect.Slice) && value.Len() == 0 {
+		return ResultRequired
+	}
+
+	return ResultValid
+}

check_required_test.go

@@ -0,0 +1,104 @@
+package checker
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestCheckRequiredValidString(t *testing.T) {
+	s := "valid"
+
+	if checkRequired(reflect.ValueOf(s)) != ResultValid {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredUninitializedString(t *testing.T) {
+	var s string
+
+	if checkRequired(reflect.ValueOf(s)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredEmptyString(t *testing.T) {
+	s := ""
+
+	if checkRequired(reflect.ValueOf(s)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredUninitializedNumber(t *testing.T) {
+	var n int
+
+	if checkRequired(reflect.ValueOf(n)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredValidSlice(t *testing.T) {
+	s := []int{1}
+
+	if checkRequired(reflect.ValueOf(s)) != ResultValid {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredUninitializedSlice(t *testing.T) {
+	var s []int
+
+	if checkRequired(reflect.ValueOf(s)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredEmptySlice(t *testing.T) {
+	s := make([]int, 0)
+
+	if checkRequired(reflect.ValueOf(s)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredValidArray(t *testing.T) {
+	s := [1]int{1}
+
+	if checkRequired(reflect.ValueOf(s)) != ResultValid {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredEmptyArray(t *testing.T) {
+	s := [1]int{}
+
+	if checkRequired(reflect.ValueOf(s)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredValidMap(t *testing.T) {
+	m := map[string]string{
+		"a": "b",
+	}
+
+	if checkRequired(reflect.ValueOf(m)) != ResultValid {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredUninitializedMap(t *testing.T) {
+	var m map[string]string
+
+	if checkRequired(reflect.ValueOf(m)) != ResultRequired {
+		t.Fail()
+	}
+}
+
+func TestCheckRequiredEmptyMap(t *testing.T) {
+	m := map[string]string{}
+
+	if checkRequired(reflect.ValueOf(m)) != ResultRequired {
+		t.Fail()
+	}
+}

checker.go

@@ -1,2 +1,14 @@
 // Package checker is a Go library for validating user input through struct tags.
 package checker
+
+// Result is a unique textual identifier for the mistake.
+type Result string
+
+// ResultValid result indicates that the user input is valid.
+const ResultValid Result = "VALID"
+
+// Mistake provides the field where the mistake was made and a result for the mistake.
+type Mistake struct {
+	Field  string
+	Result Result
+}