introduced content disposition in part

part.go

@@ -17,6 +17,7 @@ type Part struct {
 	contentType ContentType
 	charset     Charset
 	description string
+	disposition Disposition
 	encoding    Encoding
 	isDeleted   bool
 	writeFunc   func(io.Writer) (int64, error)
@@ -56,6 +57,11 @@ func (p *Part) GetDescription() string {
 	return p.description
 }
 
+// GetDisposition returns the currently set Content-Disposition of the Part
+func (p *Part) GetDisposition() Disposition {
+	return p.disposition
+}
+
 // SetContent overrides the content of the Part with the given string
 func (p *Part) SetContent(content string) {
 	buffer := bytes.NewBufferString(content)
@@ -82,6 +88,11 @@ func (p *Part) SetDescription(description string) {
 	p.description = description
 }
 
+// SetDisposition overrides the Content-Disposition of the Part
+func (p *Part) SetDisposition(disposition Disposition) {
+	p.disposition = disposition
+}
+
 // SetWriteFunc overrides the WriteFunc of the Part
 func (p *Part) SetWriteFunc(writeFunc func(io.Writer) (int64, error)) {
 	p.writeFunc = writeFunc
@@ -113,3 +124,10 @@ func WithPartContentDescription(description string) PartOption {
 		p.description = description
 	}
 }
+
+// WithContentDisposition overrides the default Part Content-Disposition
+func WithContentDisposition(disposition Disposition) PartOption {
+	return func(p *Part) {
+		p.disposition = disposition
+	}
+}

part_test.go

@@ -102,6 +102,35 @@ func TestPart_WithPartContentDescription(t *testing.T) {
 	}
 }
 
+// TestPart_withContentDisposition tests the WithContentDisposition method
+func TestPart_withContentDisposition(t *testing.T) {
+	tests := []struct {
+		name        string
+		disposition Disposition
+	}{
+		{"Part disposition: test", "test"},
+		{"Part disposition: empty", ""},
+	}
+	for _, tt := range tests {
+		m := NewMsg()
+		t.Run(tt.name, func(t *testing.T) {
+			part := m.newPart(TypeTextPlain, WithContentDisposition(tt.disposition), nil)
+			if part == nil {
+				t.Errorf("newPart() WithPartContentDescription() failed: no part returned")
+				return
+			}
+			if part.disposition != tt.disposition {
+				t.Errorf("newPart() WithContentDisposition() failed: expected: %s, got: %s", tt.disposition, part.description)
+			}
+			part.disposition = ""
+			part.SetDisposition(tt.disposition)
+			if part.disposition != tt.disposition {
+				t.Errorf("newPart() SetDisposition() failed: expected: %s, got: %s", tt.disposition, part.description)
+			}
+		})
+	}
+}
+
 // TestPartContentType tests Part.SetContentType
 func TestPart_SetContentType(t *testing.T) {
 	tests := []struct {
@@ -323,6 +352,31 @@ func TestPart_SetDescription(t *testing.T) {
 	}
 }
 
+// TestPart_SetDisposition tests Part.SetDisposition
+func TestPart_SetDisposition(t *testing.T) {
+	c := "This is a test"
+	d := Disposition("test-disposition")
+	m := NewMsg()
+	m.SetBodyString(TypeTextPlain, c)
+	pl, err := getPartList(m)
+	if err != nil {
+		t.Errorf("failed: %s", err)
+		return
+	}
+	pd := pl[0].GetDisposition()
+	if pd != "" {
+		t.Errorf("Part.GetDisposition failed. Expected empty description but got: %s", pd)
+	}
+	pl[0].SetDisposition(d)
+	if pl[0].disposition != d {
+		t.Errorf("Part.SetDisposition failed. Expected description to be: %s, got: %s", d, pd)
+	}
+	pd = pl[0].GetDisposition()
+	if pd != d {
+		t.Errorf("Part.GetDisposition failed. Expected: %s, got: %s", d, pd)
+	}
+}
+
 // TestPart_Delete tests Part.Delete
 func TestPart_Delete(t *testing.T) {
 	c := "This is a test with ümläutß"