test(v1.4.0-p2): add failing tests for milestones and columns

RED phase: 5 tests in test_collector.py (collect_milestones),
10 tests in test_display.py (render_milestones, parse_columns),
2 tests in test_exporter.py (milestones JSON), 7 tests in
test_cli.py (--milestones, --columns).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_collector.py

@@ -2,7 +2,10 @@
 
 from unittest.mock import MagicMock
 
-from gitea_dashboard.collector import RepoData, collect_all
+from gitea_dashboard.collector import (
+    RepoData,
+    collect_all,
+)
 
 
 def _make_repo(
@@ -311,3 +314,158 @@ class TestCollectAllFiltering:
         result_empty = collect_all(client, include=[])
 
         assert [r.name for r in result_empty] == [r.name for r in result_none]
+
+
+class TestCollectMilestones:
+    """Test collect_milestones function."""
+
+    def _setup_client(self, repo_names, milestones_by_repo=None):
+        """Create a mock client with repos and milestones."""
+        client = MagicMock()
+        client.get_repos.return_value = [
+            _make_repo(name=n, full_name=f"admin/{n}") for n in repo_names
+        ]
+
+        if milestones_by_repo is None:
+            milestones_by_repo = {}
+
+        def get_milestones_side_effect(owner, repo, state="all"):
+            return milestones_by_repo.get(repo, [])
+
+        client.get_milestones.side_effect = get_milestones_side_effect
+        return client
+
+    def test_collect_milestones_basic(self):
+        """2 repos with milestones returns flat list of MilestoneData."""
+        from gitea_dashboard.collector import MilestoneData, collect_milestones
+
+        client = self._setup_client(
+            ["repo-a", "repo-b"],
+            {
+                "repo-a": [
+                    {
+                        "title": "v1.0",
+                        "open_issues": 2,
+                        "closed_issues": 3,
+                        "due_on": None,
+                        "state": "open",
+                    },
+                ],
+                "repo-b": [
+                    {
+                        "title": "v2.0",
+                        "open_issues": 0,
+                        "closed_issues": 5,
+                        "due_on": "2026-04-01T00:00:00Z",
+                        "state": "closed",
+                    },
+                ],
+            },
+        )
+
+        result = collect_milestones(client)
+
+        assert len(result) == 2
+        assert all(isinstance(m, MilestoneData) for m in result)
+        assert result[0].repo_name == "repo-a"
+        assert result[0].title == "v1.0"
+        assert result[1].repo_name == "repo-b"
+
+    def test_collect_milestones_empty_repo(self):
+        """Repo without milestones produces no entries."""
+        from gitea_dashboard.collector import collect_milestones
+
+        client = self._setup_client(["empty-repo"], {"empty-repo": []})
+
+        result = collect_milestones(client)
+
+        assert result == []
+
+    def test_collect_milestones_progress_calculation(self):
+        """3 open + 7 closed = progress_pct 70."""
+        from gitea_dashboard.collector import collect_milestones
+
+        client = self._setup_client(
+            ["repo"],
+            {
+                "repo": [
+                    {
+                        "title": "v1.0",
+                        "open_issues": 3,
+                        "closed_issues": 7,
+                        "due_on": None,
+                        "state": "open",
+                    },
+                ],
+            },
+        )
+
+        result = collect_milestones(client)
+
+        assert result[0].progress_pct == 70
+
+    def test_collect_milestones_with_include_filter(self):
+        """Include filter is respected."""
+        from gitea_dashboard.collector import collect_milestones
+
+        client = self._setup_client(
+            ["gitea-dashboard", "infra"],
+            {
+                "gitea-dashboard": [
+                    {
+                        "title": "v1.0",
+                        "open_issues": 1,
+                        "closed_issues": 1,
+                        "due_on": None,
+                        "state": "open",
+                    },
+                ],
+                "infra": [
+                    {
+                        "title": "v2.0",
+                        "open_issues": 0,
+                        "closed_issues": 5,
+                        "due_on": None,
+                        "state": "closed",
+                    },
+                ],
+            },
+        )
+
+        result = collect_milestones(client, include=["dashboard"])
+
+        assert len(result) == 1
+        assert result[0].repo_name == "gitea-dashboard"
+
+    def test_collect_milestones_with_exclude_filter(self):
+        """Exclude filter is respected."""
+        from gitea_dashboard.collector import collect_milestones
+
+        client = self._setup_client(
+            ["gitea-dashboard", "old-fork"],
+            {
+                "gitea-dashboard": [
+                    {
+                        "title": "v1.0",
+                        "open_issues": 1,
+                        "closed_issues": 1,
+                        "due_on": None,
+                        "state": "open",
+                    },
+                ],
+                "old-fork": [
+                    {
+                        "title": "v2.0",
+                        "open_issues": 0,
+                        "closed_issues": 5,
+                        "due_on": None,
+                        "state": "closed",
+                    },
+                ],
+            },
+        )
+
+        result = collect_milestones(client, exclude=["fork"])
+
+        assert len(result) == 1
+        assert result[0].repo_name == "gitea-dashboard"