package main

import (
	"bytes"
	"testing"
)

// TestGreetNoArguments tests the greeter's response when given no names.
func TestGreetNoArguments(t *testing.T) {
	buffer := new(bytes.Buffer)
	args := make([]string, 0)

	if err := greet(buffer, args); err != nil {
		t.Fatalf("an error occured while running greet(): %s", err)
	}

	want := "Hello, World!\n"
	got := buffer.String()

	if want != got {
		t.Errorf("unexpected output returned from greet(): want '%s', got '%s'", want, got)
	} else {
		t.Logf("expected output returned from greet(): got '%s'", got)
	}
}

// TestGreetOneArgument tests the greeter's response when given one name.
func TestGreetOneArgument(t *testing.T) {
	buffer := new(bytes.Buffer)
	args := []string{"Sarah"}

	if err := greet(buffer, args); err != nil {
		t.Fatalf("an error occured while running greet(): %s", err)
	}

	want := "Hello, Sarah!\n"
	got := buffer.String()

	if want != got {
		t.Errorf("unexpected output returned from greet(): want '%s', got '%s'", want, got)
	} else {
		t.Logf("expected output returned from greet(): got '%s'", got)
	}
}

// TestGreetTwoArguments tests the greeter's response when given two names.
func TestGreetTwoArguments(t *testing.T) {
	buffer := new(bytes.Buffer)
	args := []string{"Bob", "John"}

	want := "unexpected number of arguments passed to the greeter: want 0 or 1 argument, got 2"
	
	err := greet(buffer, args)

	if err == nil {
		t.Error("unexpected nil error returned.")
	}

	got := err.Error()

	if want != got {
		t.Errorf("unexpected error message returned: want '%s', got '%s'", want, got)
	} else {
		t.Logf("expected error message returned: got '%s'", got)
	}
}