test(file): add tests with tempfile

tests/from_file.rs

@@ -1,14 +1,14 @@
 use filecaster::FromFile;
 
 #[derive(Debug, Clone, PartialEq, FromFile)]
-struct Simple {
+pub struct Simple {
     x: i32,
     #[from_file(default = "hello")]
     y: String,
 }
 
 #[derive(Debug, Clone, PartialEq, FromFile)]
-struct NumericDefault {
+pub struct NumericDefault {
     a: i32,
     #[from_file(default = 42)]
     b: i32,

tests/from_file_io.rs

@@ -0,0 +1,141 @@
+use filecaster::FromFile;
+use std::{fs::File, io::Write};
+use tempfile::NamedTempFile;
+
+#[derive(Debug, Clone, PartialEq, FromFile)]
+pub struct Simple {
+    x: i32,
+    #[from_file(default = "hello")]
+    y: String,
+}
+
+#[derive(Debug, Clone, PartialEq, FromFile)]
+pub struct NumericDefault {
+    a: i32,
+    #[from_file(default = 42)]
+    b: i32,
+}
+
+#[test]
+fn test_json_tempfile_full() {
+    let json = r#"{"x": 2, "y": "temp"}"#;
+    let mut tmp = NamedTempFile::new().unwrap();
+    write!(tmp.as_file_mut(), "{}", json).unwrap();
+
+    let file = File::open(tmp.path()).unwrap();
+    let file_struct: SimpleFile = serde_json::from_reader(file).unwrap();
+    let s = Simple::from_file(Some(file_struct));
+
+    assert_eq!(
+        s,
+        Simple {
+            x: 2,
+            y: "temp".to_string()
+        }
+    );
+}
+
+#[test]
+fn test_json_tempfile_partial() {
+    let json = r#"{"x": 5}"#;
+    let mut tmp = NamedTempFile::new().unwrap();
+    write!(tmp.as_file_mut(), "{}", json).unwrap();
+
+    let file = File::open(tmp.path()).unwrap();
+    let file_struct: SimpleFile = serde_json::from_reader(file).unwrap();
+    let s = Simple::from_file(Some(file_struct));
+
+    assert_eq!(
+        s,
+        Simple {
+            x: 5,
+            y: "hello".to_string()
+        }
+    );
+}
+
+#[test]
+fn test_toml_tempfile_full() {
+    let toml_str = r#"
+        x = 7
+        y = "toml_test"
+    "#;
+    let mut tmp = NamedTempFile::new().unwrap();
+    write!(tmp.as_file_mut(), "{}", toml_str).unwrap();
+
+    let content = std::fs::read_to_string(tmp.path()).unwrap();
+    let file_struct: SimpleFile = toml::from_str(&content).unwrap();
+    let s = Simple::from_file(Some(file_struct));
+
+    assert_eq!(
+        s,
+        Simple {
+            x: 7,
+            y: "toml_test".to_string()
+        }
+    );
+}
+
+#[test]
+fn test_toml_tempfile_partial() {
+    let toml_str = r#"x = 15"#;
+    let mut tmp = NamedTempFile::new().unwrap();
+    write!(tmp.as_file_mut(), "{}", toml_str).unwrap();
+
+    let content = std::fs::read_to_string(tmp.path()).unwrap();
+    let file_struct: SimpleFile = toml::from_str(&content).unwrap();
+    let s = Simple::from_file(Some(file_struct));
+
+    assert_eq!(
+        s,
+        Simple {
+            x: 15,
+            y: "hello".to_string()
+        }
+    );
+}
+
+#[test]
+fn test_numeric_default_toml() {
+    let toml_str = r#"a = 100"#;
+    let mut tmp = NamedTempFile::new().unwrap();
+    write!(tmp.as_file_mut(), "{}", toml_str).unwrap();
+
+    let content = std::fs::read_to_string(tmp.path()).unwrap();
+    let file_struct: NumericDefaultFile = toml::from_str(&content).unwrap();
+    let n = NumericDefault::from_file(Some(file_struct));
+
+    assert_eq!(n, NumericDefault { a: 100, b: 42 });
+}
+
+#[cfg(feature = "merge")]
+#[test]
+fn test_merge_from_toml() {
+    use merge::Merge;
+    let toml1 = r#"x = 1"#;
+    let toml2 = r#"y = "merged""#;
+
+    let mut tmp1 = NamedTempFile::new().unwrap();
+    write!(tmp1.as_file_mut(), "{}", toml1).unwrap();
+    let content1 = std::fs::read_to_string(tmp1.path()).unwrap();
+    let mut f1: SimpleFile = toml::from_str(&content1).unwrap();
+
+    let mut tmp2 = NamedTempFile::new().unwrap();
+    write!(tmp2.as_file_mut(), "{}", toml2).unwrap();
+    let content2 = std::fs::read_to_string(tmp2.path()).unwrap();
+    let f2: SimpleFile = toml::from_str(&content2).unwrap();
+
+    f1.merge(f2);
+    assert_eq!(f1.x, Some(1));
+    assert_eq!(f1.y, Some("merged".to_string()));
+
+    // Finally convert into the real struct
+    let s = Simple::from_file(Some(f1));
+    assert_eq!(
+        s,
+        Simple {
+            x: 1,
+            y: "merged".to_string()
+        }
+    );
+}