hello-world: add more detailed explanation concerning the test consis…

…tency setup (#532)

Closes #515

exercises/hello-world/hello_test.go

@@ -7,11 +7,20 @@ import "testing"
 // In other words, define a function with the following signature:
 // HelloWorld() string
 //
-// Also define a testVersion with a value that matches
-// the targetTestVersion here.
-
+// In any exercise solution using the following tests you must also define a
+// "testVersion" constant with a value that matches the targetTestVersion
+// here. See how it is done in the the ./hello_world.go file provided.
+// This is a common convention for ensuring test consistency throughout the
+// Exercism Go language track.
+//
+// See TestTestVersion function below for how this and the testVersion
+// constants are used.
 const targetTestVersion = 4
 
+// TestTestVersion is used to ensure the exercise solution is considered
+// compatible with the rest of the tests. It should be the initial testing
+// function in any test suite. If there is an incompatibility the tests can
+// be considered unreliable therefore this function will abort the testing.
 func TestTestVersion(t *testing.T) {
 	if testVersion != targetTestVersion {
 		t.Fatalf("Found testVersion = %v, want %v", testVersion, targetTestVersion)

exercises/hello-world/hello_world.go

@@ -10,6 +10,16 @@ package greeting
 // after you have posted this code to the Exercism site -- reviewers
 // will see that your code can't necessarily be expected to pass the
 // current test suite because it was written to an earlier test version.
+//
+// This is a convention done for Exercism exercises in the Go language track,
+// it is not a requirement of the Go programming language.
+//
+// This test versioning setup will be common to all the exercises in the
+// Go language track. When crafting your own solution file from scratch you
+// will be expected to add this constant or the initial test will fail.
+// The version number you should use will be found in the constant
+// "targetTestVersion" in the test file, see ./hello_test.go for more
+// information.
 const testVersion = 4
 
 // HelloWorld needs a comment documenting it as package does.