Added Elixir IO and the file system tests

test/elixir_io_and_the_file_system_test.exs

@@ -0,0 +1,75 @@
+defmodule IoAndFileSystemTest do
+  use ExUnit.Case
+  import ExUnit.CaptureIO
+
+  describe "IO module" do
+    test "writes to standard output" do
+      assert capture_io(fn -> IO.puts("hello world") end) == "hello world\n"
+    end
+
+    test "reads from standard input" do
+      assert capture_io("yes\n", fn ->
+               assert IO.gets("yes or no? ") == "yes\n"
+             end)
+    end
+
+    test "writes to standard error" do
+      assert capture_io(:stderr, fn -> IO.puts(:stderr, "error message") end) == "error message\n"
+    end
+  end
+
+  describe "File module" do
+    setup do
+      path = "test_file.txt"
+      on_exit(fn -> File.rm(path) end)
+      {:ok, path: path}
+    end
+
+    test "writes and reads a file in binary mode", %{path: path} do
+      {:ok, file} = File.open(path, [:write])
+      assert IO.binwrite(file, "world") == :ok
+      assert File.close(file) == :ok
+
+      assert File.read(path) == {:ok, "world"}
+    end
+
+    test "reads a file with the bang function", %{path: path} do
+      File.write!(path, "hello")
+      assert File.read!(path) == "hello"
+    end
+
+    test "handles error with File.read" do
+      assert File.read("non_existent_file.txt") == {:error, :enoent}
+    end
+
+    test "raises error with File.read!" do
+      assert_raise File.Error, fn -> File.read!("non_existent_file.txt") end
+    end
+  end
+
+  describe "Path module" do
+    test "joins paths correctly" do
+      assert Path.join("foo", "bar") == "foo/bar"
+    end
+
+    test "expands paths correctly" do
+      assert Path.expand("~/hello") == Path.join(System.user_home!(), "hello")
+    end
+  end
+
+  describe "iodata and chardata" do
+    test "writes iodata" do
+      name = "Mary"
+      assert capture_io(fn -> IO.puts(["Hello ", name, "!"]) end) == "Hello Mary!\n"
+    end
+
+    test "writes chardata with integers" do
+      assert capture_io(fn -> IO.puts([?O, ?l, ?á, ?\s, "Mary", ?!]) end) == "Olá Mary!\n"
+    end
+
+    test "handles nested iodata" do
+      assert capture_io(fn -> IO.puts(["apple", [",", "banana", [",", "lemon"]]]) end) ==
+               "apple,banana,lemon\n"
+    end
+  end
+end