cmd/cue: add test for bad path lookup

I have observed that `cue mod tidy` can fail when
looking up package paths that are not valid module
paths. This CL adds a test case for that error,
so we can fix it in a subsequent CL.

Signed-off-by: Roger Peppe <rogpeppe@gmail.com>
Change-Id: I9b0d08a0d578ff44b1938e6f9ce21e705ceb11b3
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1199211
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>

cmd/cue/cmd/script_test.go

@@ -28,6 +28,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -36,6 +37,7 @@ import (
 	"cuelabs.dev/go/oci/ociregistry/ociclient"
 	"cuelabs.dev/go/oci/ociregistry/ocimem"
 	"cuelabs.dev/go/oci/ociregistry/ociref"
+	"cuelabs.dev/go/oci/ociregistry/ociserver"
 	"github.com/google/shlex"
 	"github.com/rogpeppe/go-internal/goproxytest"
 	"github.com/rogpeppe/go-internal/gotooltest"
@@ -287,20 +289,43 @@ func TestScript(t *testing.T) {
 				if data, err := os.ReadFile(filepath.Join(e.WorkDir, "_registry"+regID+"_prefix")); err == nil {
 					prefix = strings.TrimSpace(string(data))
 				}
+				useProxy := false
+				proxyFile := filepath.Join(e.WorkDir, "_registry"+regID+"_proxy")
+				if data, err := os.ReadFile(proxyFile); err == nil {
+					useProxy, err = strconv.ParseBool(strings.TrimSpace(string(data)))
+					if err != nil {
+						return fmt.Errorf("invalid contents of proxy file %q: %v", proxyFile, err)
+					}
+				}
 				reg, err := registrytest.New(os.DirFS(registryDir), prefix)
 				if err != nil {
 					return fmt.Errorf("cannot start test registry server: %v", err)
 				}
+				e.Defer(reg.Close)
 				if prefix != "" {
 					prefix = "/" + prefix
 				}
+				regHost := reg.Host()
+				if useProxy {
+					// Use a proxy for the registry, mirroring the way that the Central Registry
+					// works.
+					proxyClient, err := ociclient.New(regHost, &ociclient.Options{
+						Insecure: true,
+					})
+					if err != nil {
+						return fmt.Errorf("cannot create oci proxy client")
+					}
+					reg2 := httptest.NewServer(ociserver.New(proxyClient, nil))
+					reg2URL, _ := url.Parse(reg2.URL)
+					regHost = reg2URL.Host
+					e.Defer(reg2.Close)
+				}
 				e.Vars = append(e.Vars,
-					"CUE_REGISTRY"+regID+"="+reg.Host()+prefix+"+insecure",
+					"CUE_REGISTRY"+regID+"="+regHost+prefix+"+insecure",
 					// This enables some tests to construct their own malformed
 					// CUE_REGISTRY values that still refer to the test registry.
-					"DEBUG_REGISTRY"+regID+"_HOST="+reg.Host(),
+					"DEBUG_REGISTRY"+regID+"_HOST="+regHost,
 				)
-				e.Defer(reg.Close)
 			}
 			return nil
 		},

cmd/cue/cmd/testdata/script/modtidy_badpath.txtar

@@ -0,0 +1,56 @@
+# When the module resolution logic queries a registry for possible
+# module matches, it tries many possible prefixes. Some prefixes
+# might not be legitimate repository names even though they
+# are OK to use as package names. In such a case, a registry
+# might not return a 404 error, but some other kind of error.
+# The OCI proxy is one such registry.
+
+# TODO fix this so it works OK.
+! exec cue mod tidy
+cmp stderr want-stderr
+
+# TODO enable these assertions.
+# cmp cue.mod/module.cue want-module
+# exec cue export
+# cmp stdout want-stdout
+
+-- want-stderr --
+failed to resolve "test.example/foo/BarBaz": module test.example/foo/BarBaz: invalid OCI request: name invalid: invalid repository name
+-- want-module --
+module: "cue.example@v0"
+language: {
+	version: "v0.9.2"
+}
+deps: {
+	"test.example/foo@v0": {
+		v:       "v0.0.1"
+		default: true
+	}
+}
+-- cue.mod/module.cue --
+module: "cue.example@v0"
+language: version: "v0.9.2"
+
+-- want-stdout --
+{
+    "self": "test.example/foo/BarBaz"
+}
+-- main.cue --
+package main
+
+// Note: test.example/foo/BarBaz is an illegal module path
+// (because it contains upper case) but is OK as a package path.
+import "test.example/foo/BarBaz"
+
+BarBaz
+
+-- _registry_proxy --
+true
+-- _registry/test.example_foo_v0.0.1/cue.mod/module.cue --
+module: "test.example/foo@v0"
+language: version: "v0.9.2"
+
+-- _registry/test.example_foo_v0.0.1/BarBaz/x.cue --
+package BarBaz
+
+self: "test.example/foo/BarBaz"