ch7ex9/

README

= Exercise 7.9
// Refs:
:chapter: 7
:exercise: 9
:url-base: https://github.com/fenegroni/TGPL-exercise-solutions
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:action: actions/workflows/ch{chapter}ex{exercise}.yml
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{badge-exercise}

Use the `html/template` package (Section 4.6) to replace `printTracks` with a function
that displays the tracks as an HTML table. Use the solution to the previous exercise to arrange
that each click on a column head makes an HTTP request to sort the table.

== Test

The exercise requires us to implement the
integration of
two
separate pieces of functionality:

. the HTML output in table form with hyperlinks in the headers
. the ordering of the table contents to use the ordering from exercise 7.8

The integration of those
two
separate requirements also requires us to
validate the hyperlinks in the HTML output
can be used to make a valid request
to obtain the desired output.

== Strategy

My TDD strategy for this exercise is to validate the integration of
all the requirements.
The test does not require us run a real web server
since the `httptest` package offers us the opportunity
to create a `Request` from a link in the HTML output
which we can use to validate the link itself.

My intention is not to implement Unit Tests for all elements.
Rather than focusing on the detail of the individual parts
I am focusing on the end result.

== Front end

I am not a front end web developer.

I expect the HTML output to be the bare minimum that satisfies the requirements:
a basic table with no borders and headers that contain fixed hyperlinks.

== Elements by ID

The integration test will extract elements from the table
by id so that we know the order is correct
and will then extract the URL from a known element
to then make an HTTP call and get the next result.

=== Leverage exercise 5.8

In exercise 5.8 we wrote a function `ElementByID`
to extract the correct elements by ID.

This will be the first part of the integration test:
given the HTML output
extract the elements of the table
and the links from the headers.

Not only HTML elements will have an ID, but their IDs will be generated
so that we can pick individual items and validate their position,
order, attributes, etc.

== Http Request

To avoid the need for a whole web server
just to validate the link in the table's headers,
we will instead simply assume a Request with the link and its parameters
was sent to us and we must now satisfy it.

We use the `httptest` package to create a Web Request
using the link in the header of each column.

We then get the `sort` attribute from the header,
sort the table by that value,
and validate the resulting html.

== Validating the sorted HTML

In this integration test,
I assume that the HTML produced by `PrintTracksAsHTML`
is the same whether this is the result of
printing it after ordering it by a column
or another.

A more robust test would compare the position within the table
of the elements with the same ID.

I'll leave that for a future improvement.