3 files changed, 233 insertions, 90 deletions
diff --git a/molecule/default/tests/test_check_prometheus_targets.py b/molecule/default/tests/test_check_prometheus_targets.py
deleted file mode 100644
index b9024b4..0000000
--- a/molecule/default/tests/test_check_prometheus_targets.py
+++ /dev/null
@@ -1,90 +0,0 @@
-testinfra_hosts = ["prometheus"]
-
-"""
-Test functionality of defining exporters and default fallbacks
-"""
-
-
-def test_check_hosts_added_simple(host):
-    t1 = host.file("/opt/simple_target1.yml")
-    t2 = host.file("/opt/simple_target2.yml")
-    t3 = host.file("/opt/simple_target3.yml")
-    t4 = host.file("/opt/simple_target4.yml")
-
-    assert t1.exists
-    assert t2.exists
-    assert t3.exists
-    assert t4.exists
-
-    assert t1.content_string == "    - application\n"
-
-    assert t2.content_string == "    - test1\n    - test2\n"
-
-    assert t3.content_string == "    - application_AA\n"
-
-    assert t4.content_string == "    - exporter_without_id\n"
-
-
-"""
-Test prefix functionality
-"""
-
-
-def test_check_hosts_added_prefix(host):
-    t1 = host.file("/opt/prefix_target1.yml")
-    t2 = host.file("/opt/prefix_target2.yml")
-    t3 = host.file("/opt/prefix/prefix_target3.yml")
-
-    assert t1.exists
-    assert t2.exists
-    assert t3.exists
-
-    assert t1.content_string == "    - application\n"
-
-    assert t2.content_string == "    - application\n"
-
-    assert t3.content_string == "    - application\n"
-
-
-"""
-Test hook functionality
-"""
-
-
-def test_check_hosts_added_hooks(host):
-    t1 = host.file("/opt/hook_target.yml")
-    t2 = host.file("/opt/hook1")
-    t3 = host.file("/opt/hook2")
-
-    assert t1.exists
-    assert t2.exists
-    assert t3.exists
-
-    assert (
-        t1.content_string == "    - application\n    - application2\n"
-        or t1.content_string == "    - application2\n    - application\n"
-    )
-
-    assert t3.content_string == "hello\nhello\n"
-
-
-"""
-Test lineinfile strategy parameters
-"""
-
-
-def test_check_host_added_lineinfile(host):
-    t1 = host.file("/opt/lineinfile.yml")
-
-    assert t1.user == "prometheus"
-    assert t1.group == "prometheus"
-    assert t1.mode == 0o600
-
-    assert (
-        t1.content_string == "- labels:\n"
-        "    my: label\n"
-        "  targets:\n"
-        "  - existing:9100\n"
-        "  - application:9100\n"
-    )
-
diff --git a/molecule/default/tests/test_lineinfile_strategy.py b/molecule/default/tests/test_lineinfile_strategy.py
new file mode 100644
index 0000000..b75a656
--- /dev/null
+++ b/molecule/default/tests/test_lineinfile_strategy.py
@@ -0,0 +1,94 @@
+import yaml
+
+
+testinfra_hosts = ["prometheus"]
+
+
+def read_file(host, path):
+    target = host.file(path)
+    assert target.exists
+    return target
+
+
+def read_yaml_file(host, path):
+    return yaml.safe_load(read_file(host, path).content_string)
+
+
+def test_lineinfile_bootstrap_adds_first_host_without_breaking_yaml(host):
+    target = read_file(host, "/opt/lineinfile_first_host.yml")
+
+    assert target.user == "prometheus"
+    assert target.group == "prometheus"
+    assert target.mode == 0o600
+    assert read_yaml_file(host, "/opt/lineinfile_first_host.yml") == ["application:9100"]
+
+
+def test_lineinfile_adds_subsequent_host_to_existing_yaml(host):
+    target = read_file(host, "/opt/lineinfile_bootstrap.yml")
+
+    assert target.content_string == (
+        "- labels:\n"
+        "    my: label\n"
+        "  targets:\n"
+        "  - existing:9100\n"
+        "  - application:9100\n"
+    )
+
+    assert read_yaml_file(host, "/opt/lineinfile_bootstrap.yml") == [
+        {"labels": {"my": "label"}, "targets": ["existing:9100", "application:9100"]}
+    ]
+
+
+def test_lineinfile_parallel_writes_keep_all_hosts_and_parse(host):
+    hosts = sorted(read_yaml_file(host, "/opt/lineinfile_parallel.yml"))
+    assert hosts == [
+        "application2:9100",
+        "application3:9100",
+        "application4:9100",
+        "application:9100",
+    ]
+
+
+def test_lineinfile_user_edited_file_stays_parseable(host):
+    target = read_file(host, "/opt/lineinfile_user_edited.yml")
+
+    assert target.content_string == (
+        "# user comment\n"
+        "- labels:\n"
+        "    env: prod\n"
+        "  targets:\n"
+        "  - existing:9100\n"
+        "  - application2:9100\n"
+    )
+
+    assert read_yaml_file(host, "/opt/lineinfile_user_edited.yml") == [
+        {"labels": {"env": "prod"}, "targets": ["existing:9100", "application2:9100"]}
+    ]
+
+
+def test_lineinfile_removing_last_host_still_leaves_parseable_yaml(host):
+    assert read_yaml_file(host, "/opt/lineinfile_remove_last.yml") == [
+        {"labels": {"env": "stage"}, "targets": None}
+    ]
+
+
+def test_lineinfile_compatibility_simple_and_prefix_cases(host):
+    assert read_yaml_file(host, "/opt/simple_target1.yml") == ["application"]
+    assert read_yaml_file(host, "/opt/simple_target2.yml") == ["test1", "test2"]
+    assert read_yaml_file(host, "/opt/simple_target3.yml") == ["application_AA"]
+    assert read_yaml_file(host, "/opt/simple_target4.yml") == ["exporter_without_id"]
+    assert read_yaml_file(host, "/opt/prefix_target1.yml") == ["application"]
+    assert read_yaml_file(host, "/opt/prefix_target2.yml") == ["application"]
+    assert read_yaml_file(host, "/opt/prefix/prefix_target3.yml") == ["application"]
+
+
+def test_lineinfile_hooks_still_run(host):
+    assert sorted(read_yaml_file(host, "/opt/hook_target.yml")) == [
+        "application",
+        "application2",
+        "application3",
+        "application4",
+    ]
+
+    assert host.file("/opt/hook1").exists
+    assert host.file("/opt/hook2").content_string == "hello\nhello\nhello\nhello\n"
diff --git a/molecule/default/tests/test_yaml_strategy.py b/molecule/default/tests/test_yaml_strategy.py
new file mode 100644
index 0000000..89dbdeb
--- /dev/null
+++ b/molecule/default/tests/test_yaml_strategy.py
@@ -0,0 +1,139 @@
+import yaml
+
+
+testinfra_hosts = ["prometheus"]
+
+
+def read_yaml_file(host, path):
+    target = host.file(path)
+    assert target.exists
+    return yaml.safe_load(target.content_string)
+
+
+def get_group_by_labels(groups, labels):
+    for group in groups:
+        if group.get("labels", {}) == labels:
+            return group
+    raise AssertionError(f"Missing target group with labels {labels!r}")
+
+
+def get_unlabeled_group(groups):
+    for group in groups:
+        if group.get("labels", {}) == {}:
+            return group
+    raise AssertionError("Missing unlabeled target group")
+
+
+def has_group_with_labels(groups, labels):
+    return any(group.get("labels", {}) == labels for group in groups)
+
+
+def test_yaml_bootstrap_adds_first_host_to_empty_file(host):
+    assert read_yaml_file(host, "/opt/yaml_bootstrap.yml") == [
+        {"labels": {"job": "node"}, "targets": ["application:9100"]}
+    ]
+
+
+def test_yaml_parallel_writes_keep_all_hosts_in_same_group(host):
+    groups = read_yaml_file(host, "/opt/yaml_parallel.yml")
+    assert get_group_by_labels(groups, {"job": "node"})["targets"] == [
+        "existing:9100",
+        "application:9100",
+        "application2:9100",
+        "application3:9100",
+        "application4:9100",
+    ]
+
+
+def test_yaml_user_edited_file_is_reparsed_and_keeps_expected_semantics(host):
+    groups = read_yaml_file(host, "/opt/yaml_user_edited.yml")
+
+    assert get_group_by_labels(groups, {"severity": "warning", "job": "external"})[
+        "targets"
+    ] == ["existing_host1:9100", "application2:9100"]
+
+    assert get_group_by_labels(groups, {"severity": "critical", "team": "blue"})[
+        "targets"
+    ] == ["application2:9200"]
+
+    assert get_unlabeled_group(groups)["targets"] == ["unlabeled:9100", "standalone:9300"]
+
+
+def test_yaml_moving_host_removes_last_host_from_old_group(host):
+    groups = read_yaml_file(host, "/opt/yaml_move_remove_last.yml")
+
+    assert not has_group_with_labels(groups, {"job": "old"})
+    assert get_group_by_labels(groups, {"job": "new"})["targets"] == ["application:9400"]
+
+
+def test_yaml_output_remains_parseable_after_all_operations(host):
+    for path in [
+        "/opt/yaml_bootstrap.yml",
+        "/opt/yaml_parallel.yml",
+        "/opt/yaml_user_edited.yml",
+        "/opt/yaml_move_remove_last.yml",
+        "/opt/yaml_branch_matrix.yml",
+        "/opt/yaml_missing_labeled.yml",
+        "/opt/yaml_missing_unlabeled.yml",
+    ]:
+        assert read_yaml_file(host, path) is not None
+
+
+def test_yaml_branch_matrix_covers_exact_match_and_append(host):
+    groups = read_yaml_file(host, "/opt/yaml_branch_matrix.yml")
+
+    assert get_group_by_labels(groups, {"job": "append", "env": "prod"})["targets"] == [
+        "existing_append:9500",
+        "application3:9506",
+    ]
+
+    assert get_group_by_labels(groups, {"job": "present", "env": "prod"})["targets"] == [
+        "application3:9501"
+    ]
+
+
+def test_yaml_branch_matrix_keeps_nonmatching_groups_for_both_label_mismatch_paths(host):
+    groups = read_yaml_file(host, "/opt/yaml_branch_matrix.yml")
+
+    assert get_group_by_labels(groups, {"job": "wrong", "env": "prod"})["targets"] == [
+        "keep_same_length:9500"
+    ]
+
+    assert get_group_by_labels(groups, {"job": "short"})["targets"] == [
+        "keep_length_mismatch:9500"
+    ]
+
+    assert get_group_by_labels(groups, {"job": "foreign"})["targets"] == ["foreign:9505"]
+
+
+def test_yaml_branch_matrix_moves_hosts_and_drops_emptied_groups(host):
+    groups = read_yaml_file(host, "/opt/yaml_branch_matrix.yml")
+
+    assert not has_group_with_labels(groups, {"job": "move_source"})
+
+    assert get_group_by_labels(groups, {"job": "move_target"})["targets"] == [
+        "application3:9502"
+    ]
+
+    assert get_group_by_labels(groups, {"job": "promoted"})["targets"] == [
+        "orphan_unlabeled:9503"
+    ]
+
+
+def test_yaml_branch_matrix_preserves_unlabeled_group_when_targets_remain(host):
+    groups = read_yaml_file(host, "/opt/yaml_branch_matrix.yml")
+
+    assert get_unlabeled_group(groups)["targets"] == [
+        "shared_unlabeled:9504",
+        "standalone_branch:9504",
+    ]
+
+
+def test_yaml_branch_matrix_creates_missing_file_groups_for_labeled_and_unlabeled_targets(host):
+    assert read_yaml_file(host, "/opt/yaml_missing_labeled.yml") == [
+        {"labels": {"team": "infra"}, "targets": ["application4:9600"]}
+    ]
+
+    assert read_yaml_file(host, "/opt/yaml_missing_unlabeled.yml") == [
+        {"targets": ["application4:9601"]}
+    ]