tests/functional2: fix bad error message when merging files

The error message used to only contain the last key of the merge failure
this commit changes the message to contain the full path to the merge
conflict, resolving ambiguity

Change-Id: I9848a559b1b888e50a548eef8609bf34506040de

tests/functional2/testlib/fixtures/file_helper.py

@@ -146,9 +146,13 @@ def merge_file_declaration(a: FileDeclaration, b: FileDeclaration) -> FileDeclar
             result[key] = a.get(key) or b.get(key)
             continue
         if isinstance(a[key], Fileish) or isinstance(b[key], Fileish):
-            msg = "Cannot merge files; got two different values for the same path %s"
+            msg = "Cannot merge files; got two different values for the same path"
             raise ValueError(msg, key)
+        try:
             result[key] = merge_file_declaration(a[key], b[key])
+        except ValueError as e:
+            msg, path = e.args
+            raise ValueError(msg, f"{key}/{path}")
 
     return result
 

tests/functional2/testlib/fixtures/test_file_helper.py

@@ -9,6 +9,7 @@ from functional2.testlib.fixtures.file_helper import (
     File,
     Symlink,
     AssetSymlink,
+    merge_file_declaration,
 )
 
 
@@ -249,3 +250,39 @@ def test_file_symlink(files: Path):
     assert link.is_symlink()
     # check that this is actually relative and not an absolute path
     assert str(link.readlink()) == "../tg"
+
+
+def test_merge_fd_merges_correctly():
+    fa = File("a")
+    fc = File("c")
+    fd = File("d")
+    ff = File("f")
+    fd1 = {"a": fa, "b": {"c": fc}}
+
+    fd2 = {"b": {"d": fd}, "e": {"f": ff}}
+
+    expected = {"a": fa, "b": {"c": fc, "d": fd}, "e": {"f": ff}}
+
+    result = merge_file_declaration(fd1, fd2)
+    assert result == expected
+
+
+def test_merge_fd_throws_on_conflict():
+    fd1 = {"a": {"b": File("b")}}
+    fd2 = {"a": File("a")}
+
+    with pytest.raises(
+        ValueError, match="('Cannot merge files; got two different values for the same path', 'a')"
+    ):
+        merge_file_declaration(fd1, fd2)
+
+
+def test_merge_fd_throws_on_conflict_with_full_path():
+    fd1 = {"a": {"b": {"c": {"d": File("d")}}}}
+    fd2 = {"a": {"b": {"c": {"d": File("different file")}}}}
+
+    with pytest.raises(
+        ValueError,
+        match="('Cannot merge files; got two different values for the same path', 'a/b/c/d')",
+    ):
+        merge_file_declaration(fd1, fd2)