cmd/cue: add a test for embedding symbolic links

Valid symbolic links are currently allowed, but that will change
in the next commit. This test allows us to see the change in behavior.

While here, add more error test cases for embedding as well.
In particular, the "cannot embed directories" and invalid filetype
error code paths were not covered in the tests.

For #3299.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I5f80b1dc81e2a2bd13bd084be74cabec6f205ba4
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1199032
Unity-Result: CUE porcuepine <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>

cmd/cue/cmd/testdata/script/embed_err.txtar

@@ -1,9 +1,20 @@
 env CUE_EXPERIMENT=embed
 
 ! exec cue eval
-cmp stdout out/std
+! stdout .
 cmp stderr out/err
 
+# On systems with symlink support, check that we don't allow embedding symlinks.
+# TODO(mvdan): we don't reject valid symlinks yet; see https://cuelang.org/issue/3299.
+# TODO: if we support symlinks in the future, add a test case for a symlink pointing to a file
+# outside of the current module, as that should likely be forbidden.
+[!symlink] stop
+cd symlink
+symlink symlink.json -> test.json
+symlink symlink-parent.json -> ../test.json
+exec cue eval .
+cmp stdout out/std
+
 -- test.cue --
 @extern(embed)
 
@@ -59,6 +70,13 @@ unspecifiedFiletype4: _ @embed(glob=x/*.[j]son)
 nestedModJSON: _ @embed(file="a/b/foo.json")
 nestedModJSONWithGlob: _ @embed(glob="a/*/*.json")
 
+directory: _ @embed(file="x", type=cue)
+
+buildFailure: _ @embed(file="buildfail.cue")
+
+invalidFiletype: _ @embed(file="x.unknown")
+invalidPattern: _ @embed(glob="x[")
+
 -- test.json --
 { "x": 34 }
 -- test.ldjson --
@@ -83,12 +101,13 @@ a: 1
 x: 5
 -- xcue --
 x: 5
+-- buildfail.cue --
+x: 5 & >10
 -- a/b/cue.mod/modules.cue --
 module: "acme.com"
 language: version: "v0.9.0"
 -- a/b/foo.json --
 {"a": 1, "b": 2}
--- out/std --
 -- out/err --
 @embed: attribute must have file or glob field:
     ./test.cue:5:8
@@ -142,3 +161,36 @@ language: version: "v0.9.0"
     ./test.cue:52:18
 @embed: cannot embed file "a/b/foo.json": in different module:
     ./test.cue:53:26
+@embed: cannot embed directories:
+    ./test.cue:55:14
+@embed: encoding "cue" not (yet) supported:
+    ./test.cue:57:17
+@embed: unknown file extension .unknown:
+    ./test.cue:59:20
+@embed: invalid glob pattern "x[": syntax error in pattern:
+    ./test.cue:60:19
+-- symlink/test.cue --
+@extern(embed)
+
+package symlink
+
+file: _ @embed(file=symlink.json)
+
+glob: _ @embed(glob="*.json")
+-- symlink/test.json --
+{ "x": "symlink target file" }
+-- symlink/out/std --
+file: {
+    x: "symlink target file"
+}
+glob: {
+    "symlink-parent.json": {
+        x: 34
+    }
+    "symlink.json": {
+        x: "symlink target file"
+    }
+    "test.json": {
+        x: "symlink target file"
+    }
+}