From f05fae3ea31fa2d34e1f884f87a00d622764a14d Mon Sep 17 00:00:00 2001
From: Simon <s.thiessen@local-it.org>
Date: Tue, 27 Jan 2026 18:24:42 +0100
Subject: [PATCH] test: add tdd tests for groups administration #372

---
 docs/groups-architecture.md                   |   8 +-
 test/mv_web/live/group_live/form_test.exs     | 285 ++++++++++++++++++
 test/mv_web/live/group_live/index_test.exs    | 148 +++++++++
 .../live/group_live/integration_test.exs      | 209 +++++++++++++
 test/mv_web/live/group_live/show_test.exs     | 281 +++++++++++++++++
 test/support/fixtures.ex                      |  35 +++
 6 files changed, 962 insertions(+), 4 deletions(-)
 create mode 100644 test/mv_web/live/group_live/form_test.exs
 create mode 100644 test/mv_web/live/group_live/index_test.exs
 create mode 100644 test/mv_web/live/group_live/integration_test.exs
 create mode 100644 test/mv_web/live/group_live/show_test.exs

diff --git a/docs/groups-architecture.md b/docs/groups-architecture.md
index 023df5b..860d308 100644
--- a/docs/groups-architecture.md
+++ b/docs/groups-architecture.md
@@ -304,9 +304,9 @@ lib/
 - Add/remove groups inline
 - Link to group detail page
 
-### Group Detail View (`/groups/:id`)
+### Group Detail View (`/groups/:slug`)
 
-**Route:** `/groups/:id` - Group detail page (uses UUID, slug can be used for future `/groups/:slug` routes)
+**Route:** `/groups/:slug` - Group detail page (uses slug for URL-friendly routing)
 
 **Features:**
 - Display group name and description
@@ -315,7 +315,7 @@ lib/
 - Edit group button
 - Delete group button (with confirmation)
 
-**Note:** Currently uses UUID for routing. Slug is available for future URL-friendly routes (`/groups/:slug`).
+**Note:** Uses slug for routing to provide URL-friendly, readable group URLs (e.g., `/groups/board-members`).
 
 ### Accessibility (A11y) Considerations
 
@@ -1106,7 +1106,7 @@ Groups include automatic slug generation, following the same pattern as CustomFi
 - Automatically generated from the `name` attribute on create
 - Immutable after creation (don't change when name is updated)
 - Unique and URL-friendly
-- Available for future route enhancements (e.g., `/groups/:slug` instead of `/groups/:id`)
+- Used for routing (e.g., `/groups/:slug` for group detail pages)
 
 The implementation reuses the existing `GenerateSlug` change from CustomFields, ensuring consistency across the codebase.
 
diff --git a/test/mv_web/live/group_live/form_test.exs b/test/mv_web/live/group_live/form_test.exs
new file mode 100644
index 0000000..ceca883
--- /dev/null
+++ b/test/mv_web/live/group_live/form_test.exs
@@ -0,0 +1,285 @@
+defmodule MvWeb.GroupLive.FormTest do
+  @moduledoc """
+  Tests for the group create/edit form.
+
+  Tests cover:
+  - Creating groups
+  - Editing groups
+  - Form validations
+  - Edge cases
+  - Security
+  """
+  use MvWeb.ConnCase, async: false
+  import Phoenix.LiveViewTest
+  use Gettext, backend: MvWeb.Gettext
+
+  alias Mv.Fixtures
+
+  describe "create form" do
+    test "form renders with empty fields", %{conn: conn} do
+      {:ok, view, html} = live(conn, "/groups/new")
+
+      assert html =~ gettext("Create Group") || html =~ "create"
+      assert has_element?(view, "form")
+    end
+
+    test "creates group successfully with name and description", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "New Group",
+        "description" => "Group description"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # Should redirect to groups list or show page
+      assert_redirect(view, "/groups")
+    end
+
+    test "creates group successfully with name only (description optional)", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "Group Without Description"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      assert_redirect(view, "/groups")
+    end
+
+    test "shows error when name is missing", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "description" => "Description without name"
+      }
+
+      html =
+        view
+        |> form("form", group: form_data)
+        |> render_submit()
+
+      assert html =~ gettext("required") || html =~ "name" || html =~ "error"
+    end
+
+    test "shows error when name exceeds 100 characters", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      long_name = String.duplicate("a", 101)
+      form_data = %{"name" => long_name}
+
+      html =
+        view
+        |> form("form", group: form_data)
+        |> render_submit()
+
+      assert html =~ "100" || html =~ "length" || html =~ "error"
+    end
+
+    test "shows error when description exceeds 500 characters", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      long_description = String.duplicate("a", 501)
+      form_data = %{
+        "name" => "Test Group",
+        "description" => long_description
+      }
+
+      html =
+        view
+        |> form("form", group: form_data)
+        |> render_submit()
+
+      assert html =~ "500" || html =~ "length" || html =~ "error"
+    end
+
+    test "shows error when name already exists (case-insensitive)", %{conn: conn} do
+      _existing_group = Fixtures.group_fixture(%{name: "Existing Group"})
+
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "EXISTING GROUP"
+      }
+
+      html =
+        view
+        |> form("form", group: form_data)
+        |> render_submit()
+
+      assert html =~ "already" || html =~ "taken" || html =~ "exists" || html =~ "error"
+    end
+
+    test "shows error when name generates empty slug", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "!!!"
+      }
+
+      html =
+        view
+        |> form("form", group: form_data)
+        |> render_submit()
+
+      assert html =~ "error" || html =~ "invalid"
+    end
+  end
+
+  describe "edit form" do
+    test "form renders with existing group data", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Original Name", description: "Original Description"})
+
+      {:ok, view, html} = live(conn, "/groups/#{group.slug}/edit")
+
+      assert html =~ "Original Name"
+      assert html =~ "Original Description"
+      assert has_element?(view, "form")
+    end
+
+    test "updates group name successfully (slug remains unchanged)", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Original Name"})
+      original_slug = group.slug
+
+      {:ok, view, _html} = live(conn, "/groups/#{group.slug}/edit")
+
+      form_data = %{
+        "name" => "Updated Name"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # Verify slug didn't change by checking redirect URL or reloading
+      assert_redirect(view, "/groups/#{original_slug}")
+    end
+
+    test "updates group description successfully", %{conn: conn} do
+      group = Fixtures.group_fixture(%{description: "Old Description"})
+
+      {:ok, view, _html} = live(conn, "/groups/#{group.slug}/edit")
+
+      form_data = %{
+        "description" => "New Description"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      assert_redirect(view, "/groups/#{group.slug}")
+    end
+
+    test "shows error when updating to duplicate name (case-insensitive)", %{conn: conn} do
+      _group1 = Fixtures.group_fixture(%{name: "Group One"})
+      group2 = Fixtures.group_fixture(%{name: "Group Two"})
+
+      {:ok, view, _html} = live(conn, "/groups/#{group2.slug}/edit")
+
+      form_data = %{
+        "name" => "GROUP ONE"
+      }
+
+      html =
+        view
+        |> form("form", group: form_data)
+        |> render_submit()
+
+      assert html =~ "already" || html =~ "taken" || html =~ "exists" || html =~ "error"
+    end
+
+    test "slug is not displayed in form (immutable)", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Test Group"})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}/edit")
+
+      # Slug should not be in form (it's immutable)
+      refute html =~ ~r/slug.*input/i || html =~ ~r/input.*slug/i
+    end
+  end
+
+  describe "edge cases" do
+    test "handles whitespace trimming correctly", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "  Trimmed Group  "
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # Name should be trimmed
+      assert_redirect(view, "/groups")
+    end
+
+    test "handles umlauts in name correctly", %{conn: conn} do
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "Müller Gruppe"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      assert_redirect(view, "/groups")
+    end
+  end
+
+  describe "security" do
+    @tag role: :member
+    test "non-admin users cannot access create form", %{conn: conn} do
+      result = live(conn, "/groups/new")
+
+      assert match?({:error, {:redirect, %{to: _}}}, result) ||
+               match?({:error, {:live_redirect, %{to: _}}}, result)
+    end
+
+    @tag role: :member
+    test "non-admin users cannot access edit form", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      result = live(conn, "/groups/#{group.slug}/edit")
+
+      assert match?({:error, {:redirect, %{to: _}}}, result) ||
+               match?({:error, {:live_redirect, %{to: _}}}, result)
+    end
+
+    @tag role: :unauthenticated
+    test "unauthenticated users are redirected to login", %{conn: conn} do
+      result = live(conn, "/groups/new")
+
+      assert match?({:error, {:redirect, %{to: "/auth/sign_in"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/auth/sign_in"}}}, result)
+    end
+
+    test "user cannot edit group with non-existent slug", %{conn: conn} do
+      non_existent_slug = "non-existent-group-slug"
+
+      result = live(conn, "/groups/#{non_existent_slug}/edit")
+
+      assert match?({:error, {:redirect, %{to: "/groups"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/groups"}}}, result)
+    end
+
+    test "user cannot edit group with wrong slug (case mismatch)", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Test Group"})
+      wrong_case_slug = String.upcase(group.slug)
+
+      result = live(conn, "/groups/#{wrong_case_slug}/edit")
+
+      assert match?({:error, {:redirect, %{to: "/groups"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/groups"}}}, result)
+    end
+  end
+end
diff --git a/test/mv_web/live/group_live/index_test.exs b/test/mv_web/live/group_live/index_test.exs
new file mode 100644
index 0000000..c2c164f
--- /dev/null
+++ b/test/mv_web/live/group_live/index_test.exs
@@ -0,0 +1,148 @@
+defmodule MvWeb.GroupLive.IndexTest do
+  @moduledoc """
+  Tests for the groups overview page.
+
+  Tests cover:
+  - Displaying list of groups
+  - Creating new groups
+  - Deleting groups with confirmation
+  - Permission checks
+  - Edge cases
+  """
+  use MvWeb.ConnCase, async: false
+  import Phoenix.LiveViewTest
+  use Gettext, backend: MvWeb.Gettext
+
+  alias Mv.Membership
+  alias Mv.Fixtures
+
+  describe "mount and display" do
+    test "page renders successfully for admin user", %{conn: conn} do
+      {:ok, _view, html} = live(conn, "/groups")
+
+      assert html =~ gettext("Groups")
+    end
+
+    test "lists all groups", %{conn: conn} do
+      group1 = Fixtures.group_fixture(%{name: "Group One"})
+      group2 = Fixtures.group_fixture(%{name: "Group Two"})
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      assert html =~ group1.name
+      assert html =~ group2.name
+    end
+
+    test "displays group name, description, and member count", %{conn: conn} do
+      _group = Fixtures.group_fixture(%{name: "Test Group", description: "Test description"})
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      assert html =~ "Test Group"
+      assert html =~ "Test description"
+      # Member count should be displayed (0 for empty group)
+      assert html =~ "0" || html =~ gettext("Members")
+    end
+
+    test "displays 'Create Group' button for admin users", %{conn: conn} do
+      {:ok, _view, html} = live(conn, "/groups")
+
+      assert html =~ gettext("Create Group") || html =~ "create" || html =~ "new"
+    end
+
+    test "displays empty state when no groups exist", %{conn: conn} do
+      {:ok, _view, html} = live(conn, "/groups")
+
+      # Should show empty state or empty list message
+      assert html =~ gettext("No groups") || html =~ "0" || html =~ "empty"
+    end
+  end
+
+  describe "edge cases" do
+    test "handles very long group names correctly", %{conn: conn} do
+      long_name = String.duplicate("a", 100)
+      _group = Fixtures.group_fixture(%{name: long_name})
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      assert html =~ long_name
+    end
+
+    test "handles very long descriptions correctly", %{conn: conn} do
+      long_description = String.duplicate("a", 500)
+      _group = Fixtures.group_fixture(%{description: long_description})
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      assert html =~ long_description || html =~ String.slice(long_description, 0, 100)
+    end
+  end
+
+  describe "security" do
+    @tag role: :member
+    test "non-admin users cannot access groups page", %{conn: conn} do
+      # Should redirect or show 403
+      result = live(conn, "/groups")
+
+      assert match?({:error, {:redirect, %{to: _}}}, result) ||
+               match?({:error, {:live_redirect, %{to: _}}}, result)
+    end
+
+    @tag role: :unauthenticated
+    test "unauthenticated users are redirected to login", %{conn: conn} do
+      result = live(conn, "/groups")
+
+      assert match?({:error, {:redirect, %{to: "/auth/sign_in"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/auth/sign_in"}}}, result)
+    end
+
+    @tag role: :member
+    test "read-only users can view groups but not create", %{conn: conn} do
+      # Create read-only user
+      read_only_user = Fixtures.user_with_role_fixture("read_only")
+      conn = conn_with_password_user(conn, read_only_user)
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      # Should be able to see groups
+      assert html =~ gettext("Groups")
+
+      # Should NOT see create button
+      refute html =~ gettext("Create Group") || html =~ "create"
+    end
+  end
+
+  describe "performance" do
+    test "page loads efficiently with many groups", %{conn: conn} do
+      # Create multiple groups
+      Enum.each(1..10, fn _ -> Fixtures.group_fixture() end)
+
+      # Should load without N+1 queries
+      {:ok, _view, html} = live(conn, "/groups")
+
+      # Verify all groups are displayed
+      assert html =~ gettext("Groups")
+    end
+
+    test "member count is loaded efficiently via calculation", %{conn: conn} do
+      group = Fixtures.group_fixture()
+      member1 = Fixtures.member_fixture()
+      member2 = Fixtures.member_fixture()
+
+      # Add members to group
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+      Membership.create_member_group(%{member_id: member1.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      Membership.create_member_group(%{member_id: member2.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      # Member count should be displayed (should be 2)
+      assert html =~ "2" || html =~ gettext("Members")
+    end
+  end
+end
diff --git a/test/mv_web/live/group_live/integration_test.exs b/test/mv_web/live/group_live/integration_test.exs
new file mode 100644
index 0000000..4d58be1
--- /dev/null
+++ b/test/mv_web/live/group_live/integration_test.exs
@@ -0,0 +1,209 @@
+defmodule MvWeb.GroupLive.IntegrationTest do
+  @moduledoc """
+  Integration tests for complete group management workflows.
+
+  Tests cover:
+  - Complete workflows (Create → View → Edit → Delete)
+  - Slug-based navigation
+  - Member-group associations
+  - URL persistence
+  """
+  use MvWeb.ConnCase, async: false
+  import Phoenix.LiveViewTest
+  require Ash.Query
+  import Ash.Expr
+  use Gettext, backend: MvWeb.Gettext
+
+  alias Mv.Membership
+  alias Mv.Fixtures
+
+  describe "complete workflow" do
+    test "create → view via slug → edit → view via slug (slug unchanged)", %{
+      conn: conn,
+      current_user: current_user
+    } do
+      # Create group
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "Workflow Test Group",
+        "description" => "Initial description"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # Get the created group by name using current user (tests authorization)
+      {:ok, groups} = Membership.list_groups(actor: current_user)
+      group = Enum.find(groups, &(&1.name == "Workflow Test Group"))
+      original_slug = group.slug
+
+      # View via slug
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "Workflow Test Group"
+      assert html =~ "Initial description"
+
+      # Edit group
+      {:ok, view, _html} = live(conn, "/groups/#{group.slug}/edit")
+
+      form_data = %{
+        "name" => "Updated Workflow Test Group",
+        "description" => "Updated description"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # View again via slug (should still work with original slug)
+      {:ok, _view, html} = live(conn, "/groups/#{original_slug}")
+
+      assert html =~ "Updated Workflow Test Group"
+      assert html =~ "Updated description"
+      # Slug should remain unchanged
+      assert html =~ original_slug || html =~ "workflow-test-group"
+    end
+
+    test "create group → add members → view (member count updated)", %{
+      conn: conn,
+      current_user: current_user
+    } do
+      # Create group
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "Member Test Group"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # Get the created group using current user (tests authorization)
+      {:ok, groups} = Membership.list_groups(actor: current_user)
+      group = Enum.find(groups, &(&1.name == "Member Test Group"))
+
+      # Add members to group (use system_actor for test data setup)
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+      member1 = Fixtures.member_fixture()
+      member2 = Fixtures.member_fixture()
+
+      Membership.create_member_group(%{member_id: member1.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      Membership.create_member_group(%{member_id: member2.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      # View group via slug
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      # Member count should be 2
+      assert html =~ "2" || html =~ gettext("Members")
+      assert html =~ member1.first_name || html =~ member1.last_name
+      assert html =~ member2.first_name || html =~ member2.last_name
+    end
+
+    test "create group → add members → delete (cascade works)", %{
+      conn: conn,
+      current_user: current_user
+    } do
+      # Create group
+      {:ok, view, _html} = live(conn, "/groups/new")
+
+      form_data = %{
+        "name" => "Delete Test Group"
+      }
+
+      view
+      |> form("form", group: form_data)
+      |> render_submit()
+
+      # Get the created group using current user (tests authorization)
+      {:ok, groups} = Membership.list_groups(actor: current_user)
+      group = Enum.find(groups, &(&1.name == "Delete Test Group"))
+
+      # Add member to group (use system_actor for test data setup)
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+      member = Fixtures.member_fixture()
+
+      Membership.create_member_group(%{member_id: member.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      # Delete group (via UI - would need delete confirmation modal test)
+      # For now, test via API that cascade works
+      # Use current_user to test authorization (admin can delete)
+      :ok = Membership.destroy_group(group, actor: current_user)
+
+      # Verify member still exists (use system_actor for verification - this is test verification, not user action)
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+      {:ok, member_reloaded} = Ash.get(Mv.Membership.Member, member.id, actor: system_actor)
+      assert member_reloaded != nil
+
+      # Verify member-group association is deleted
+      {:ok, mgs} =
+        Ash.read(
+          Mv.Membership.MemberGroup
+          |> Ash.Query.filter(expr(group_id == ^group.id)),
+          actor: system_actor,
+          domain: Mv.Membership
+        )
+
+      assert mgs == []
+    end
+  end
+
+  describe "slug-based navigation" do
+    test "links to group detail use slug (not ID)", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Navigation Test Group"})
+
+      {:ok, _view, html} = live(conn, "/groups")
+
+      # Links should use slug, not UUID
+      assert html =~ "/groups/#{group.slug}"
+      refute html =~ "/groups/#{group.id}"
+    end
+
+    test "deep links to group detail per slug work", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Deep Link Test"})
+
+      # Direct navigation to slug URL
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "Deep Link Test"
+    end
+
+    test "browser back button works correctly", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      # Navigate to group detail
+      {:ok, _view1, _html} = live(conn, "/groups/#{group.slug}")
+
+      # Navigate to edit
+      {:ok, view2, _html} = live(conn, "/groups/#{group.slug}/edit")
+
+      # Browser back should work (tested via navigation)
+      assert view2 != nil
+    end
+  end
+
+  describe "URL persistence" do
+    test "slug-based URLs persist across page reloads", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Persistent URL Test"})
+
+      # First visit
+      {:ok, _view1, html1} = live(conn, "/groups/#{group.slug}")
+
+      assert html1 =~ "Persistent URL Test"
+
+      # Simulate page reload (new connection)
+      {:ok, _view2, html2} = live(conn, "/groups/#{group.slug}")
+
+      assert html2 =~ "Persistent URL Test"
+    end
+  end
+end
diff --git a/test/mv_web/live/group_live/show_test.exs b/test/mv_web/live/group_live/show_test.exs
new file mode 100644
index 0000000..bf94e85
--- /dev/null
+++ b/test/mv_web/live/group_live/show_test.exs
@@ -0,0 +1,281 @@
+defmodule MvWeb.GroupLive.ShowTest do
+  @moduledoc """
+  Tests for the group detail page.
+
+  Tests cover:
+  - Displaying group information
+  - Slug-based routing
+  - Member list display
+  - Navigation
+  - Error handling
+  - Delete functionality
+  """
+  use MvWeb.ConnCase, async: false
+  import Phoenix.LiveViewTest
+  require Ash.Query
+  use Gettext, backend: MvWeb.Gettext
+
+  alias Mv.Membership
+  alias Mv.Fixtures
+
+  describe "mount and display" do
+    test "page renders successfully", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ group.name
+    end
+
+    test "displays group name", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Test Group Name"})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "Test Group Name"
+    end
+
+    test "displays group description when present", %{conn: conn} do
+      group = Fixtures.group_fixture(%{description: "This is a test description"})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "This is a test description"
+    end
+
+    test "displays member count", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      # Member count should be displayed (might be 0 or more)
+      assert html =~ "0" || html =~ gettext("Members") || html =~ "member"
+    end
+
+    test "displays list of members in group", %{conn: conn} do
+      group = Fixtures.group_fixture()
+      member1 = Fixtures.member_fixture(%{first_name: "Alice", last_name: "Smith"})
+      member2 = Fixtures.member_fixture(%{first_name: "Bob", last_name: "Jones"})
+
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+      Membership.create_member_group(%{member_id: member1.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      Membership.create_member_group(%{member_id: member2.id, group_id: group.id},
+        actor: system_actor
+      )
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "Alice" || html =~ "Smith"
+      assert html =~ "Bob" || html =~ "Jones"
+    end
+
+    test "displays edit button for admin users", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ gettext("Edit") || html =~ "edit"
+    end
+
+    test "displays delete button for admin users", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ gettext("Delete") || html =~ "delete"
+    end
+  end
+
+  describe "slug-based routing" do
+    test "route /groups/:slug works correctly", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Board Members"})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "Board Members"
+      # Verify slug is in URL
+      assert html =~ group.slug || html =~ "board-members"
+    end
+
+    test "group is found by slug via unique_slug identity", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Test Group"})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ group.name
+    end
+
+    test "non-existent slug returns 404", %{conn: conn} do
+      non_existent_slug = "non-existent-group-slug"
+
+      result = live(conn, "/groups/#{non_existent_slug}")
+
+      assert match?({:error, {:redirect, %{to: "/groups"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/groups"}}}, result)
+    end
+
+    test "slug is case-sensitive (exact match required)", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Test Group"})
+      # Slug should be lowercase
+      wrong_case_slug = String.upcase(group.slug)
+
+      result = live(conn, "/groups/#{wrong_case_slug}")
+
+      # Should not find group with wrong case
+      assert match?({:error, {:redirect, %{to: "/groups"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/groups"}}}, result)
+    end
+
+    test "URL is readable and user-friendly", %{conn: conn} do
+      group = Fixtures.group_fixture(%{name: "Board Members"})
+
+      {:ok, _view, _html} = live(conn, "/groups/#{group.slug}")
+
+      # URL should contain readable slug, not UUID
+      assert group.slug == "board-members"
+      refute String.contains?(group.slug, "-") == false
+    end
+  end
+
+  describe "edge cases" do
+    test "displays empty group correctly (0 members)", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "0" || html =~ gettext("No members") || html =~ "empty"
+    end
+
+    test "handles group without description correctly", %{conn: conn} do
+      group = Fixtures.group_fixture(%{description: nil})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      # Should not crash, description should be optional
+      assert html =~ group.name
+    end
+
+    test "handles slug with special characters correctly", %{conn: conn} do
+      # Create group with name that generates slug with hyphens
+      group = Fixtures.group_fixture(%{name: "Test-Group-Name"})
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ "Test-Group-Name" || html =~ group.name
+    end
+  end
+
+  describe "security" do
+    @tag role: :member
+    test "read-only users can view group detail page", %{conn: conn} do
+      group = Fixtures.group_fixture()
+      read_only_user = Fixtures.user_with_role_fixture("read_only")
+      conn = conn_with_password_user(conn, read_only_user)
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ group.name
+      # Should NOT see edit/delete buttons
+      refute html =~ gettext("Edit") || html =~ gettext("Delete")
+    end
+
+    @tag role: :unauthenticated
+    test "unauthenticated users are redirected to login", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      result = live(conn, "/groups/#{group.slug}")
+
+      assert match?({:error, {:redirect, %{to: "/auth/sign_in"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/auth/sign_in"}}}, result)
+    end
+
+    test "slug injection attempts are prevented", %{conn: conn} do
+      # Try to inject SQL or other malicious content in slug
+      malicious_slug = "'; DROP TABLE groups; --"
+
+      result = live(conn, "/groups/#{malicious_slug}")
+
+      # Should not execute SQL, should return 404 or error
+      assert match?({:error, {:redirect, %{to: "/groups"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/groups"}}}, result)
+    end
+
+    test "user cannot delete group with non-existent slug", %{conn: conn} do
+      # This test verifies that delete action (if accessed via URL manipulation)
+      # cannot be performed with non-existent slug
+      # Note: Actual delete functionality will be tested when delete modal is implemented
+      non_existent_slug = "non-existent-group-slug"
+
+      # Attempting to access show page with non-existent slug should fail
+      result = live(conn, "/groups/#{non_existent_slug}")
+
+      assert match?({:error, {:redirect, %{to: "/groups"}}}, result) ||
+               match?({:error, {:live_redirect, %{to: "/groups"}}}, result)
+    end
+  end
+
+  describe "performance" do
+    test "member list is loaded efficiently (no N+1 queries)", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      # Create multiple members
+      members = Enum.map(1..5, fn _ -> Fixtures.member_fixture() end)
+
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+      # Add all members to group
+      Enum.each(members, fn member ->
+        Membership.create_member_group(%{member_id: member.id, group_id: group.id},
+          actor: system_actor
+        )
+      end)
+
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      # All members should be displayed
+      Enum.each(members, fn member ->
+        assert html =~ member.first_name || html =~ member.last_name
+      end)
+    end
+
+    test "slug lookup is efficient (uses unique_slug index)", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      # Should use index for fast lookup
+      {:ok, _view, html} = live(conn, "/groups/#{group.slug}")
+
+      assert html =~ group.name
+    end
+  end
+
+  describe "navigation" do
+    test "back button navigates to groups list", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, view, _html} = live(conn, "/groups/#{group.slug}")
+
+      assert {:error, {:live_redirect, %{to: to}}} =
+               view
+               |> element("a[aria-label*='Back'], button[aria-label*='Back']")
+               |> render_click()
+
+      assert to == "/groups"
+    end
+
+    test "edit button navigates to edit form", %{conn: conn} do
+      group = Fixtures.group_fixture()
+
+      {:ok, view, _html} = live(conn, "/groups/#{group.slug}")
+
+      assert {:error, {:live_redirect, %{to: to}}} =
+               view
+               |> element("a[href*='edit'], button[href*='edit']")
+               |> render_click()
+
+      assert to == "/groups/#{group.slug}/edit"
+    end
+  end
+end
diff --git a/test/support/fixtures.ex b/test/support/fixtures.ex
index 23d4aa7..fd4166d 100644
--- a/test/support/fixtures.ex
+++ b/test/support/fixtures.ex
@@ -262,4 +262,39 @@ defmodule Mv.Fixtures do
       {:error, error} -> raise "Failed to create member: #{inspect(error)}"
     end
   end
+
+  @doc """
+  Creates a group with default or custom attributes.
+
+  Uses system_actor for authorization to bypass permission checks in tests.
+
+  ## Parameters
+    - `attrs` - Map or keyword list of attributes to override defaults
+
+  ## Returns
+    - Group struct
+
+  ## Examples
+
+      iex> group_fixture()
+      %Mv.Membership.Group{name: "Test Group", slug: "test-group", ...}
+
+      iex> group_fixture(%{name: "Board Members", description: "Board members group"})
+      %Mv.Membership.Group{name: "Board Members", slug: "board-members", ...}
+
+  """
+  def group_fixture(attrs \\ %{}) do
+    system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+    attrs
+    |> Enum.into(%{
+      name: "Test Group #{System.unique_integer([:positive])}",
+      description: "Test description"
+    })
+    |> Mv.Membership.create_group(actor: system_actor)
+    |> case do
+      {:ok, group} -> group
+      {:error, error} -> raise "Failed to create group: #{inspect(error)}"
+    end
+  end
 end