Change json serialization to use 4 spaces

Cargo.toml

@@ -22,6 +22,7 @@ nom = "6.1.0"
 notify = "4.0.15"
 atty = "0.2.14"
 anyhow = "1.0.38"
+serde = { version = "1.0.123", default-features = false }
 
 [dependencies.clap]
 version = "2.33.3"

src/init.rs

@@ -18,12 +18,8 @@ pub fn main<P: AsRef<Path>>(elm_home: P, project_root: P, offline: bool) -> anyh
     let updated_config = crate::deps::init(elm_home, project_config, offline).context(
         "Something went wrong when installing elm-explorations/test to the tests dependencies",
     )?;
-    std::fs::write(
-        &elm_json_path,
-        serde_json::to_string_pretty(&updated_config)
-            .context("Unable to convert the config to a JSON string")?,
-    )
-    .context("Unable to write the updated elm.json")?;
+    crate::utils::json_write(&elm_json_path, &updated_config)
+        .context("Unable to write the updated elm.json")?;
 
     // Create the tests/Tests.elm template
     let init_tests_template = include_template!("Tests.elm");

src/make.rs

@@ -236,6 +236,7 @@ pub fn main_helper(
         "Could not create tests dir {}",
         tests_root.join("src").display()
     ))?;
+    // If it has changed, update the elm.json for the tests.
     let tests_config_str = serde_json::to_string(&tests_config)
         .context("Failed to convert to JSON the string generated for the tests elm.json")?;
     match std::fs::read_to_string(&tests_config_path) {

src/utils.rs

@@ -2,6 +2,7 @@
 
 use anyhow::Context;
 use std::error::Error;
+use std::io::Write;
 use std::path::{Path, PathBuf};
 
 #[macro_export]
@@ -77,3 +78,19 @@ pub fn http_fetch(url: &str) -> Result<String, Box<dyn Error>> {
         .context("Error converting the http response body to a String")?;
     Ok(response)
 }
+
+// pub fn write_elm_json(project: &Project, matches: &ArgMatches) -> Result<()> {
+pub fn json_write<P: AsRef<Path>, T: ?Sized + serde::Serialize>(
+    path: P,
+    value: &T,
+) -> anyhow::Result<()> {
+    let path = path.as_ref();
+    let file = std::fs::File::create(path)?;
+    let writer = std::io::BufWriter::new(file);
+    let formatter = serde_json::ser::PrettyFormatter::with_indent(b"    ");
+    let mut serializer = serde_json::Serializer::with_formatter(writer, formatter);
+    value.serialize(&mut serializer)?;
+    let mut writer = serializer.into_inner();
+    writeln!(&mut writer)?;
+    writer.flush().map_err(|e| e.into())
+}