io: introduce a go-like io.util module (#6323)

vlib/io/util/util_test.v

@@ -0,0 +1,127 @@
+import os
+import io.util
+
+const (
+	// tfolder will contain all the temporary files/subfolders made by
+	// the different tests. It would be removed in testsuite_end(), so
+	// individual os tests do not need to clean up after themselves.
+	tfolder = os.join_path(os.temp_dir(), 'v', 'tests', 'io_util_test')
+)
+
+fn testsuite_begin() {
+	eprintln('testsuite_begin, tfolder = $tfolder')
+	os.rmdir_all(tfolder)
+	assert !os.is_dir(tfolder)
+	os.mkdir_all(tfolder)
+	os.chdir(tfolder)
+	assert os.is_dir(tfolder)
+}
+
+fn testsuite_end() {
+	os.chdir(os.wd_at_startup)
+	os.rmdir_all(tfolder)
+	assert !os.is_dir(tfolder)
+	// eprintln('testsuite_end  , tfolder = $tfolder removed.')
+}
+
+fn test_temp_file() {
+	// Test defaults
+	mut f, mut path := util.temp_file({}) or {
+		assert false
+		return
+	}
+	mut prev_path := path
+	defer {
+		f.close()
+	}
+	assert os.is_file(path)
+	assert f.is_opened
+	// Test pattern
+	f.close()
+	f, path = util.temp_file({
+		pattern: 'some_*_test.file'
+	}) or {
+		assert false
+		return
+	}
+	assert path != prev_path
+	assert os.is_file(path)
+	assert f.is_opened
+	mut filename := os.file_name(path)
+	assert filename.contains('_test.file')
+	// Check for 9 digits where the wildcard is placed in the pattern
+	for i, c in filename {
+		if i > 4 && i <= 4 + 9 {
+			assert c.is_digit()
+		}
+	}
+	// Test custom path
+	prev_path = path
+	f.close()
+	f, path = util.temp_file({
+		path: tfolder
+	}) or {
+		assert false
+		return
+	}
+	assert path != prev_path
+	assert os.is_file(path)
+	assert path.contains(tfolder)
+	assert f.is_opened
+	filename = os.file_name(path)
+	for c in filename {
+		assert c.is_digit()
+	}
+}
+
+fn test_temp_dir() {
+	// Test defaults
+	mut path := util.temp_dir({}) or {
+		assert false
+		return
+	}
+	assert os.is_dir(path)
+	mut writable := os.is_writable_folder(path) or {
+		assert false
+		return
+	}
+	assert writable
+	mut prev_path := path
+	// Test pattern
+	path = util.temp_dir({
+		pattern: 'some_*_test_dir'
+	}) or {
+		assert false
+		return
+	}
+	assert path != prev_path
+	assert os.is_dir(path)
+	mut filename := os.file_name(path)
+	assert filename.contains('_test_dir')
+	// Check for 9 digits where the wildcard is placed in the pattern
+	for i, c in filename {
+		if i > 4 && i <= 4 + 9 {
+			assert c.is_digit()
+		}
+	}
+	// Test custom path
+	prev_path = path
+	path = util.temp_dir({
+		path: tfolder
+	}) or {
+		assert false
+		return
+	}
+	assert path != prev_path
+	assert os.is_dir(path)
+	writable = os.is_writable_folder(path) or {
+		assert false
+		return
+	}
+	assert writable
+	assert path.contains(tfolder)
+	filename = os.file_name(path)
+	for c in filename {
+		assert c.is_digit()
+	}
+}