roachprod: refactor ssh.go

Third part of #47567 where we need to refactor ssh.go (as one type structure is in use, we cannot remove it completely).

So we are refactoring ssh.go and change its name to io.go and only keeping ProgressWriter struct and function

Also we are adding a unit test go code to ensure it works as expected.

Release note: None

pkg/cmd/roachprod/ssh/BUILD.bazel

@@ -1,11 +1,17 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "ssh",
     srcs = [
+        "io.go",
         "shell.go",
-        "ssh.go",
     ],
     importpath = "github.com/cockroachdb/cockroach/pkg/cmd/roachprod/ssh",
     visibility = ["//visibility:public"],
 )
+
+go_test(
+    name = "ssh_test",
+    srcs = ["io_test.go"],
+    embed = [":ssh"],
+)

pkg/cmd/roachprod/ssh/io_test.go

@@ -0,0 +1,49 @@
+// Copyright 2018 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package ssh
+
+import (
+	"io/ioutil"
+	"testing"
+)
+
+func TestProgress(t *testing.T) {
+	output, err := ioutil.TempFile("", "example*")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer output.Close()
+
+	b := make([]byte, 10)
+	var percent float64
+	writer := &ProgressWriter{
+		Writer: output,
+		Done:   0,
+		Total:  50,
+		Progress: func(currentProgress float64) {
+			percent = currentProgress
+		},
+	}
+	for i := 0; i < 4; i++ {
+		if _, err := writer.Write(b); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if percent != 0.8 {
+		t.Errorf("expected progress of 80%% but got %.2f", percent*100)
+	}
+	if _, err := writer.Write(b); err != nil {
+		t.Fatal(err)
+	}
+	if percent != 1.0 {
+		t.Errorf("expected progress of 100%% but got %.2f", percent*100)
+	}
+}