_stream.py: Added missing machine readable error codes

In errors pertaining to failing to launch a shell with a buildtree.

Other related updates:

  - _frontend/cli.py: Propagate machine readable error codes in `bst shell`

    This command prefixes a reported error, so it rewraps the error into
    an AppError, this needs to propagate the originating machine readable
    error.

  - tests/integration/shell.py, tests/integration/shellbuildtrees.py:

    Updated to use new machine readable errors

4 files changed, 11 insertions, 12 deletions

diff --git a/src/buildstream/_frontend/cli.py b/src/buildstream/_frontend/cli.py
index 5e42bda68..ab06e8a8a 100644
--- a/src/buildstream/_frontend/cli.py
+++ b/src/buildstream/_frontend/cli.py
@@ -640,7 +640,7 @@ def shell(app, element, mount, isolate, build_, cli_buildtree, pull_, command):
                 pull_=pull_,
             )
         except BstError as e:
-            raise AppError("Error launching shell: {}".format(e), detail=e.detail) from e
+            raise AppError("Error launching shell: {}".format(e), detail=e.detail, reason=e.reason) from e
 
     # If there were no errors, we return the shell's exit code here.
     sys.exit(exitcode)
diff --git a/src/buildstream/_stream.py b/src/buildstream/_stream.py
index 0aff5fb94..e91ee882c 100644
--- a/src/buildstream/_stream.py
+++ b/src/buildstream/_stream.py
@@ -221,6 +221,7 @@ class Stream:
             raise StreamError(
                 "Elements need to be built or downloaded before staging a shell environment",
                 detail="\n".join(list(map(lambda x: x._get_full_name(), missing_deps))),
+                reason="shell-missing-deps",
             )
 
         # Check if we require a pull queue attempt, with given artifact state and context
@@ -229,11 +230,14 @@ class Stream:
                 remotes_message = " or in available remotes" if pull_ else ""
                 if not element._cached():
                     message = "Artifact not cached locally" + remotes_message
+                    reason = "missing-buildtree-artifact-not-cached"
                 elif element._buildtree_exists():
                     message = "Buildtree is not cached locally" + remotes_message
+                    reason = "missing-buildtree-artifact-buildtree-not-cached"
                 else:
                     message = "Artifact was created without buildtree"
-                raise StreamError(message)
+                    reason = "missing-buildtree-artifact-created-without-buildtree"
+                raise StreamError(message, reason=reason)
 
             # Raise warning if the element is cached in a failed state
             if element._cached_failure():
diff --git a/tests/integration/shell.py b/tests/integration/shell.py
index 42e486bac..a022d86be 100644
--- a/tests/integration/shell.py
+++ b/tests/integration/shell.py
@@ -393,7 +393,7 @@ def test_integration_partial_artifact(cli, datafiles, tmpdir, integration_cache)
 
         # check shell doesn't work
         result = cli.run(project=project, args=["shell", element_name, "--", "hello"])
-        result.assert_main_error(ErrorDomain.APP, None)
+        result.assert_main_error(ErrorDomain.APP, "shell-missing-deps")
 
         # check the artifact gets completed with '--pull' specified
         result = cli.run(project=project, args=["shell", "--pull", element_name, "--", "hello"])
diff --git a/tests/integration/shellbuildtrees.py b/tests/integration/shellbuildtrees.py
index 5164c0209..65b2d9fae 100644
--- a/tests/integration/shellbuildtrees.py
+++ b/tests/integration/shellbuildtrees.py
@@ -69,8 +69,7 @@ def test_buildtree_staged_warn_empty_cached(cli_integration, tmpdir, datafiles):
     res = cli_integration.run(
         project=project, args=["shell", "--build", "--use-buildtree", element_name, "--", "cat", "test"]
     )
-    res.assert_main_error(ErrorDomain.APP, None)
-    assert "Error launching shell: Artifact was created without buildtree" in res.stderr
+    res.assert_main_error(ErrorDomain.APP, "missing-buildtree-artifact-created-without-buildtree")
 
 
 @pytest.mark.datafiles(DATA_DIR)
@@ -109,8 +108,7 @@ def test_buildtree_from_failure_option_never(cli_integration, tmpdir, datafiles)
     res = cli_integration.run(
         project=project, args=["shell", "--build", element_name, "--use-buildtree", "--", "cat", "test"]
     )
-    res.assert_main_error(ErrorDomain.APP, None)
-    assert "Error launching shell: Artifact was created without buildtree" in res.stderr
+    res.assert_main_error(ErrorDomain.APP, "missing-buildtree-artifact-created-without-buildtree")
 
 
 @pytest.mark.datafiles(DATA_DIR)
@@ -229,9 +227,7 @@ def test_buildtree_options(cli, tmpdir, datafiles):
         result = cli.run(project=project, args=["artifact", "pull", "--deps", "all", element_name])
         result.assert_success()
         res = cli.run(project=project, args=["shell", "--build", element_name, "--use-buildtree", "--", "cat", "test"])
-        res.assert_main_error(ErrorDomain.APP, None)
-        assert "Buildtree is not cached locally" in res.stderr
-        assert "Hi" not in res.output
+        res.assert_main_error(ErrorDomain.APP, "missing-buildtree-artifact-buildtree-not-cached")
 
         # Check that when user context is set to pull buildtrees and a remote has the buildtree,
         # '--use-buildtree' will attempt and succeed at pulling the missing buildtree with --pull set.
@@ -278,8 +274,7 @@ def test_pull_buildtree_pulled(cli, tmpdir, datafiles):
             project=project,
             args=["shell", "--build", element_name, "--pull", "--use-buildtree", "--", "cat", "test",],
         )
-        res.assert_main_error(ErrorDomain.APP, None)
-        assert "Buildtree is not cached locally" in res.stderr
+        res.assert_main_error(ErrorDomain.APP, "missing-buildtree-artifact-buildtree-not-cached")
 
         # Check it's using the cached build tree, because --pull
         # and pull-buildtrees were both set