new 'file_encoding' assert method + test

lib/cmdtest/testcase.rb

@@ -487,6 +487,30 @@ module Cmdtest
       :other_error
     end
 
+    # Assert file encoding
+    def file_encoding(file, enc, bom: nil)
+      _process_after do
+        bytes = nil
+        File.open(file, 'rb') do |f|
+          bytes = f.read
+        end
+        str = bytes.force_encoding(enc)
+        valid = str.valid_encoding?
+        _assert valid do
+          "file not in encoding: #{file}, #{enc}"
+        end
+        if valid && bom != nil
+          has_bom = str.size >= 1 && str.codepoints[0] == 0xfeff
+          _assert ! (! bom && has_bom) do
+            "file has unexpected BOM: #{file}"
+          end
+          _assert ! (bom && ! has_bom) do
+            "file hasn't expected BOM: #{file}"
+          end
+        end
+      end
+    end
+
     # Assert file equal to specific value.
     def file_equal(file, expected)
       _file_equal_aux(true, file, expected)

t/CMDTEST_file_encoding.rb

@@ -0,0 +1,114 @@
+
+require "selftest_utils"
+
+class CMDTEST_file_encoding < Cmdtest::Testcase
+
+  include SelftestUtils
+
+  #----------------------------------------
+  # 'file_encoding' detects equal file encoding + bom
+
+  def test_file_encoding_UTF8_CORRECT
+    create_CMDTEST_foo [
+      "file_open('foo', 'w') {|f| f.write \"\\uFEFFabc-αβγ-Г-א-åäö\\n\" }",
+      "",
+      "cmd 'true.rb' do",
+      "    file_encoding 'foo', 'UTF-8'",
+      "end",
+    ]
+
+    cmd_cmdtest do
+      stdout_equal [
+        "### true.rb",
+      ]
+    end
+  end
+
+  def test_file_encoding_UTF8_INCORRECT
+    create_CMDTEST_foo [
+      "file_open('foo', 'wb') {|f| f.write \"\\xffabc-αβγ-Г-א-åäö\\n\" }",
+      "",
+      "cmd 'true.rb' do",
+      "    file_encoding 'foo', 'UTF-8'",
+      "end",
+    ]
+
+    cmd_cmdtest do
+      stdout_equal [
+        "### true.rb",
+        "--- ERROR: file not in encoding: foo, UTF-8",
+      ]
+      exit_nonzero
+    end
+  end
+
+  def test_file_encoding_UTF8_CORRECT_BOM_true_CORRECT
+    create_CMDTEST_foo [
+      "file_open('foo', 'w') {|f| f.write \"\\uFEFFabc-αβγ-Г-א-åäö\\n\" }",
+      "",
+      "cmd 'true.rb' do",
+      "    file_encoding 'foo', 'UTF-8', bom: true",
+      "end",
+    ]
+
+    cmd_cmdtest do
+      stdout_equal [
+        "### true.rb",
+      ]
+    end
+  end
+
+  def test_file_encoding_UTF8_CORRECT_BOM_false_INCORRECT
+    create_CMDTEST_foo [
+      "file_open('foo', 'w') {|f| f.write \"\\uFEFFabc-αβγ-Г-א-åäö\\n\" }",
+      "",
+      "cmd 'true.rb' do",
+      "    file_encoding 'foo', 'UTF-8', bom: false",
+      "end",
+    ]
+
+    cmd_cmdtest do
+      stdout_equal [
+        "### true.rb",
+        "--- ERROR: file has unexpected BOM: foo",
+      ]
+      exit_nonzero
+    end
+  end
+
+  def test_file_encoding_UTF8_CORRECT_BOM_false_CORRECT
+    create_CMDTEST_foo [
+      "file_open('foo', 'w') {|f| f.write \"abc-αβγ-Г-א-åäö\\n\" }",
+      "",
+      "cmd 'true.rb' do",
+      "    file_encoding 'foo', 'UTF-8', bom: false",
+      "end",
+    ]
+
+    cmd_cmdtest do
+      stdout_equal [
+        "### true.rb",
+      ]
+    end
+  end
+
+  def test_file_encoding_UTF8_CORRECT_BOM_true_INCORRECT
+    create_CMDTEST_foo [
+      "file_open('foo', 'w') {|f| f.write \"abc-αβγ-Г-א-åäö\\n\" }",
+      "",
+      "cmd 'true.rb' do",
+      "    file_encoding 'foo', 'UTF-8', bom: true",
+      "end",
+    ]
+
+    cmd_cmdtest do
+      stdout_equal [
+        "### true.rb",
+        "--- ERROR: file hasn't expected BOM: foo",
+      ]
+      exit_nonzero
+    end
+  end
+
+
+end