fix: check --target for every platform first

install.ps1

@@ -8,7 +8,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-$defaultInstallSha256 = "8cf8886b8332714c2a2bc690a831fa2dd4b42f6b9c19df63bc002383b3650c2e"
+$defaultInstallSha256 = "546d190d17449d7b25bcf981bd396645c194364f363a2d315380a043ca101e38"
 $maximumInstallerBytes = 2MB
 $installerExit = 0
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -3276,6 +3276,29 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
     failures: list[tuple[str, str]] = []
     installed_paths: list[Path] = []
 
+    # --target is checked for every platform before anything is written, as
+    # --installed-cores is below: EmuDeck installed 3.2 GB and only then was
+    # steamos refused for RetroArch, with no summary of what had landed.
+    target_lists: dict[str, dict] = {}
+    if args.target and not args.list_targets:
+        for plat_name, _bios_path in platforms:
+            targets = fetch_targets(plat_name)
+            if targets is None:
+                sys.exit(1)
+            target_lists[plat_name] = targets
+            if args.target not in targets:
+                print(f"Error: unknown target '{args.target}' for {plat_name}.",
+                      file=sys.stderr)
+                print(
+                    f"  available: {', '.join(sorted(targets))}" if targets
+                    else f"  {plat_name} publishes no target list",
+                    file=sys.stderr,
+                )
+                if len(platforms) > 1:
+                    print("  Nothing was installed. Name one platform with "
+                          "--platform to install it alone.", file=sys.stderr)
+                sys.exit(1)
+
     # Every check --installed-cores makes before anything is written: a
     # refusal for the second platform must not follow an install of the first.
     cores_found: dict[tuple[str, Path], list[str]] = {}
@@ -3348,7 +3371,9 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
                     target = board
                     print(f"  Board {board} detected (--every-board installs all boards)")
         if target:
-            targets = fetch_targets(plat_name)
+            targets = target_lists.get(plat_name)
+            if targets is None:
+                targets = fetch_targets(plat_name)
             if targets is None:
                 sys.exit(1)
             target_info = targets.get(target)

install.sh

@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="8cf8886b8332714c2a2bc690a831fa2dd4b42f6b9c19df63bc002383b3650c2e"
+DEFAULT_INSTALL_SHA256="546d190d17449d7b25bcf981bd396645c194364f363a2d315380a043ca101e38"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

tests/test_install_cores.py

@@ -334,6 +334,31 @@ class RefusedBeforeAnyInstall(unittest.TestCase):
         fetch.assert_not_called()
 
 
+class AnUnknownTargetStopsTheRunFirst(unittest.TestCase):
+    """EmuDeck installed 3.2 GB, then steamos was refused for RetroArch and
+    the run ended without a summary."""
+
+    def test_nothing_is_fetched_when_one_platform_lacks_the_target(self):
+        tmp = Path(tempfile.mkdtemp(dir=REPO_ROOT / "tmp"))
+        self.addCleanup(shutil.rmtree, tmp, True)
+        detected = [("emudeck", tmp / "bios"), ("retroarch", tmp / "system")]
+        lists = {"emudeck": {"steamos": {"cores": []}}, "retroarch": {"x86_64": {"cores": []}}}
+        with mock.patch.object(install, "detect_os", return_value="linux"), \
+                mock.patch.object(install, "detect_frontends", return_value=[]), \
+                mock.patch.object(install, "detect_platforms", return_value=detected), \
+                mock.patch.object(install, "fetch_targets", side_effect=lists.get), \
+                mock.patch.object(install, "fetch_manifest") as fetch, \
+                mock.patch.object(sys, "argv", ["install.py", "--target", "steamos", "--no-input"]), \
+                contextlib.redirect_stdout(io.StringIO()), \
+                contextlib.redirect_stderr(io.StringIO()) as err:
+            with self.assertRaises(SystemExit) as stop:
+                install.main()
+        self.assertEqual(stop.exception.code, 1)
+        self.assertIn("unknown target 'steamos' for retroarch", err.getvalue())
+        self.assertIn("Nothing was installed", err.getvalue())
+        fetch.assert_not_called()
+
+
 class _CoreRepository(FakeRepository):
     """The fake repository with the two maps and a portable RetroArch."""