Add tests to make sure the publisher works as expected.

tools/ci-build/publisher/src/subcommand/upgrade_runtime_crates_version.rs

@@ -7,6 +7,7 @@ use crate::fs::Fs;
 use anyhow::{anyhow, bail, Context};
 use clap::Parser;
 use regex::Regex;
+use std::borrow::Cow;
 use std::path::{Path, PathBuf};
 
 #[derive(Parser, Debug)]
@@ -27,35 +28,42 @@ pub async fn subcommand_upgrade_runtime_crates_version(
         .with_context(|| format!("{} is not a valid semver version", &args.version))?;
     let fs = Fs::Real;
     let gradle_properties = read_gradle_properties(fs, &args.gradle_properties_path).await?;
+    let updated_gradle_properties = update_gradle_properties(&gradle_properties, &upgraded_version)
+        .with_context(|| {
+            format!(
+                "Failed to extract the expected runtime crates version from `{:?}`",
+                &args.gradle_properties_path
+            )
+        })?;
+    update_gradle_properties_file(
+        fs,
+        &args.gradle_properties_path,
+        updated_gradle_properties.as_ref(),
+    )
+    .await?;
+    Ok(())
+}
+
+fn update_gradle_properties<'a>(
+    gradle_properties: &'a str,
+    upgraded_version: &'a semver::Version,
+) -> Result<Cow<'a, str>, anyhow::Error> {
     let version_regex =
         Regex::new(r"(?P<field>smithy\.rs\.runtime\.crate\.version=)(?P<version>\d+\.\d+\.\d+.*)")
             .unwrap();
-    let current_version = version_regex.captures(&gradle_properties).ok_or_else(|| {
-        anyhow!(
-            "Failed to extract the expected runtime crates version from `{:?}`",
-            &args.gradle_properties_path
-        )
-    })?;
+    let current_version = version_regex
+        .captures(gradle_properties)
+        .ok_or_else(|| anyhow!("Failed to extract the expected runtime crates version"))?;
     let current_version = current_version.name("version").unwrap();
     let current_version = semver::Version::parse(current_version.as_str())
         .with_context(|| format!("{} is not a valid semver version", current_version.as_str()))?;
-    if current_version > upgraded_version
+    if &current_version > upgraded_version
         // Special version tag used on the `main` branch
         && current_version != semver::Version::parse("0.0.0-smithy-rs-head").unwrap()
     {
         bail!("Moving from {current_version} to {upgraded_version} would be a *downgrade*. This command doesn't allow it!");
     }
-    let updated_gradle_properties = version_regex.replace(
-        &gradle_properties,
-        format!("${{field}}{}", upgraded_version),
-    );
-    update_gradle_properties(
-        fs,
-        &args.gradle_properties_path,
-        updated_gradle_properties.as_ref(),
-    )
-    .await?;
-    Ok(())
+    Ok(version_regex.replace(gradle_properties, format!("${{field}}{}", upgraded_version)))
 }
 
 async fn read_gradle_properties(fs: Fs, path: &Path) -> Result<String, anyhow::Error> {
@@ -65,11 +73,32 @@ async fn read_gradle_properties(fs: Fs, path: &Path) -> Result<String, anyhow::E
     Ok(contents)
 }
 
-async fn update_gradle_properties(
+async fn update_gradle_properties_file(
     fs: Fs,
     path: &Path,
     contents: &str,
 ) -> Result<(), anyhow::Error> {
     fs.write_file(path, contents.as_bytes()).await?;
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::subcommand::upgrade_runtime_crates_version::update_gradle_properties;
+
+    #[test]
+    fn upgrading_works_with_actual_version() {
+        let gradle_properties = "smithy.rs.runtime.crate.version=0.54.2";
+        let version = semver::Version::new(0, 54, 3);
+        let updated = update_gradle_properties(gradle_properties, &version).unwrap();
+        assert_eq!("smithy.rs.runtime.crate.version=0.54.3", updated);
+    }
+
+    #[test]
+    fn upgrading_works_with_dummy_version() {
+        let gradle_properties = "smithy.rs.runtime.crate.version=0.0.0-smithy-rs-head";
+        let version = semver::Version::new(0, 54, 3);
+        let updated = update_gradle_properties(gradle_properties, &version).unwrap();
+        assert_eq!("smithy.rs.runtime.crate.version=0.54.3", updated);
+    }
+}