data_alchemist_json/
writer.rs

1use std::io::Error;
2
3use data_alchemist::writer::{OutputSink, OutputWriter};
4
5pub struct JsonWriter;
6
7pub struct JsonProperties {}
8
9impl<T> OutputWriter<T> for JsonWriter where T: serde::Serialize {
10    type Properties = JsonProperties;
11
12    fn write(data: T, sink: &dyn OutputSink, _: Self::Properties) -> Result<(), Error> {
13        let serialized = serde_json::to_vec(&data)?;
14        sink.write_data(&serialized)
15    }
16}
17
18
19#[cfg(test)]
20mod test {
21    use mockall::mock;
22    use mockall::predicate::eq;
23    use serde::Serialize;
24
25    use super::*;
26
27    mock! {
28        pub OutputSink {}
29
30        impl OutputSink for OutputSink {
31            fn write_data(&self, data: &[u8]) -> Result<(), Error>;
32        }
33    }
34
35    #[derive(Serialize, Debug, PartialEq)]
36    struct TestStruct {
37        name: String,
38        age: u32,
39    }
40
41    #[test]
42    fn given_valid_struct_should_serialize_and_write() {
43        // given        
44        let test_data = TestStruct {
45            name: "Alice".to_string(),
46            age: 30,
47        };
48        let expected_json = serde_json::to_vec(&test_data).unwrap();
49
50        let mut mock_sink = MockOutputSink::new();
51        mock_sink.expect_write_data()
52            .with(eq(expected_json.clone()))  // Ensure the serialized data is passed
53            .times(1)
54            .returning(|_| Ok(()));
55
56        // when
57        let result = JsonWriter::write(test_data, &mut mock_sink, JsonProperties {});
58
59        // then
60        assert!(result.is_ok());
61    }
62
63    #[test]
64    fn given_sink_write_error_should_return_error() {
65        // given        
66        let test_data = TestStruct {
67            name: "Bob".to_string(),
68            age: 42,
69        };
70
71        let mut mock_sink = MockOutputSink::new();
72        mock_sink.expect_write_data()
73            .times(1)
74            .returning(|_| Err(std::io::Error::from(std::io::ErrorKind::Other)));
75
76        // when
77        let result = JsonWriter::write(test_data, &mut mock_sink, JsonProperties {});
78
79        // then
80        assert!(result.is_err());
81    }
82}
data_alchemist_json/writer.rs

data_alchemist_json/
writer.rs
