gopls/internal/test/marker: reject "module testdata"

Updates golang/go#65406

Change-Id: I1ce4e4d94f118c4b51dc52d624d90e2f7e05f048
Reviewed-on: https://go-review.googlesource.com/c/tools/+/559457
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

gopls/internal/test/marker/marker_test.go

@@ -698,6 +698,15 @@ func loadMarkerTest(name string, content []byte) (*markerTest, error) {
 				return nil, fmt.Errorf("%s:%d: unwanted space before marker (// @)", file.Name, line)
 			}
 
+			// The 'go list' command doesn't work correct with modules named
+			// testdata", so don't allow it as a module name (golang/go#65406).
+			// (Otherwise files within it will end up in an ad hoc
+			// package, "command-line-arguments/$TMPDIR/...".)
+			if filepath.Base(file.Name) == "go.mod" &&
+				bytes.Contains(file.Data, []byte("module testdata")) {
+				return nil, fmt.Errorf("'testdata' is not a valid module name")
+			}
+
 			test.notes = append(test.notes, notes...)
 			test.files[file.Name] = file.Data
 		}

gopls/internal/test/marker/testdata/codeaction/extract-variadic-63287.txt

@@ -3,7 +3,7 @@ It is a regression test for bug #63287 in which
 the final paramater's "..." would go missing.
 
 -- go.mod --
-module testdata
+module example.com
 go 1.18
 
 -- a/a.go --

gopls/internal/test/marker/testdata/codeaction/inline.txt

@@ -1,7 +1,7 @@
 This is a minimal test of the refactor.inline code action.
 
 -- go.mod --
-module testdata/codeaction
+module example.com/codeaction
 go 1.18
 
 -- a/a.go --

gopls/internal/test/marker/testdata/codeaction/issue64558.txt

@@ -1,7 +1,7 @@
 Test of an inlining failure due to an ill-typed input program (#64558).
 
 -- go.mod --
-module testdata
+module example.com
 go 1.18
 
 -- a/a.go --

gopls/internal/test/marker/testdata/hover/methods.txt

@@ -9,7 +9,7 @@ Observe that:
 - only accessible methods are shown.
 
 -- go.mod --
-module testdata
+module example.com
 
 -- lib/lib.go --
 package lib
@@ -31,7 +31,7 @@ func (s *S) pb() {}
 -- a/a.go --
 package a
 
-import "testdata/lib"
+import "example.com/lib"
 
 var _ lib.I //@hover("I", "I", I)
 var _ lib.J //@hover("J", "J", J)
@@ -50,13 +50,13 @@ type I interface {
 func (lib.J) C()
 ```
 
-[`lib.I` on pkg.go.dev](https://pkg.go.dev/testdata/lib#I)
+[`lib.I` on pkg.go.dev](https://pkg.go.dev/example.com/lib#I)
 -- @J --
 ```go
 type J interface{ C() }
 ```
 
-[`lib.J` on pkg.go.dev](https://pkg.go.dev/testdata/lib#J)
+[`lib.J` on pkg.go.dev](https://pkg.go.dev/example.com/lib#J)
 -- @S --
 ```go
 type S struct{ I }
@@ -68,4 +68,4 @@ func (lib.J) C()
 func (s *lib.S) PA()
 ```
 
-[`lib.S` on pkg.go.dev](https://pkg.go.dev/testdata/lib#S)
+[`lib.S` on pkg.go.dev](https://pkg.go.dev/example.com/lib#S)

gopls/internal/test/marker/testdata/rename/doclink.txt

@@ -1,7 +1,7 @@
 This test checks that doc links are also handled correctly (golang/go#64495).
 
 -- go.mod --
-module testdata
+module example.com
 
 go 1.21
 
@@ -35,7 +35,7 @@ func (E[T]) Foo() {} //@rename("Foo", "Bar", EFooToEBar)
 -- b/b.go --
 package b
 
-import aa "testdata/a" //@rename("aa", "a", pkgRename)
+import aa "example.com/a" //@rename("aa", "a", pkgRename)
 
 // FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
 // reference pointer type [*aa.D]
@@ -124,8 +124,8 @@ func FooBar() {
 +// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PFF]
 -- @pkgRename/b/b.go --
 @@ -3 +3 @@
--import aa "testdata/a" //@rename("aa", "a", pkgRename)
-+import "testdata/a" //@rename("aa", "a", pkgRename)
+-import aa "example.com/a" //@rename("aa", "a", pkgRename)
++import "example.com/a" //@rename("aa", "a", pkgRename)
 @@ -5,3 +5,3 @@
 -// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
 -// reference pointer type [*aa.D]

gopls/internal/test/marker/testdata/signature/issue63804.txt

@@ -4,7 +4,7 @@ the server's Signature method never returns an actual error,
 so the best we can assert is that there is no result.
 
 -- go.mod --
-module testdata
+module example.com
 go 1.18
 
 -- a/a.go --

gopls/internal/test/marker/testdata/suggestedfix/issue65024.txt

@@ -1,11 +1,11 @@
-Regression test for #65024, "incorrect package qualification when
+Regression example.com for #65024, "incorrect package qualification when
 stubbing method in v2 module".
 
 The second test (a-a) ensures that we don't use path-based heuristics
 to guess the PkgName of an import.
 
 -- a/v2/go.mod --
-module testdata/a/v2
+module example.com/a/v2
 go 1.18
 
 -- a/v2/a.go --
@@ -18,7 +18,7 @@ type T struct {}
 -- a/v2/b/b.go --
 package b
 
-import "testdata/a/v2"
+import "example.com/a/v2"
 
 type B struct{}
 
@@ -40,7 +40,7 @@ var _ a.I = &B{} //@ suggestedfix("&B{}", re"does not implement", out)
 // It won't do to use it as an identifier.
 // The correct name is the one in the package decl,
 // which in this case is not what the path heuristic would guess.
-module testdata/a-a/v2
+module example.com/a-a/v2
 go 1.18
 
 -- a-a/v2/a.go --
@@ -61,12 +61,12 @@ var _ I = &B{} //@ suggestedfix("&B{}", re"does not implement", out2)
 
 -- a-a/v2/b/import-a-I.go --
 package b
-import "testdata/a-a/v2"
+import "example.com/a-a/v2"
 type I = a.I
 
 -- @out2/a-a/v2/b/b.go --
 @@ -3 +3,2 @@
-+import a "testdata/a-a/v2"
++import a "example.com/a-a/v2"
 +
 @@ -7 +9,5 @@
 +// F implements a.I.