Use special init file in tests

The main purpose at the moment is to select a compatible colorscheme for
neovim v0.9 ad v0.10.

test/fixtures/init.lua

@@ -0,0 +1,5 @@
+-- This is a nvimpager init file for the test suite.
+
+if vim.fn.has("nvim-0.10") == 1 then
+  vim.cmd.colorscheme("vim")
+end

test/nvimpager_spec.lua

@@ -74,16 +74,16 @@ describe("cat mode", function()
     end)
   end)
 
-  it("displays a small file with syntax highlighting to stdout", function()
-    local output = run("./nvimpager -c test/fixtures/makefile")
+  it("displays a small file with syntax highlighting to stdout #colorscheme", function()
+    local output = run("./nvimpager -c test/fixtures/makefile -u test/fixtures/init.lua")
     local expected = read("test/fixtures/makefile.ansi")
     assert.equal(expected, output)
   end)
 
-  it("reads stdin with syntax highlighting", function()
+  it("reads stdin with syntax highlighting #colorscheme", function()
     local output = run("./nvimpager -c -- " ..
-		       "-c 'set filetype=make' " ..
-                       "< test/fixtures/makefile")
+		       "-c 'set filetype=make'  -u test/fixtures/init.lua " ..
+                       " < test/fixtures/makefile")
     local expected = read("test/fixtures/makefile.ansi")
     assert.equal(expected, output)
   end)
@@ -94,24 +94,24 @@ describe("cat mode", function()
     assert.equal(expected, output)
   end)
 
-  it("handles color schemes with a non trivial Normal group", function()
+  it("handles color schemes with a non trivial Normal group #colorscheme", function()
     local output = run("./nvimpager -c test/fixtures/conceal.tex " ..
-		       "--cmd 'hi Normal ctermfg=Red'")
+		       " -u test/fixtures/init.lua --cmd 'hi Normal ctermfg=Red'")
     local expected = read("test/fixtures/conceal.tex.red")
     assert.equal(expected, output)
   end)
 
-  it("highlights all files", function()
+  it("highlights all files #colorscheme", function()
     local output = run("./nvimpager -c test/fixtures/makefile " ..
-                                      "test/fixtures/help.txt ")
+				      "test/fixtures/help.txt -u test/fixtures/init.lua")
     local expected = read("test/fixtures/makefile.ansi") ..
                      read("test/fixtures/help.txt.ansi")
     assert.equal(expected, output)
   end)
 
-  it("concatenates the same file twice", function()
+  it("concatenates the same file twice #colorscheme", function()
     local output = run("./nvimpager -c test/fixtures/makefile " ..
-                                      "test/fixtures/makefile ")
+                                      "test/fixtures/makefile -u test/fixtures/init.lua")
     local expected = read("test/fixtures/makefile.ansi")
     expected = expected .. expected
     assert.equal(expected, output)
@@ -130,22 +130,22 @@ describe("cat mode", function()
     assert.equal('', output)
   end)
 
-  it("explicit - as file argument means stdin", function()
-    local shell_command = "echo foo | ./nvimpager -c - test/fixtures/makefile"
+  it("explicit - as file argument means stdin #colorscheme", function()
+    local shell_command = "echo foo | ./nvimpager -c - test/fixtures/makefile  -u test/fixtures/init.lua"
     local output = run("sh -c '" .. shell_command .. "'")
     local expected = "\27[0mfoo\27[0m\n" ..
 		     read("test/fixtures/makefile.ansi")
     assert.equal(expected, output)
   end)
 
-  it("prefers file arguments over stdin", function()
-    local shell_command = "echo foo | ./nvimpager -c test/fixtures/makefile"
+  it("prefers file arguments over stdin #colorscheme", function()
+    local shell_command = "echo foo | ./nvimpager -c test/fixtures/makefile -u test/fixtures/init.lua"
     local output = run("sh -c '" .. shell_command .. "'")
     assert.equal(read("test/fixtures/makefile.ansi"), output)
   end)
 
-  it("can show stdin as the second file",  function()
-    local output = run("echo foo | ./nvimpager -c test/fixtures/makefile -")
+  it("can show stdin as the second file #colorscheme",  function()
+    local output = run("echo foo | ./nvimpager -c test/fixtures/makefile - -u test/fixtures/init.lua")
     local expected = read("test/fixtures/makefile.ansi") .. "\27[0mfoo\27[0m\n"
     assert.equal(expected, output)
   end)