Clarify error message when executed binary not found

Closes scientific-python#236

spin/cmds/meson.py

@@ -480,8 +480,9 @@ def test(
 
     package = cfg.get("tool.spin.package", None)
     if package is None:
-        print(
-            "Please specify `package = packagename` under `tool.spin` section of `pyproject.toml`"
+        click.secho(
+            "Please specify `package = packagename` under `tool.spin` section of `pyproject.toml`",
+            fg="bright_red",
         )
         raise SystemExit(1)
 
@@ -503,7 +504,7 @@ def test(
             "Error: cannot generate coverage report for editable installs",
             fg="bright_red",
         )
-        raise SystemExit(-1)
+        raise SystemExit(1)
 
     build_cmd = _get_configured_command("build")
     if build_cmd:

spin/cmds/util.py

@@ -67,12 +67,16 @@ def run(
         print(f"Failed to launch `{cmd}`")
         sys.exit(-1)
     else:
-        p = subprocess.run(cmd, *args, **kwargs)
+        try:
+            p = subprocess.run(cmd, *args, **kwargs)
+        except FileNotFoundError:
+            click.secho(f"`{cmd[0]}` executable not found. Exiting.", fg="bright_red")
+            raise SystemExit(1) from None
         if p.returncode != 0 and sys_exit:
             # Output was suppressed, but the process failed, so print it anyway
             if output is False:
                 print(p.stdout.decode("utf-8"), end="")
-            sys.exit(p.returncode)
+            raise SystemExit(p.returncode)
         return p
 
 

spin/tests/test_util.py

@@ -0,0 +1,10 @@
+import pytest
+
+from spin.cmds import util
+
+
+def test_cmd_not_found(capsys):
+    with pytest.raises(SystemExit):
+        util.run(["gdb1", "-e", "script"])
+    output = capsys.readouterr()
+    assert "executable not found" in output.out