The status code of every subprocess is checked

Every command will now print it's stderr to the terminal if it fails.
Previously the status code was not checked. _Creating_ the process was
checked (with expect or `?`) but the status code of the process on
completion was not.

src/build.rs

@@ -173,10 +173,11 @@ pub fn build(
     // Twine has too many dependencies to install when the environment, like we do with `wheel`, and
     // for now, it's easier to install using pip
     // todo: Install using own tools instead of pip; this is the last dependence on pip.
-    Command::new(paths.bin.join("python"))
+    let output = Command::new(paths.bin.join("python"))
         .args(&["-m", "pip", "install", "twine"])
-        .status()
+        .output()
         .expect("Problem installing Twine");
+    util::check_command_output(&output, "failed to install twine");
 
     //    let twine_url = "https://files.pythonhosted.org/packages/c4/43/b9c56d378f5d0b9bee7be564b5c5fb65c65e5da6e82a97b6f50c2769249a/twine-2.0.0-py3-none-any.whl";
     //    install::download_and_install_package(
@@ -197,10 +198,11 @@ pub fn build(
     println!("🛠️️ Building the package...");
     // todo: Run build script first, right?
     if let Some(build_file) = &cfg.build {
-        Command::new(paths.bin.join("python"))
+        let output = Command::new(paths.bin.join("python"))
             .arg(&build_file)
-            .status()
+            .output()
             .unwrap_or_else(|_| panic!("Problem building using {}", build_file));
+        util::check_command_output(&output, "failed to run build script");
     }
 
     //    Command::new(paths.bin.join("python"))
@@ -228,10 +230,11 @@ pub(crate) fn publish(bin_path: &PathBuf, cfg: &crate::Config) {
     };
 
     println!("Uploading to {}", repo_url);
-    Command::new(bin_path.join("twine"))
+    let output = Command::new(bin_path.join("twine"))
         .args(&["upload", "--repository-url", &repo_url, "dist/*"])
-        .status()
+        .output()
         .expect("Problem publishing");
+    util::check_command_output(&output, "publishing");
 }
 
 #[cfg(test)]

src/commands.rs

@@ -83,21 +83,23 @@ pub fn find_py_version(alias: &str) -> Option<crate::Version> {
 /// Additionally, create the __pypackages__ directory if not already created.
 pub fn create_venv(py_alias: &str, lib_path: &Path, name: &str) -> Result<(), Box<dyn Error>> {
     // While creating the lib path, we're creating the __pypackages__ structure.
-    Command::new(py_alias)
+    let output = Command::new(py_alias)
         .args(&["-m", "venv", name])
         .current_dir(lib_path.join("../"))
         .output()?;
+    util::check_command_output(&output, "creating virtual environment");
 
     Ok(())
 }
 
 // todo: DRY for using a path instead of str. use impl Into<PathBuf> ?
 pub fn create_venv2(py_alias: &Path, lib_path: &Path, name: &str) -> Result<(), Box<dyn Error>> {
     // While creating the lib path, we're creating the __pypackages__ structure.
-    Command::new(py_alias)
+    let output = Command::new(py_alias)
         .args(&["-m", "venv", name])
         .current_dir(lib_path.join("../"))
         .output()?;
+    util::check_command_output(&output, "creating virtual environment");
 
     Ok(())
 }
@@ -108,7 +110,8 @@ pub fn run_python(
     args: &[String],
 ) -> Result<(), Box<dyn Error>> {
     util::set_pythonpath(lib_paths);
-    Command::new(bin_path.join("python")).args(args).status()?;
+    let output = Command::new(bin_path.join("python")).args(args).output()?;
+    util::check_command_output(&output, "running python");
     Ok(())
 }
 
@@ -119,18 +122,20 @@ pub fn download_git_repo(repo: &str, dest_path: &Path) -> Result<(), Box<dyn Err
         util::abort("Can't find Git on the PATH. Is it installed?");
     }
 
-    Command::new("git")
+    let output = Command::new("git")
         .current_dir(dest_path)
         .args(&["clone", repo])
-        .status()?;
+        .output()?;
+    util::check_command_output(&output, "cloning repo");
     Ok(())
 }
 
 /// Initialize a new git repo.
 pub fn git_init(dir: &Path) -> Result<(), Box<dyn Error>> {
-    Command::new("git")
+    let output = Command::new("git")
         .current_dir(dir)
         .args(&["init", "--quiet"])
-        .status()?;
+        .output()?;
+    util::check_command_output(&output, "initializing git repository");
     Ok(())
 }

src/install.rs

@@ -351,38 +351,65 @@ pub fn download_and_install_package(
             replace_distutils(&extracted_parent.join("setup.py"));
 
             #[cfg(target_os = "windows")]
-            Command::new(paths.bin.join("python"))
-                .current_dir(&extracted_parent)
-                .args(&["setup.py", "bdist_wheel"])
-                .output()
-                .expect(&format!(
-                    "Problem running setup.py bdist_wheel in folder: {:?}. Py path: {:?}",
-                    &extracted_parent,
-                    paths.bin.join("python")
-                ));
-
+            {
+                let output = Command::new(paths.bin.join("python"))
+                    .current_dir(&extracted_parent)
+                    .args(&["setup.py", "bdist_wheel"])
+                    .output()
+                    .expect(&format!(
+                        "Problem running setup.py bdist_wheel in folder: {:?}. Py path: {:?}",
+                        &extracted_parent,
+                        paths.bin.join("python")
+                    ));
+                util::check_command_output_with(&output, |s| {
+                    panic!(
+                        "running setup.py bdist_wheel in folder {:?}. Py path: {:?}: {}",
+                        s
+                    )
+                });
+            }
             // The Linux and Mac builds appear to be unable to build wheels due to
             // missing the ctypes library; revert to system python.
             #[cfg(target_os = "linux")]
-            Command::new("python3")
-                .current_dir(&extracted_parent)
-                .args(&["setup.py", "bdist_wheel"])
-                .output()
-                .expect(&format!(
-                    "Problem running setup.py bdist_wheel in folder: {:?}. Py path: {:?}",
-                    &extracted_parent,
-                    paths.bin.join("python")
-                ));
+            {
+                let output = Command::new("python3")
+                    .current_dir(&extracted_parent)
+                    .args(&["setup.py", "bdist_wheel"])
+                    .output()
+                    .expect(&format!(
+                        "Problem running setup.py bdist_wheel in folder: {:?}. Py path: {:?}",
+                        &extracted_parent,
+                        paths.bin.join("python")
+                    ));
+                util::check_command_output_with(&output, |s| {
+                    panic!(
+                        "running setup.py bdist_wheel in folder {:?}. Py path: {:?}: {}",
+                        &extracted_parent,
+                        paths.bin.join("python"),
+                        s
+                    );
+                });
+            }
             #[cfg(target_os = "macos")]
-            Command::new("python3")
-                .current_dir(&extracted_parent)
-                .args(&["setup.py", "bdist_wheel"])
-                .output()
-                .expect(&format!(
-                    "Problem running setup.py bdist_wheel in folder: {:?}. Py path: {:?}",
-                    &extracted_parent,
-                    paths.bin.join("python")
-                ));
+            {
+                let output = Command::new("python3")
+                    .current_dir(&extracted_parent)
+                    .args(&["setup.py", "bdist_wheel"])
+                    .output()
+                    .expect(&format!(
+                        "Problem running setup.py bdist_wheel in folder: {:?}. Py path: {:?}",
+                        &extracted_parent,
+                        paths.bin.join("python")
+                    ));
+                util::check_command_output_with(&output, |s| {
+                    panic!(
+                        "running setup.py bdist_wheel in folder {:?}. Py path: {:?}: {}",
+                        &extracted_parent,
+                        paths.bin.join("python"),
+                        s
+                    );
+                });
+            }
 
             let dist_path = &extracted_parent.join("dist");
             if !dist_path.exists() {
@@ -621,13 +648,14 @@ pub fn download_and_install_git(
       //}
 
     // Build a wheel from the repo
-    Command::new(paths.bin.join("python"))
+    let output = Command::new(paths.bin.join("python"))
         // We assume that the module code is in the repo's immediate subfolder that has
         // the package's name.
         .current_dir(&git_path.join(&folder_name))
         .args(&["setup.py", "bdist_wheel"])
         .output()
         .expect("Problem running setup.py bdist_wheel");
+    util::check_command_output(&output, "running setup.py bdist_wheel");
 
     let archive_path = util::find_first_file(&git_path.join(folder_name).join("dist"));
     let filename = archive_path

src/util.rs

@@ -888,3 +888,21 @@ pub fn find_dont_uninstall(reqs: &[Req], dev_reqs: &[Req]) -> Vec<String> {
 
     result
 }
+
+// Internal function to handle error reporting for commands.
+//
+// Panics on subprocess failure printing error message
+pub(crate) fn check_command_output(output: &process::Output, msg: &str) {
+    check_command_output_with(output, |s| panic!("{}: {}", msg, s));
+}
+
+// Internal function to handle error reporting for commands.
+//
+// Panics on subprocess failure printing error message
+pub(crate) fn check_command_output_with(output: &process::Output, f: impl Fn(&str)) {
+    if !output.status.success() {
+        let stderr =
+            std::str::from_utf8(&output.stderr).expect("building string from command output");
+        f(&stderr)
+    }
+}