Fix divide-by-zero error in indexed_ratio

Dividing by `max_block_number` assumes it is 1-based, but it is 0-based,
so add 1.

apps/block_scout_web/test/block_scout_web/features/viewing_app_test.exs

@@ -7,50 +7,58 @@ defmodule BlockScoutWeb.ViewingAppTest do
 
   describe "loading bar when indexing" do
     test "shows blocks indexed percentage", %{session: session} do
-      for index <- 6..10 do
+      for index <- 5..9 do
         insert(:block, number: index)
       end
 
+      assert Explorer.Chain.indexed_ratio() == 0.5
+
       session
       |> AppPage.visit_page()
       |> assert_has(AppPage.indexed_status("50% Blocks Indexed"))
     end
 
     test "shows tokens loading", %{session: session} do
-      for index <- 1..10 do
+      for index <- 0..9 do
         insert(:block, number: index)
       end
 
+      assert Explorer.Chain.indexed_ratio() == 1.0
+
       session
       |> AppPage.visit_page()
       |> assert_has(AppPage.indexed_status("Indexing Tokens"))
     end
 
     test "live updates blocks indexed percentage", %{session: session} do
-      for index <- 6..10 do
+      for index <- 5..9 do
         insert(:block, number: index)
       end
 
+      assert Explorer.Chain.indexed_ratio() == 0.5
+
       session
       |> AppPage.visit_page()
       |> assert_has(AppPage.indexed_status("50% Blocks Indexed"))
 
-      insert(:block, number: 5)
+      insert(:block, number: 4)
       Notifier.handle_event({:chain_event, :blocks, :catchup, []})
 
       assert_has(session, AppPage.indexed_status("60% Blocks Indexed"))
     end
 
     test "live updates when blocks are fully indexed", %{session: session} do
-      for index <- 2..10 do
+      for index <- 1..9 do
         insert(:block, number: index)
       end
 
+      assert Explorer.Chain.indexed_ratio() == 0.9
+
       session
       |> AppPage.visit_page()
       |> assert_has(AppPage.indexed_status("90% Blocks Indexed"))
 
-      insert(:block, number: 1)
+      insert(:block, number: 0)
       Notifier.handle_event({:chain_event, :blocks, :catchup, []})
 
       assert_has(session, AppPage.indexed_status("Indexing Tokens"))
@@ -58,10 +66,12 @@ defmodule BlockScoutWeb.ViewingAppTest do
 
     test "live removes message when chain is indexed", %{session: session} do
       [block | _] =
-        for index <- 1..10 do
+        for index <- 0..9 do
           insert(:block, number: index)
         end
 
+      assert Explorer.Chain.indexed_ratio() == 1.0
+
       session
       |> AppPage.visit_page()
       |> assert_has(AppPage.indexed_status("Indexing Tokens"))

apps/explorer/lib/explorer/chain.ex

@@ -842,7 +842,7 @@ defmodule Explorer.Chain do
   @doc """
   The percentage of indexed blocks on the chain.
 
-      iex> for index <- 6..10 do
+      iex> for index <- 5..9 do
       ...>   insert(:block, number: index)
       ...> end
       iex> Explorer.Chain.indexed_ratio()
@@ -859,7 +859,7 @@ defmodule Explorer.Chain do
     with {:ok, min_block_number} <- min_block_number(),
          {:ok, max_block_number} <- max_block_number() do
       indexed_blocks = max_block_number - min_block_number + 1
-      indexed_blocks / max_block_number
+      indexed_blocks / (max_block_number + 1)
     else
       {:error, _} -> 0
     end

apps/explorer/test/explorer/chain_test.exs

@@ -820,7 +820,7 @@ defmodule Explorer.ChainTest do
 
   describe "indexed_ratio/0" do
     test "returns indexed ratio" do
-      for index <- 6..10 do
+      for index <- 5..9 do
         insert(:block, number: index)
       end
 
@@ -832,7 +832,7 @@ defmodule Explorer.ChainTest do
     end
 
     test "returns 1.0 if fully indexed blocks" do
-      for index <- 1..10 do
+      for index <- 0..9 do
         insert(:block, number: index)
       end