Method update_manifest

tests/support/mod.rs:338–346

(
        &self,
        f: impl FnOnce(DocumentMut) -> Result<DocumentMut>,
    )

    }

    pub fn update_manifest(
        &self,
        f: impl FnOnce(DocumentMut) -> Result<DocumentMut>,
    ) -> Result<()> {
        let manifest = self.read_manifest()?;
        let manifest_path = self.root.join("Cargo.toml");
        fs::write(manifest_path, f(manifest)?.to_string())?;
        Ok(())
    }

    pub fn build_dir(&self) -> PathBuf {
        self.root().join("target")