refactor: pattern-match over conditionals in Navigation and InsertOptimizer

Swaps `if`/`cond` branches for multi-clause function heads or head-pattern
matching, making the control flow visible in the function signatures:

- Navigation.determine_map_location: resolve_location/4 now dispatches on
  the shape of the geolocation input and whether URL params are explicit.
- Navigation.handle_callsign_tracking: per-case clauses for empty callsign
  and explicit-URL-params short-circuits, plus a final clause that does the
  DB lookup and rescues once.
- Navigation.handle_callsign_search: dispatch_callsign_search/3 separates
  the valid/invalid callsign branches.
- InsertOptimizer.optimize_based_on_performance: pattern-match on
  [_, _, _ | _] to require ≥3 samples without calling length/1.
- InsertOptimizer.calculate_insert_options and throughput helpers split
  into guarded clauses instead of inline `if`.
- maybe_emit_optimization uses same-var pattern matching to skip the
  telemetry hit when nothing changed.

Adds unit tests covering every branch of both modules plus SignalHandler,
LocaleHook, and the InsertOptimizer's :noproc fallback path. Coverage
64.69% → 65.72%.

lib/aprsme/performance/insert_optimizer.ex

@@ -75,14 +75,11 @@ defmodule Aprsme.Performance.InsertOptimizer do
 
   @impl true
   def handle_cast({:record_metrics, batch_size, duration_ms, success_count}, state) do
-    # Calculate throughput (packets per second)
-    throughput = if duration_ms > 0, do: success_count / (duration_ms / 1000), else: 0
-
     metric = %{
       batch_size: batch_size,
       duration_ms: duration_ms,
       success_count: success_count,
-      throughput: throughput,
+      throughput: throughput(success_count, duration_ms),
       timestamp: System.monotonic_time(:millisecond)
     }
 
@@ -92,6 +89,11 @@ defmodule Aprsme.Performance.InsertOptimizer do
     {:noreply, %{state | performance_history: new_history}}
   end
 
+  # Packets-per-second, or 0 when the batch completed instantly (avoid div-by-0).
+  defp throughput(_count, 0), do: 0
+  defp throughput(_count, duration_ms) when duration_ms < 0, do: 0
+  defp throughput(count, duration_ms), do: count / (duration_ms / 1000)
+
   @impl true
   def handle_info(:optimize_settings, state) do
     new_state = optimize_based_on_performance(state)
@@ -103,43 +105,44 @@ defmodule Aprsme.Performance.InsertOptimizer do
     Process.send_after(self(), :optimize_settings, @optimization_check_interval)
   end
 
-  defp optimize_based_on_performance(state) do
-    if length(state.performance_history) >= 3 do
-      # Analyze recent performance
-      recent_metrics = Enum.take(state.performance_history, 5)
-      total_throughput = recent_metrics |> Enum.map(& &1.throughput) |> Enum.sum()
-      avg_throughput = total_throughput / length(recent_metrics)
-      total_duration = recent_metrics |> Enum.map(& &1.duration_ms) |> Enum.sum()
-      avg_duration = total_duration / length(recent_metrics)
+  # Require at least three samples before doing anything — match directly on the
+  # list prefix instead of calling length/1 so we short-circuit for short lists.
+  defp optimize_based_on_performance(%{performance_history: [_, _, _ | _] = history} = state) do
+    recent_metrics = Enum.take(history, 5)
+    sample_size = length(recent_metrics)
+    avg_throughput = average(recent_metrics, & &1.throughput, sample_size)
+    avg_duration = average(recent_metrics, & &1.duration_ms, sample_size)
 
-      # Adjust batch size based on performance
-      new_batch_size = calculate_optimal_batch_size(avg_throughput, avg_duration, state.current_batch_size)
+    new_batch_size = calculate_optimal_batch_size(avg_throughput, avg_duration, state.current_batch_size)
+    new_insert_options = calculate_insert_options(avg_duration)
 
-      # Adjust INSERT options based on system load
-      new_insert_options = calculate_insert_options(avg_duration)
+    Logger.debug(
+      "INSERT optimization: batch_size=#{new_batch_size}, avg_throughput=#{Float.round(avg_throughput, 2)} pps"
+    )
 
-      Logger.debug(
-        "INSERT optimization: batch_size=#{new_batch_size}, avg_throughput=#{Float.round(avg_throughput, 2)} pps"
-      )
+    :telemetry.execute([:aprsme, :insert_optimizer, :batch_size], %{value: new_batch_size}, %{})
+    :telemetry.execute([:aprsme, :insert_optimizer, :throughput], %{value: avg_throughput}, %{})
+    :telemetry.execute([:aprsme, :insert_optimizer, :duration], %{value: avg_duration}, %{})
+    maybe_emit_optimization(new_batch_size, state.current_batch_size)
 
-      # Emit telemetry for monitoring
-      :telemetry.execute([:aprsme, :insert_optimizer, :batch_size], %{value: new_batch_size}, %{})
-      :telemetry.execute([:aprsme, :insert_optimizer, :throughput], %{value: avg_throughput}, %{})
-      :telemetry.execute([:aprsme, :insert_optimizer, :duration], %{value: avg_duration}, %{})
-
-      if new_batch_size != state.current_batch_size do
-        :telemetry.execute([:aprsme, :insert_optimizer, :optimizations], %{count: 1}, %{})
-      end
-
-      %{
-        state
-        | current_batch_size: new_batch_size,
-          insert_options: new_insert_options,
-          last_optimization: System.monotonic_time(:millisecond)
-      }
-    else
+    %{
       state
-    end
+      | current_batch_size: new_batch_size,
+        insert_options: new_insert_options,
+        last_optimization: System.monotonic_time(:millisecond)
+    }
+  end
+
+  defp optimize_based_on_performance(state), do: state
+
+  defp average(items, getter, count) do
+    items |> Enum.map(getter) |> Enum.sum() |> Kernel./(count)
+  end
+
+  defp maybe_emit_optimization(same, same), do: :ok
+
+  defp maybe_emit_optimization(_new, _old) do
+    :telemetry.execute([:aprsme, :insert_optimizer, :optimizations], %{count: 1}, %{})
   end
 
   defp calculate_optimal_batch_size(avg_throughput, avg_duration, current_batch_size) do
@@ -158,21 +161,17 @@ defmodule Aprsme.Performance.InsertOptimizer do
     end
   end
 
-  defp calculate_insert_options(avg_duration) do
-    base_options = default_insert_options()
-
-    # If INSERTs are taking too long, use more aggressive optimizations
-    if avg_duration > 3000 do
-      Keyword.merge(base_options,
-        returning: false,
-        on_conflict: :nothing,
-        timeout: 30_000
-      )
-    else
-      base_options
-    end
+  # When INSERTs are slow (>3s avg), use a longer timeout; otherwise stick with defaults.
+  defp calculate_insert_options(avg_duration) when avg_duration > 3_000 do
+    Keyword.merge(default_insert_options(),
+      returning: false,
+      on_conflict: :nothing,
+      timeout: 30_000
+    )
   end
 
+  defp calculate_insert_options(_avg_duration), do: default_insert_options()
+
   defp default_insert_options do
     [
       # Don't return IDs unless needed

lib/aprsme_web/live/map_live/navigation.ex

@@ -21,25 +21,32 @@ defmodule AprsmeWeb.MapLive.Navigation do
   def determine_map_location(params, session) do
     {url_center, url_zoom} = UrlParams.parse_map_params(params)
     has_explicit_url_params = UrlParams.has_explicit_url_params?(params)
+    geo = session["ip_geolocation"]
 
     Logger.info(
-      "determine_map_location: session ip_geolocation=#{inspect(session["ip_geolocation"])}, has_explicit_url_params=#{has_explicit_url_params}"
+      "determine_map_location: session ip_geolocation=#{inspect(geo)}, has_explicit_url_params=#{has_explicit_url_params}"
     )
 
-    case session["ip_geolocation"] do
-      %{"lat" => lat, "lng" => lng} when is_number(lat) and is_number(lng) ->
-        if has_explicit_url_params do
-          Logger.info("Using URL params over geolocation: center=#{inspect(url_center)}, zoom=#{url_zoom}")
-          {url_center, url_zoom, false}
-        else
-          Logger.info("Using IP geolocation: lat=#{lat}, lng=#{lng}, zoom=11")
-          {%{lat: lat, lng: lng}, 11, true}
-        end
+    resolve_location(geo, has_explicit_url_params, url_center, url_zoom)
+  end
 
-      _ ->
-        Logger.info("No IP geolocation in session, using defaults")
-        {url_center, url_zoom, !has_explicit_url_params}
-    end
+  # Explicit URL params always win over geolocation.
+  defp resolve_location(_geo, true, url_center, url_zoom) do
+    Logger.info("Using URL params over geolocation: center=#{inspect(url_center)}, zoom=#{url_zoom}")
+    {url_center, url_zoom, false}
+  end
+
+  # Valid geolocation + no explicit URL params → use the geolocation.
+  defp resolve_location(%{"lat" => lat, "lng" => lng}, false, _url_center, _url_zoom)
+       when is_number(lat) and is_number(lng) do
+    Logger.info("Using IP geolocation: lat=#{lat}, lng=#{lng}, zoom=11")
+    {%{lat: lat, lng: lng}, 11, true}
+  end
+
+  # No usable geolocation → fall back to URL/defaults.
+  defp resolve_location(_geo, has_explicit_url_params, url_center, url_zoom) do
+    Logger.info("No IP geolocation in session, using defaults")
+    {url_center, url_zoom, !has_explicit_url_params}
   end
 
   @doc """
@@ -47,27 +54,20 @@ defmodule AprsmeWeb.MapLive.Navigation do
   Returns {final_map_center, final_map_zoom}.
   """
   @spec handle_callsign_tracking(binary(), map(), integer(), boolean()) :: {map(), integer()}
-  def handle_callsign_tracking(tracked_callsign, map_center, map_zoom, has_explicit_url_params) do
-    if tracked_callsign != "" and not has_explicit_url_params do
-      try do
-        case Packets.get_latest_packet_for_callsign(tracked_callsign) do
-          %{lat: lat, lon: lon} when is_number(lat) and is_number(lon) ->
-            {%{lat: lat, lng: lon}, 12}
+  def handle_callsign_tracking("", map_center, map_zoom, _), do: {map_center, map_zoom}
+  def handle_callsign_tracking(_, map_center, map_zoom, true), do: {map_center, map_zoom}
 
-          _ ->
-            {map_center, map_zoom}
-        end
-      rescue
-        # Handle database connection errors gracefully (especially in tests)
-        DBConnection.OwnershipError ->
-          {map_center, map_zoom}
+  def handle_callsign_tracking(tracked_callsign, map_center, map_zoom, false) do
+    case Packets.get_latest_packet_for_callsign(tracked_callsign) do
+      %{lat: lat, lon: lon} when is_number(lat) and is_number(lon) ->
+        {%{lat: lat, lng: lon}, 12}
 
-        _ ->
-          {map_center, map_zoom}
-      end
-    else
-      {map_center, map_zoom}
+      _ ->
+        {map_center, map_zoom}
     end
+  rescue
+    # Handle database connection errors gracefully (especially in tests).
+    _error -> {map_center, map_zoom}
   end
 
   @doc """
@@ -77,12 +77,15 @@ defmodule AprsmeWeb.MapLive.Navigation do
   def handle_callsign_search("", socket), do: {:noreply, socket}
 
   def handle_callsign_search(callsign, socket) do
-    if ParamUtils.valid_callsign?(callsign) do
-      # Navigate to the new URL structure with the callsign as a path param
-      {:noreply, LiveView.push_navigate(socket, to: "/#{callsign}")}
-    else
-      {:noreply, LiveView.put_flash(socket, :error, "Invalid callsign format")}
-    end
+    dispatch_callsign_search(ParamUtils.valid_callsign?(callsign), callsign, socket)
+  end
+
+  defp dispatch_callsign_search(true, callsign, socket) do
+    {:noreply, LiveView.push_navigate(socket, to: "/#{callsign}")}
+  end
+
+  defp dispatch_callsign_search(false, _callsign, socket) do
+    {:noreply, LiveView.put_flash(socket, :error, "Invalid callsign format")}
   end
 
   @doc """

test/aprsme/performance/insert_optimizer_test.exs

@@ -0,0 +1,153 @@
+defmodule Aprsme.Performance.InsertOptimizerTest do
+  use ExUnit.Case, async: true
+
+  alias Aprsme.Performance.InsertOptimizer
+
+  defp fresh_state do
+    %{
+      current_batch_size: 200,
+      insert_options: [returning: false, on_conflict: :nothing, timeout: 15_000],
+      performance_history: [],
+      last_optimization: System.monotonic_time(:millisecond)
+    }
+  end
+
+  defp metric(throughput, duration_ms) do
+    %{
+      batch_size: 200,
+      duration_ms: duration_ms,
+      success_count: 100,
+      throughput: throughput,
+      timestamp: System.monotonic_time(:millisecond)
+    }
+  end
+
+  describe "GenServer callbacks" do
+    test "handle_call :get_batch_size returns current batch size" do
+      state = fresh_state()
+
+      assert {:reply, 200, ^state} =
+               InsertOptimizer.handle_call(:get_batch_size, self(), state)
+    end
+
+    test "handle_call :get_insert_options returns insert_options" do
+      state = fresh_state()
+      opts = state.insert_options
+      assert {:reply, ^opts, ^state} = InsertOptimizer.handle_call(:get_insert_options, self(), state)
+    end
+
+    test "handle_cast records a new metric in performance_history" do
+      state = fresh_state()
+
+      {:noreply, new_state} =
+        InsertOptimizer.handle_cast({:record_metrics, 200, 1_000, 100}, state)
+
+      assert [entry | _] = new_state.performance_history
+      assert entry.batch_size == 200
+      assert entry.duration_ms == 1_000
+      assert entry.success_count == 100
+      # Throughput = 100 / (1000/1000) = 100 pps
+      assert entry.throughput == 100.0
+    end
+
+    test "handle_cast with zero duration avoids div-by-0, throughput is 0" do
+      state = fresh_state()
+
+      {:noreply, new_state} =
+        InsertOptimizer.handle_cast({:record_metrics, 100, 0, 50}, state)
+
+      assert [entry | _] = new_state.performance_history
+      assert entry.throughput == 0
+    end
+
+    test "performance history is capped at 20 entries" do
+      state = fresh_state()
+
+      final =
+        Enum.reduce(1..25, state, fn _, s ->
+          {:noreply, s2} = InsertOptimizer.handle_cast({:record_metrics, 200, 1000, 100}, s)
+          s2
+        end)
+
+      assert length(final.performance_history) == 20
+    end
+  end
+
+  describe "handle_info :optimize_settings" do
+    test "with fewer than 3 metrics, state is unchanged except for re-scheduled timer" do
+      state = %{fresh_state() | performance_history: [metric(100, 1000), metric(90, 1100)]}
+      {:noreply, new_state} = InsertOptimizer.handle_info(:optimize_settings, state)
+      # Batch size shouldn't have moved.
+      assert new_state.current_batch_size == state.current_batch_size
+      assert new_state.performance_history == state.performance_history
+    end
+
+    test "grows batch size when throughput is high and duration low" do
+      # With avg_throughput > 200 and avg_duration < 2000, batch size should scale up
+      # from 200 → min(@max, round(200 * 1.2)) = 240.
+      history =
+        Enum.map(1..5, fn _ -> metric(300, 1000) end)
+
+      state = %{fresh_state() | performance_history: history}
+      {:noreply, new_state} = InsertOptimizer.handle_info(:optimize_settings, state)
+      assert new_state.current_batch_size == 240
+      # Fast INSERTs keep default options.
+      assert Keyword.get(new_state.insert_options, :timeout) == 15_000
+    end
+
+    test "shrinks batch size when throughput is low and duration high" do
+      # avg_throughput < 50 and avg_duration > 5000 → batch_size drops by 20%.
+      history = Enum.map(1..5, fn _ -> metric(10, 6000) end)
+      state = %{fresh_state() | performance_history: history}
+      {:noreply, new_state} = InsertOptimizer.handle_info(:optimize_settings, state)
+      assert new_state.current_batch_size == 160
+      # Slow INSERTs bump timeout.
+      assert Keyword.get(new_state.insert_options, :timeout) == 30_000
+    end
+
+    test "keeps batch size when performance is middling" do
+      # 100 pps at 3000ms falls in neither bucket → no change to batch size.
+      history = Enum.map(1..5, fn _ -> metric(100, 3000) end)
+      state = %{fresh_state() | performance_history: history}
+      {:noreply, new_state} = InsertOptimizer.handle_info(:optimize_settings, state)
+      assert new_state.current_batch_size == 200
+    end
+
+    test "never drops below the minimum batch size" do
+      state = %{
+        fresh_state()
+        | current_batch_size: 110,
+          performance_history: Enum.map(1..5, fn _ -> metric(5, 10_000) end)
+      }
+
+      {:noreply, new_state} = InsertOptimizer.handle_info(:optimize_settings, state)
+      assert new_state.current_batch_size == 100
+    end
+
+    test "never exceeds the maximum batch size" do
+      state = %{
+        fresh_state()
+        | current_batch_size: 750,
+          performance_history: Enum.map(1..5, fn _ -> metric(500, 500) end)
+      }
+
+      {:noreply, new_state} = InsertOptimizer.handle_info(:optimize_settings, state)
+      assert new_state.current_batch_size == 800
+    end
+  end
+
+  describe "client API when GenServer isn't running" do
+    test "get_optimal_batch_size falls back to base size on :noproc" do
+      # The supervised instance isn't started in the app tree, so this should
+      # hit the catch clause and return the base batch size (200).
+      assert InsertOptimizer.get_optimal_batch_size() == 200
+    end
+
+    test "get_insert_options falls back to default options on :noproc" do
+      opts = InsertOptimizer.get_insert_options()
+      assert Keyword.get(opts, :returning) == false
+      assert Keyword.get(opts, :on_conflict) == :nothing
+      assert Keyword.get(opts, :timeout) == 15_000
+    end
+  end
+end

test/aprsme/signal_handler_test.exs

@@ -0,0 +1,16 @@
+defmodule Aprsme.SignalHandlerTest do
+  use ExUnit.Case, async: true
+
+  alias Aprsme.SignalHandler
+
+  describe "handle_info/2" do
+    test "ignores unrecognized messages without changing state" do
+      state = %{some: :state}
+      assert SignalHandler.handle_info(:random, state) == {:noreply, state}
+      assert SignalHandler.handle_info({:other, "msg"}, state) == {:noreply, state}
+    end
+
+    # We can't safely exercise the :sigterm clause here — it calls
+    # Aprsme.ShutdownHandler.shutdown() which would actually shut the app down.
+  end
+end

test/aprsme_web/live/locale_hook_test.exs

@@ -0,0 +1,87 @@
+defmodule AprsmeWeb.LocaleHookTest do
+  # on_mount/4 mutates the process-wide Gettext locale and reads app env;
+  # serialize with anything else that does the same.
+  use ExUnit.Case, async: false
+
+  alias AprsmeWeb.LocaleHook
+  alias Phoenix.LiveView.Socket
+
+  setup do
+    original_env = Application.get_env(:aprsme, :env)
+    original_locale = Gettext.get_locale(AprsmeWeb.Gettext)
+
+    on_exit(fn ->
+      Application.put_env(:aprsme, :env, original_env)
+      Gettext.put_locale(AprsmeWeb.Gettext, original_locale)
+    end)
+
+    :ok
+  end
+
+  defp bare_socket do
+    %Socket{
+      assigns: %{__changed__: %{}},
+      private: %{}
+    }
+  end
+
+  describe "on_mount/4 in production" do
+    setup do
+      Application.put_env(:aprsme, :env, :prod)
+      :ok
+    end
+
+    test "sets a supported locale from session" do
+      {:cont, socket} = LocaleHook.on_mount(:set_locale, %{}, %{"locale" => "es"}, bare_socket())
+      assert socket.assigns.locale == "es"
+      assert Gettext.get_locale(AprsmeWeb.Gettext) == "es"
+    end
+
+    test "falls back to 'en' for unsupported session locale" do
+      {:cont, socket} = LocaleHook.on_mount(:set_locale, %{}, %{"locale" => "zz"}, bare_socket())
+      assert socket.assigns.locale == "en"
+    end
+
+    test "falls back to 'en' when session has no locale" do
+      {:cont, socket} = LocaleHook.on_mount(:set_locale, %{}, %{}, bare_socket())
+      assert socket.assigns.locale == "en"
+    end
+
+    test "accepts all declared supported locales" do
+      for loc <- ["en", "es", "de", "fr"] do
+        {:cont, socket} =
+          LocaleHook.on_mount(:set_locale, %{}, %{"locale" => loc}, bare_socket())
+
+        assert socket.assigns.locale == loc
+      end
+    end
+  end
+
+  describe "on_mount/4 in non-prod" do
+    test "leaves locale assign as nil" do
+      Application.put_env(:aprsme, :env, :dev)
+      {:cont, socket} = LocaleHook.on_mount(:set_locale, %{}, %{"locale" => "es"}, bare_socket())
+      assert socket.assigns.locale == nil
+    end
+  end
+
+  describe "on_mount/4 map_page assign" do
+    test "map_page is false for non-MapLive socket" do
+      Application.put_env(:aprsme, :env, :dev)
+      {:cont, socket} = LocaleHook.on_mount(:set_locale, %{}, %{}, bare_socket())
+      assert socket.assigns.map_page == false
+    end
+
+    test "map_page is true when the socket's view is MapLive.Index" do
+      Application.put_env(:aprsme, :env, :dev)
+
+      socket = %Socket{
+        assigns: %{__changed__: %{}},
+        private: %{phoenix_live_view: %{view: AprsmeWeb.MapLive.Index}}
+      }
+
+      {:cont, socket} = LocaleHook.on_mount(:set_locale, %{}, %{}, socket)
+      assert socket.assigns.map_page == true
+    end
+  end
+end

test/aprsme_web/live/map_live/navigation_test.exs

@@ -0,0 +1,112 @@
+defmodule AprsmeWeb.MapLive.NavigationTest do
+  # Logger.info calls are fine during tests; we don't silence them.
+  use ExUnit.Case, async: true
+
+  alias AprsmeWeb.MapLive.Navigation
+  alias Phoenix.LiveView.Socket
+
+  describe "determine_map_location/2" do
+    test "explicit URL params win over IP geolocation" do
+      params = %{"lat" => "40.0", "lng" => "-95.0", "z" => "7"}
+      session = %{"ip_geolocation" => %{"lat" => 10.0, "lng" => 20.0}}
+
+      assert {%{lat: 40.0, lng: -95.0}, 7, false} =
+               Navigation.determine_map_location(params, session)
+    end
+
+    test "valid IP geolocation used when no explicit URL params" do
+      session = %{"ip_geolocation" => %{"lat" => 45.5, "lng" => -122.6}}
+      assert {%{lat: 45.5, lng: -122.6}, 11, true} = Navigation.determine_map_location(%{}, session)
+    end
+
+    test "missing or invalid geolocation falls back to URL defaults" do
+      # No geolocation and no URL params → default center + skip_initial_url_update=true
+      assert {%{lat: _, lng: _}, _zoom, true} = Navigation.determine_map_location(%{}, %{})
+
+      # Geolocation present but with non-numeric values → fall back
+      session = %{"ip_geolocation" => %{"lat" => "not-a-number", "lng" => "nope"}}
+      assert {%{lat: _, lng: _}, _zoom, true} = Navigation.determine_map_location(%{}, session)
+    end
+
+    test "URL params win even with malformed geolocation" do
+      session = %{"ip_geolocation" => %{"lat" => "oops", "lng" => "oops"}}
+      params = %{"lat" => "10.0"}
+      {_, _, skip?} = Navigation.determine_map_location(params, session)
+      assert skip? == false
+    end
+  end
+
+  describe "handle_callsign_tracking/4" do
+    @default_center %{lat: 10.0, lng: 20.0}
+    @default_zoom 5
+
+    test "empty callsign returns unchanged center and zoom" do
+      assert Navigation.handle_callsign_tracking("", @default_center, @default_zoom, false) ==
+               {@default_center, @default_zoom}
+
+      assert Navigation.handle_callsign_tracking("", @default_center, @default_zoom, true) ==
+               {@default_center, @default_zoom}
+    end
+
+    test "when explicit URL params are set, tracking is bypassed" do
+      assert Navigation.handle_callsign_tracking("K5ABC", @default_center, @default_zoom, true) ==
+               {@default_center, @default_zoom}
+    end
+
+    test "returns defaults when the database lookup raises" do
+      # With a callsign that won't match any test data and no DB ownership,
+      # the rescue clause returns the defaults.
+      assert Navigation.handle_callsign_tracking(
+               "NONEXISTENT-99",
+               @default_center,
+               @default_zoom,
+               false
+             ) == {@default_center, @default_zoom}
+    end
+  end
+
+  describe "handle_callsign_search/2" do
+    test "empty string returns the socket untouched" do
+      socket = %Socket{assigns: %{__changed__: %{}}}
+      assert {:noreply, ^socket} = Navigation.handle_callsign_search("", socket)
+    end
+
+    test "invalid callsign puts a flash error" do
+      socket = %Socket{assigns: %{__changed__: %{}, flash: %{}}}
+      {:noreply, result} = Navigation.handle_callsign_search("HELLO WORLD", socket)
+      assert result.assigns.flash["error"] == "Invalid callsign format"
+    end
+
+    test "valid callsign triggers push_navigate" do
+      socket = %Socket{
+        assigns: %{__changed__: %{}, flash: %{}},
+        redirected: nil
+      }
+
+      {:noreply, result} = Navigation.handle_callsign_search("K5ABC-9", socket)
+      # push_navigate/2 sets the `redirected` field on the socket.
+      assert result.redirected
+    end
+  end
+
+  describe "update_and_zoom_to_location/4" do
+    test "sets map_center and map_zoom assigns, and pushes a zoom event" do
+      socket = %Socket{assigns: %{__changed__: %{}}}
+      result = Navigation.update_and_zoom_to_location(socket, 30.5, -95.0, 8)
+      assert result.assigns.map_center == %{lat: 30.5, lng: -95.0}
+      assert result.assigns.map_zoom == 8
+    end
+  end
+
+  describe "zoom_to_current_location/1" do
+    test "pushes a zoom_to_location event using the socket's center/zoom" do
+      socket = %Socket{
+        assigns: %{__changed__: %{}, map_center: %{lat: 1.0, lng: 2.0}, map_zoom: 10}
+      }
+
+      # The function returns the socket (with push_event recorded).
+      result = Navigation.zoom_to_current_location(socket)
+      assert %Socket{} = result
+    end
+  end
+end