feat(loader): adding more tests for loader (#48)

adding more tests for loader

loader.go

@@ -75,7 +75,7 @@ func (l *loader) loadDiff(old, newT any) error {
 		if oElem.Type().Field(i).Anonymous {
 			// If the embedded field is a pointer, dereference it
 			if oElem.Field(i).Kind() == reflect.Ptr {
-				if !oElem.Field(i).IsNil() && !nElem.Field(i).IsNil() {
+				if !oElem.Field(i).IsNil() && !nElem.Field(i).IsNil() { // If both are not nil, we need to recursively call LoadDiff
 					if err := l.loadDiff(oElem.Field(i).Interface(), nElem.Field(i).Interface()); err != nil {
 						return err
 					}
@@ -107,9 +107,7 @@ func (l *loader) loadDiff(old, newT any) error {
 
 		// Compare the old and new fields.
 		//
-		// New fields take priority over old fields if they are provided.
-		//
-		// We calculate whether we should be updating the field based off the LoaderOption's provided.
+		// New fields take priority over old fields if they are provided based on the configuration.
 		if !nElem.Field(i).IsZero() || l.includeZeroValues {
 			oElem.Field(i).Set(nElem.Field(i))
 		} else if nElem.Field(i).Kind() == reflect.Ptr && nElem.Field(i).IsNil() && l.includeNilValues {

loader_test.go

@@ -46,6 +46,30 @@ func (s *loadDiffSuite) TestLoadDiff_Success() {
 	s.Equal(26, old.Age)
 }
 
+func (s *loadDiffSuite) TestLoadDiff_Success_Pointed_Fields() {
+	s.l.includeNilValues = true
+
+	type testStruct struct {
+		Name *string
+		Age  *int
+	}
+
+	old := testStruct{
+		Name: ptr("John"),
+		Age:  ptr(25),
+	}
+
+	n := testStruct{
+		Name: ptr("John Smith"),
+		Age:  ptr(26),
+	}
+
+	err := s.l.loadDiff(&old, &n)
+	s.NoError(err)
+	s.Equal("John Smith", *old.Name)
+	s.Equal(26, *old.Age)
+}
+
 func (s *loadDiffSuite) TestLoadDiff_Success_ZeroValue() {
 	type testStruct struct {
 		Name string
@@ -135,6 +159,69 @@ func (s *loadDiffSuite) TestLoadDiff_Success_EmbeddedStruct() {
 	s.Equal(24, old.Partner.Age)
 }
 
+func (s *loadDiffSuite) TestLoadDiff_Success_EmbeddedStruct_Reverse() {
+	type testStruct struct {
+		Name    string
+		Age     int
+		Partner *testStruct
+	}
+
+	old := testStruct{
+		Name: "John",
+		Age:  25,
+		Partner: &testStruct{
+			Name: "Sarah",
+			Age:  24,
+		},
+	}
+
+	n := testStruct{
+		Partner: &testStruct{
+			Name: "Sarah Thompson",
+			Age:  27,
+		},
+	}
+
+	err := s.l.loadDiff(&old, &n)
+	s.NoError(err)
+	s.Equal("John", old.Name)
+	s.Equal(25, old.Age)
+	s.Equal("Sarah Thompson", old.Partner.Name)
+	s.Equal(27, old.Partner.Age)
+}
+
+func (s *loadDiffSuite) TestLoadDiff_Success_EmbeddedStruct_NotPointed() {
+	type testEmbed struct {
+		Name string
+		Age  int
+	}
+
+	type testStruct struct {
+		Name    string
+		Age     int
+		Partner testEmbed
+	}
+
+	old := testStruct{
+		Name: "John",
+		Age:  25,
+	}
+
+	n := testStruct{
+		Partner: testEmbed{
+			Name: "Sarah",
+			Age:  24,
+		},
+	}
+
+	err := s.l.loadDiff(&old, &n)
+	s.NoError(err)
+	s.Equal("John", old.Name)
+	s.Equal(25, old.Age)
+	s.Equal("Sarah", old.Partner.Name)
+	s.Equal(24, old.Partner.Age)
+}
+
 func (s *loadDiffSuite) TestLoadDiff_Success_EmbeddedStructWithNewValue() {
 	type testStruct struct {
 		Name    string