Creates basic read-only validation UI

** Why are these changes being introduced:

As part of allowing users to validate the actions taken by TACOS, we
need to first create an interface showing what those actions have been.

** Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/tco-8

** How does this address that need:

This commit creates a very basic interface to present what actions have
been taken with regard to a single term.

There is an index page, which shows all terms that have prompted any
activity (not all terms in the system).

From this index, the user can click into a display for any given term,
which will list all the detectors and categories in the system, with an
indication of which detectors activated for that term. The final score
for each category is also displayed.

There is not yet a form on this page, and the details of the UI need to
be more closely considered. This is a starting point, not the end.

** Document any side effects to this change:

This may be a side effect, or it may not, but: I've added the manage
role for Validations to the basic user, rather than creating a specific
role for this work. This is in line with what we've done so far, but I
am nervous about relying on basic roles for too much.

app/controllers/validation_controller.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class ValidationController < ApplicationController
+  def index
+    @terms = Term.joins(:detections).uniq
+  end
+
+  def term
+    @term = Term.find(params[:id])
+    @detectors = Detector.all
+    @categories = Category.all
+  end
+end

app/models/ability.rb

@@ -22,6 +22,10 @@ def initialize(user)
 
     # Allow all authenticated users to view reports
     can :view, :report
+
+    # Allow all authenticted users to perform validation work
+    can :manage, :validation
+    can :manage, Validation
     # End of Rules for all authenticated user with no additional roles required
 
     # Rules for admins

app/views/layouts/_site_nav.html.erb

@@ -13,6 +13,9 @@
             <% if can? :index, Term %>
               <%= link_to('Admin', admin_root_path, class: 'nav-item') %>
             <% end %>
+            <% if can? :index, Validation %>
+              <%= link_to('Validate', validate_path, class: 'nav-item') %>
+            <% end %>
             <% if can? :view, :playground %>
               <%= link_to('Playground', '/playground', class: 'nav-item') %>
             <% end %>

app/views/validation/index.html.erb

@@ -0,0 +1,23 @@
+<%= content_for(:title, "TACOS Validation") %>
+
+<h3>Validation index</h3>
+
+<p>This would be the page which lists terms - which have tripped a detector and have been categorized - which have not
+yet been validated by a user.</p>
+
+<table class="table table-simplified table-cozy">
+  <thead>
+    <tr>
+      <th scope="col">ID</th>
+      <th scope="col">Phrase</th>
+    </tr>
+  </thead>
+  <tbody>
+    <% @terms.each do |t| %>
+      <tr>
+        <td><%= t.id %></td>
+        <td><%= link_to(t.phrase, validate_term_path(t) ) %></td>
+      </tr>
+    <% end %>
+  </tbody>
+</table>

app/views/validation/term.html.erb

@@ -0,0 +1,63 @@
+<%= content_for(:title, "TACOS Validation") %>
+
+<p><%= link_to('Back to validation index', validate_path) %></p>
+
+<h3>Validation form</h3>
+
+<div class="well">
+  <p><%= @term.phrase %></p>
+</div>
+
+<p><strong>Please note:</strong> The information below is not currently filtered
+for only current detections; all detections across the history of the application
+are represented. This will need to be adjusted in the future.</p>
+
+<h4>Detection result</h4>
+
+<table class="table">
+  <thead>
+    <tr>
+      <th scope="col">Detector</th>
+      <th scope="col">Result</th>
+    </tr>
+  </thead>
+  <tbody>
+    <% @detectors.each do |d| %>
+      <tr class="detector-result">
+        <td><%= d.name %></td>
+        <td>
+          <% if @term.detections.pluck(:detector_id).include?(d.id) %>
+            Detection
+          <% else %>
+            &nbsp;
+          <% end %>
+        </td>
+      </tr>
+    <% end %>
+  </tbody>
+</table>
+
+<h4>Categorization result</h4>
+
+<table class="table">
+  <thead>
+    <tr>
+      <th scope="col">Category</th>
+      <th scope="col">Score</th>
+    </tr>
+  </thead>
+  <tbody>
+    <% @categories.each do |c| %>
+      <tr class="category-result">
+        <td><%= c.name %></td>
+        <td>
+        <% if @term.categorizations.pluck(:category_id).include?(c.id) %>
+          <%= @term.categorizations.find_by(category_id: c.id).confidence %>
+        <% else %>
+          &nbsp;
+        <% end %>
+        </td>
+      </tr>
+    <% end %>
+  </tbody>
+</table>

config/routes.rb

@@ -38,6 +38,10 @@
   get '/report', to: 'report#index'
   get '/report/algorithm_metrics', to: 'report#algorithm_metrics'
 
+  # Validation interface
+  get '/validate', to: 'validation#index'
+  get '/validate/:id', to: 'validation#term', as: 'validate_term'
+
   # Defines the root path route ("/")
   root to: 'static#index'
 end

test/controllers/validation_controller_test.rb

@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ValidationControllerTest < ActionDispatch::IntegrationTest
+  # Access to validation index
+  test 'validation index is not accessible without authentication' do
+    get validate_path
+
+    assert_redirected_to '/'
+    follow_redirect!
+
+    assert_select 'div.alert', text: 'Please sign in to continue', count: 1
+  end
+
+  test 'validation index is accessible to users with no special access' do
+    sign_in users(:basic)
+    get validate_path
+
+    assert_response :success
+  end
+
+  test 'validation index is accessible to users with the admin flag set' do
+    sign_in users(:admin)
+    get validate_path
+
+    assert_response :success
+  end
+
+  test 'unauthenticated users do not see a nav link to validation' do
+    get root_path
+
+    assert_select 'a.nav-item', text: 'Validate', count: 0
+  end
+
+  test 'Users with no special access do see a nav link to validation' do
+    sign_in users(:basic)
+    get root_path
+
+    assert_select 'a.nav-item', text: 'Validate', count: 1
+  end
+
+  test 'Users with the admin flag set do see a nav link to validation' do
+    sign_in users(:admin)
+    get root_path
+
+    assert_select 'a.nav-item', text: 'Validate', count: 1
+  end
+
+  # Access to validation form
+  test 'validation form is not accessible without authentication' do
+    get validate_term_path(terms(:hi))
+
+    assert_redirected_to '/'
+    follow_redirect!
+
+    assert_select 'div.alert', text: 'Please sign in to continue', count: 1
+  end
+
+  test 'validation form is accessible to users with no special access' do
+    sign_in users(:basic)
+    get validate_term_path(terms(:hi))
+
+    assert_response :success
+  end
+
+  test 'validation form is accessible to users with the admin flag set' do
+    sign_in users(:admin)
+    get validate_term_path(terms(:hi))
+
+    assert_response :success
+  end
+
+  # Validation form contents
+  test 'validation form includes a table row for every detector' do
+    sign_in users(:basic)
+    get validate_term_path(terms(:hi))
+
+    assert_select 'tr.detector-result', count: Detector.count
+  end
+
+  test 'validation form includes a table row for every category' do
+    sign_in users(:basic)
+    get validate_term_path(terms(:hi))
+
+    assert_select 'tr.category-result', count: Category.count
+  end
+end