Minor prop test improvements

.github/workflows/elixir.yml

@@ -23,7 +23,7 @@ jobs:
             otp: '28'
     steps:
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - name: setup
@@ -32,7 +32,7 @@ jobs:
         elixir-version: ${{ matrix.pair.elixir }}
         otp-version: ${{ matrix.pair.otp }}
     - name: Retrieve Cached Dependencies
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       id: mix-cache
       with:
         path: |
@@ -62,7 +62,7 @@ jobs:
           - elixir: '1.19.5'
             otp: '28'
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - name: Setup elixir
@@ -71,7 +71,7 @@ jobs:
         elixir-version: ${{ matrix.pair.elixir }}
         otp-version: ${{ matrix.pair.otp }}
     - name: Retrieve Cached Dependencies
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       id: mix-cache
       with:
         path: |
@@ -96,15 +96,15 @@ jobs:
           - elixir: '1.19.5'
             otp: '28'
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - uses: erlef/setup-beam@v1
       with:
         elixir-version: ${{ matrix.pair.elixir }}
         otp-version: ${{ matrix.pair.otp }}
     - name: Retrieve Cached Dependencies
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       id: mix-cache
       with:
         path: |

.github/workflows/reuse.yaml

@@ -8,6 +8,6 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: REUSE Compliance Check
         uses: fsfe/reuse-action@v4

test/circular_buffer_test.exs

@@ -6,22 +6,30 @@
 #
 defmodule CircularBufferTest do
   use ExUnit.Case, async: false
-  use PropCheck
+  use PropCheck, default_opts: [:quiet, {:numtests, 10_000}]
   doctest CircularBuffer
 
   alias CircularBuffer, as: CB
 
-  property "new/1 accepts a max size" do
-    forall i <- integer() do
+  property "new/1 returns an empty buffer for positive sizes" do
+    forall size <- pos_integer() do
+      cb = CB.new(size)
+
+      cb.max_size == size and
+        cb.count == 0 and
+        cb.a == [] and
+        cb.b == [] and
+        CB.empty?(cb)
+    end
+  end
+
+  property "new/1 raises for non-positive sizes" do
+    forall n <- non_neg_integer() do
       try do
-        buffer = CB.new(i)
-        buffer.max_size == i
+        CB.new(-n)
+        false
       rescue
-        FunctionClauseError ->
-          i <= 0
-
-        _ ->
-          false
+        FunctionClauseError -> true
       end
     end
   end
@@ -44,20 +52,26 @@ defmodule CircularBufferTest do
     end
   end
 
-  property "member?/1" do
-    items = such_that({a, b} <- {pos_integer(), pos_integer()}, when: a != b)
+  property "member?/2 reflects buffer contents" do
+    forall {size, is} <- size_and_list() do
+      iis = Enum.with_index(is)
+      buffer = Enum.reduce(iis, CB.new(size), fn i, cb -> CB.insert(cb, i) end)
+
+      kept = Enum.take(iis, -size)
+      evicted = Enum.drop(iis, -size)
 
-    forall {a, b} <- items do
-      cb = CB.new(1) |> CB.insert(a)
-      !Enum.member?(cb, b) && Enum.member?(cb, a)
+      Enum.all?(kept, &Enum.member?(buffer, &1)) and
+        Enum.all?(evicted, fn x -> not Enum.member?(buffer, x) end) and
+        not Enum.member?(buffer, :never_inserted)
     end
   end
 
   property "implements Enumerable" do
-    forall is <- list(integer()) do
-      buffer = Enum.reduce(is, CB.new(length(is) + 1), fn i, cb -> CB.insert(cb, i) end)
+    forall {size, is} <- size_and_list() do
+      buffer = Enum.reduce(is, CB.new(size), fn i, cb -> CB.insert(cb, i) end)
 
-      Enum.reduce(buffer, 0, fn acc, i -> acc + i end) == Enum.sum(is)
+      Enum.reduce(buffer, 0, fn elem, acc -> acc + elem end) ==
+        Enum.sum(Enum.take(is, -size))
     end
   end
 
@@ -108,11 +122,7 @@ defmodule CircularBufferTest do
 
       buffer = Enum.reduce(iis, CB.new(size), fn i, cb -> CB.insert(cb, i) end)
 
-      oldest =
-        iis
-        |> Enum.reverse()
-        |> Enum.drop(size - 1)
-        |> Enum.at(0)
+      oldest = iis |> Enum.take(-size) |> List.first()
 
       CB.oldest(buffer) == oldest
     end
@@ -156,17 +166,11 @@ defmodule CircularBufferTest do
 
   def size_and_list do
     let size <- pos_integer() do
-      let is <- ints(size * 2 + 1, []) do
-        {size, is}
+      let n <- range(0, size * 2 + 1) do
+        let is <- vector(n, integer()) do
+          {size, is}
+        end
       end
     end
   end
-
-  defp ints(0, acc), do: acc
-
-  defp ints(size, acc) do
-    let i <- integer() do
-      ints(size - 1, [i | acc])
-    end
-  end
 end