fix: restore window options on split windows (#36)

tests/win_options_spec.lua

@@ -0,0 +1,38 @@
+local oil = require("oil")
+local test_util = require("tests.test_util")
+
+describe("window options", function()
+  after_each(function()
+    test_util.reset_editor()
+  end)
+
+  it("Restores window options on close", function()
+    vim.cmd.edit({ args = { "README.md" } })
+    oil.open()
+    assert.equals("no", vim.o.signcolumn)
+    oil.close()
+    assert.equals("auto", vim.o.signcolumn)
+  end)
+
+  it("Restores window options on edit", function()
+    oil.open()
+    assert.equals("no", vim.o.signcolumn)
+    vim.cmd.edit({ args = { "README.md" } })
+    assert.equals("auto", vim.o.signcolumn)
+  end)
+
+  it("Restores window options on split <filename>", function()
+    oil.open()
+    assert.equals("no", vim.o.signcolumn)
+    vim.cmd.split({ args = { "README.md" } })
+    assert.equals("auto", vim.o.signcolumn)
+  end)
+
+  it("Restores window options on split", function()
+    oil.open()
+    assert.equals("no", vim.o.signcolumn)
+    vim.cmd.split()
+    vim.cmd.edit({ args = { "README.md" } })
+    assert.equals("auto", vim.o.signcolumn)
+  end)
+end)