Add specs

12 files changed, 904 insertions, 51 deletions

diff --git a/app/assets/javascripts/blob/pdf/index.js b/app/assets/javascripts/blob/pdf/index.js
index a74c2db9a61..9161be98853 100644
--- a/app/assets/javascripts/blob/pdf/index.js
+++ b/app/assets/javascripts/blob/pdf/index.js
@@ -31,7 +31,7 @@ export default () => {
       },
     },
     template: `
-      <div class="container-fluid md prepend-top-default append-bottom-default">
+      <div class="js-pdf-viewer container-fluid md prepend-top-default append-bottom-default">
         <div
           class="text-center loading"
           v-if="loading && !error">
diff --git a/app/models/blob.rb b/app/models/blob.rb
index 0df220b4983..e87b418d242 100644
--- a/app/models/blob.rb
+++ b/app/models/blob.rb
@@ -100,11 +100,11 @@ class Blob < SimpleDelegator
   end
 
   def valid_lfs_pointer?
-    lfs_pointer? && project.lfs_enabled?
+    lfs_pointer? && project&.lfs_enabled?
   end
 
   def invalid_lfs_pointer?
-    lfs_pointer? && !project.lfs_enabled?
+    lfs_pointer? && !project&.lfs_enabled?
   end
 
   def simple_viewer
diff --git a/app/models/blob_viewer/base.rb b/app/models/blob_viewer/base.rb
index d44d5c70fbb..d3674530273 100644
--- a/app/models/blob_viewer/base.rb
+++ b/app/models/blob_viewer/base.rb
@@ -56,10 +56,10 @@ module BlobViewer
     end
 
     def render_error
-      if override_max_size ? absolutely_too_large? : too_large?
-        :too_large
-      elsif server_side_but_stored_in_lfs?
+      if server_side_but_stored_in_lfs?
         :server_side_but_stored_in_lfs
+      elsif override_max_size ? absolutely_too_large? : too_large?
+        :too_large
       end
     end
 
diff --git a/spec/controllers/concerns/renders_blob_spec.rb b/spec/controllers/concerns/renders_blob_spec.rb
deleted file mode 100644
index 5f07afc5479..00000000000
--- a/spec/controllers/concerns/renders_blob_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-include 'spec_helper'
-
-describe Projects::BlobController, RendersBlob, model: true do
-  # TODO: Test
-end
diff --git a/spec/features/projects/blobs/blob_show_spec.rb b/spec/features/projects/blobs/blob_show_spec.rb
index 43af91882a4..aea9f66eec3 100644
--- a/spec/features/projects/blobs/blob_show_spec.rb
+++ b/spec/features/projects/blobs/blob_show_spec.rb
@@ -1,51 +1,314 @@
 require 'spec_helper'
 
-feature 'File blob', feature: true do
+feature 'File blob', :js, feature: true do
   include TreeHelper
+  include WaitForAjax
 
-  let(:project) { create(:project, :public, :test_repo) }
+  let(:project) { create(:project, :public) }
 
   def visit_blob(path, fragment = nil)
     visit namespace_project_blob_path(project.namespace, project, tree_join('master', path), anchor: fragment)
   end
 
-  context 'text files' do
-    it 'shows rendered output for SVG' do
-      visit_blob('files/images/wm.svg')
+  context 'Ruby file' do
+    before do
+      visit_blob('files/ruby/popen.rb')
 
-      expect(page).to have_selector('.blob-viewer[data-type="rich"]')
+      wait_for_ajax
     end
 
-    it 'switches to code view' do
-      visit_blob('files/images/wm.svg')
+    it 'displays the blob' do
+      aggregate_failures do
+        # shows highlighted Ruby code
+        expect(page).to have_content("require 'fileutils'")
 
-      first('.js-blob-viewer-switch-btn').click
+        # does not show a viewer switcher
+        expect(page).not_to have_selector('.js-blob-viewer-switcher')
 
-      expect(page).to have_selector('.blob-viewer[data-type="rich"]', visible: false)
-      expect(page).to have_selector('.blob-viewer[data-type="simple"]')
+        # shows an enabled copy button
+        expect(page).to have_selector('.js-copy-blob-source-btn:not(.disabled)')
+      end
     end
+  end
+
+  context 'Markdown file' do
+    context 'visiting directly' do
+      before do
+        visit_blob('files/markdown/ruby-style-guide.md')
+
+        wait_for_ajax
+      end
+
+      it 'displays the blob' do
+        aggregate_failures do
+          # hides the simple viewer
+          expect(page).to have_selector('.blob-viewer[data-type="simple"]', visible: false)
+          expect(page).to have_selector('.blob-viewer[data-type="rich"]')
+
+          # shows rendered Markdown
+          expect(page).to have_link("PEP-8")
+
+          # shows a viewer switcher
+          expect(page).to have_selector('.js-blob-viewer-switcher')
+
+          # shows a disabled copy button
+          expect(page).to have_selector('.js-copy-blob-source-btn.disabled')
+        end
+      end
+
+      context 'switching to the simple viewer' do
+        before do
+          find('.js-blob-viewer-switch-btn[data-viewer=simple]').click
+
+          wait_for_ajax
+        end
 
-    it 'opens raw mode when linking to a line in SVG file' do
-      visit_blob('files/images/wm.svg', 'L1')
+        it 'displays the blob' do
+          aggregate_failures do
+            # hides the rich viewer
+            expect(page).to have_selector('.blob-viewer[data-type="simple"]')
+            expect(page).to have_selector('.blob-viewer[data-type="rich"]', visible: false)
 
-      expect(page).to have_selector('#LC1.hll')
-      expect(page).to have_selector('.blob-viewer[data-type="simple"]')
+            # shows highlighted Markdown code
+            expect(page).to have_content("[PEP-8](http://www.python.org/dev/peps/pep-0008/)")
+
+            # shows an enabled copy button
+            expect(page).to have_selector('.js-copy-blob-source-btn:not(.disabled)')
+          end
+        end
+
+        context 'switching to the rich viewer again' do
+          before do
+            find('.js-blob-viewer-switch-btn[data-viewer=rich]').click
+
+            wait_for_ajax
+          end
+
+          it 'displays the blob' do
+            aggregate_failures do
+              # hides the simple viewer
+              expect(page).to have_selector('.blob-viewer[data-type="simple"]', visible: false)
+              expect(page).to have_selector('.blob-viewer[data-type="rich"]')
+
+              # shows an enabled copy button
+              expect(page).to have_selector('.js-copy-blob-source-btn:not(.disabled)')
+            end
+          end
+        end
+      end
     end
 
-    it 'opens raw mode when linking to a line in MD file' do
-      visit_blob('README.md', 'L1')
+    context 'visiting with a line number anchor' do
+      before do
+        visit_blob('files/markdown/ruby-style-guide.md', 'L1')
+
+        wait_for_ajax
+      end
+
+      it 'displays the blob' do
+        aggregate_failures do
+          # hides the rich viewer
+          expect(page).to have_selector('.blob-viewer[data-type="simple"]')
+          expect(page).to have_selector('.blob-viewer[data-type="rich"]', visible: false)
+
+          # highlights the line in question
+          expect(page).to have_selector('#LC1.hll')
+
+          # shows highlighted Markdown code
+          expect(page).to have_content("[PEP-8](http://www.python.org/dev/peps/pep-0008/)")
 
-      expect(page).to have_selector('#LC1.hll')
-      expect(page).to have_selector('.blob-viewer[data-type="simple"]')
+          # shows an enabled copy button
+          expect(page).to have_selector('.js-copy-blob-source-btn:not(.disabled)')
+        end
+      end
     end
   end
 
-  context 'binary files' do
-    it 'does not show view toggle buttons in toolbar' do
+  context 'Markdown file (stored in LFS)' do
+    before do
+      project.add_master(project.creator)
+
+      Files::CreateService.new(
+        project,
+        project.creator,
+        start_branch: 'master',
+        branch_name: 'master',
+        commit_message: "Add Markdown in LFS",
+        file_path: 'files/lfs/file.md',
+        file_content: project.repository.blob_at('master', 'files/lfs/lfs_object.iso').data
+      ).execute
+    end
+
+    context 'when LFS is enabled on the project' do
+      before do
+        allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
+        project.update_attribute(:lfs_enabled, true)
+
+        visit_blob('files/lfs/file.md')
+
+        wait_for_ajax
+      end
+
+      it 'displays the blob' do
+        aggregate_failures do
+          # hides the simple viewer
+          expect(page).to have_selector('.blob-viewer[data-type="simple"]', visible: false)
+          expect(page).to have_selector('.blob-viewer[data-type="rich"]')
+
+          # shows an error message
+          expect(page).to have_content('The rendered file could not be displayed because it is stored in LFS. You can view the source or download it instead.')
+
+          # shows a viewer switcher
+          expect(page).to have_selector('.js-blob-viewer-switcher')
+
+          # does not show a copy button
+          expect(page).not_to have_selector('.js-copy-blob-source-btn')
+        end
+      end
+
+      context 'switching to the simple viewer' do
+        before do
+          find('.js-blob-viewer-switcher .js-blob-viewer-switch-btn[data-viewer=simple]').click
+
+          wait_for_ajax
+        end
+
+        it 'displays the blob' do
+          aggregate_failures do
+            # hides the rich viewer
+            expect(page).to have_selector('.blob-viewer[data-type="simple"]')
+            expect(page).to have_selector('.blob-viewer[data-type="rich"]', visible: false)
+
+            # shows an error message
+            expect(page).to have_content('The source could not be displayed because it is stored in LFS. You can download it instead.')
+
+            # does not show a copy button
+            expect(page).not_to have_selector('.js-copy-blob-source-btn')
+          end
+        end
+      end
+    end
+
+    context 'when LFS is disabled on the project' do
+      before do
+        visit_blob('files/lfs/file.md')
+
+        wait_for_ajax
+      end
+
+      it 'displays the blob' do
+        aggregate_failures do
+          # shows text
+          expect(page).to have_content('size 1575078')
+
+          # does not show a viewer switcher
+          expect(page).not_to have_selector('.js-blob-viewer-switcher')
+
+          # shows an enabled copy button
+          expect(page).to have_selector('.js-copy-blob-source-btn:not(.disabled)')
+        end
+      end
+    end
+  end
+
+  context 'PDF file' do
+    before do
+      project.add_master(project.creator)
+
+      Files::CreateService.new(
+        project,
+        project.creator,
+        start_branch: 'master',
+        branch_name: 'master',
+        commit_message: "Add PDF",
+        file_path: 'files/test.pdf',
+        file_content: File.read(Rails.root.join('spec/javascripts/blob/pdf/test.pdf'))
+      ).execute
+
+      visit_blob('files/test.pdf')
+
+      wait_for_ajax
+    end
+
+    it 'displays the blob' do
+      aggregate_failures do
+        # shows rendered PDF
+        expect(page).to have_selector('.js-pdf-viewer')
+
+        # does not show a viewer switcher
+        expect(page).not_to have_selector('.js-blob-viewer-switcher')
+
+        # does not show a copy button
+        expect(page).not_to have_selector('.js-copy-blob-source-btn')
+      end
+    end
+  end
+
+  context 'ISO file (stored in LFS)' do
+    context 'when LFS is enabled on the project' do
+      before do
+        allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
+        project.update_attribute(:lfs_enabled, true)
+
+        visit_blob('files/lfs/lfs_object.iso')
+
+        wait_for_ajax
+      end
+
+      it 'displays the blob' do
+        aggregate_failures do
+          # shows a download link
+          expect(page).to have_link('Download (1.5 MB)')
+
+          # does not show a viewer switcher
+          expect(page).not_to have_selector('.js-blob-viewer-switcher')
+
+          # does not show a copy button
+          expect(page).not_to have_selector('.js-copy-blob-source-btn')
+        end
+      end
+    end
+
+    context 'when LFS is disabled on the project' do
+      before do
+        visit_blob('files/lfs/lfs_object.iso')
+
+        wait_for_ajax
+      end
+
+      it 'displays the blob' do
+        aggregate_failures do
+          # shows text
+          expect(page).to have_content('size 1575078')
+
+          # does not show a viewer switcher
+          expect(page).not_to have_selector('.js-blob-viewer-switcher')
+
+          # shows an enabled copy button
+          expect(page).to have_selector('.js-copy-blob-source-btn:not(.disabled)')
+        end
+      end
+    end
+  end
+
+  context 'ZIP file' do
+    before do
       visit_blob('Gemfile.zip')
 
-      expect(first('.file-actions .btn-group')).to have_selector('.btn', count: 1)
-      expect(first('.file-actions .btn-group .btn')[:title]).to eq('Download blob')
+      wait_for_ajax
+    end
+
+    it 'displays the blob' do
+      aggregate_failures do
+        # shows a download link
+        expect(page).to have_link('Download (2.11 KB)')
+
+        # does not show a viewer switcher
+        expect(page).not_to have_selector('.js-blob-viewer-switcher')
+
+        # does not show a copy button
+        expect(page).not_to have_selector('.js-copy-blob-source-btn')
+      end
     end
   end
 end
diff --git a/spec/helpers/blob_helper_spec.rb b/spec/helpers/blob_helper_spec.rb
index 292bc0d68fd..d9154ec8152 100644
--- a/spec/helpers/blob_helper_spec.rb
+++ b/spec/helpers/blob_helper_spec.rb
@@ -104,4 +104,114 @@ describe BlobHelper do
       expect(Capybara.string(link).find_link('Edit')[:href]).to eq('/gitlab/gitlabhq/edit/master/README.md?mr_id=10')
     end
   end
+
+  context 'viewer related' do
+    include FakeBlobHelpers
+
+    let(:project) { build(:empty_project) }
+
+    let(:viewer_class) do
+      Class.new(BlobViewer::Base) do
+        self.max_size = 1.megabyte
+        self.absolute_max_size = 5.megabytes
+        self.type = :rich
+        self.client_side = false
+      end
+    end
+
+    let(:viewer) { viewer_class.new(blob) }
+    let(:blob) { fake_blob }
+
+    before do
+      assign(:project, project)
+      assign(:id, File.join('master', blob.path))
+
+      controller.params[:controller] = 'projects/blob'
+      controller.params[:action] = 'show'
+      controller.params[:namespace_id] = project.namespace.to_param
+      controller.params[:project_id] = project.to_param
+      controller.params[:id] = File.join('master', blob.path)
+    end
+
+    describe '#blob_render_error_reason' do
+      context 'for error :too_large' do
+        context 'when the blob size is larger than the absolute max size' do
+          let(:blob) { fake_blob(size: 10.megabytes) }
+
+          it 'returns an error message' do
+            expect(helper.blob_render_error_reason(viewer, :too_large)).to eq('it is larger than 5 MB')
+          end
+        end
+
+        context 'when the blob size is larger than the max size' do
+          let(:blob) { fake_blob(size: 2.megabytes) }
+
+          it 'returns an error message' do
+            expect(helper.blob_render_error_reason(viewer, :too_large)).to eq('it is larger than 1 MB')
+          end
+        end
+      end
+
+      context 'for error :server_side_but_stored_in_lfs' do
+        it 'returns an error message' do
+          expect(helper.blob_render_error_reason(viewer, :server_side_but_stored_in_lfs)).to eq('it is stored in LFS')
+        end
+      end
+    end
+
+    describe '#blob_render_error_options' do
+      context 'for error :too_large' do
+        context 'when the max size can be overridden' do
+          let(:blob) { fake_blob(size: 2.megabytes) }
+
+          it 'includes a "load it anyway" link' do
+            expect(helper.blob_render_error_options(viewer, :too_large)).to include(/load it anyway/)
+          end
+        end
+
+        context 'when the max size cannot be overridden' do
+          let(:blob) { fake_blob(size: 10.megabytes) }
+
+          it 'does not include a "load it anyway" link' do
+            expect(helper.blob_render_error_options(viewer, :too_large)).not_to include(/load it anyway/)
+          end
+        end
+      end
+
+      context 'when the viewer is rich' do
+        context 'the blob is rendered as text' do
+          let(:blob) { fake_blob(path: 'file.md') }
+
+          it 'includes a "view the source" link' do
+            expect(helper.blob_render_error_options(viewer, :server_side_but_stored_in_lfs)).to include(/view the source/)
+          end
+        end
+
+        context 'the blob is not rendered as text' do
+          let(:blob) { fake_blob(path: 'file.pdf', binary: true) }
+
+          it 'does not include a "view the source" link' do
+            expect(helper.blob_render_error_options(viewer, :server_side_but_stored_in_lfs)).not_to include(/view the source/)
+          end
+        end
+      end
+
+
+      context 'when the viewer is not rich' do
+        before do
+          viewer_class.type = :simple
+        end
+
+        let(:blob) { fake_blob(path: 'file.md') }
+
+        it 'does not include a "view the source" link' do
+          expect(helper.blob_render_error_options(viewer, :server_side_but_stored_in_lfs)).not_to include(/view the source/)
+        end
+      end
+
+      it 'includes a "download it" link' do
+        expect(helper.blob_render_error_options(viewer, :server_side_but_stored_in_lfs)).to include(/download it/)
+      end
+    end
+  end
 end
diff --git a/spec/models/blob_spec.rb b/spec/models/blob_spec.rb
index fd42a87c37e..80dcfeeb3b5 100644
--- a/spec/models/blob_spec.rb
+++ b/spec/models/blob_spec.rb
@@ -2,6 +2,14 @@
 require 'rails_helper'
 
 describe Blob do
+  include FakeBlobHelpers
+
+  let(:project) { build(:empty_project, lfs_enabled: true) }
+
+  before do
+    allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
+  end
+
   describe '.decorate' do
     it 'returns NilClass when given nil' do
       expect(described_class.decorate(nil)).to be_nil
@@ -12,7 +20,7 @@ describe Blob do
     context 'using a binary blob' do
       it 'returns the data as-is' do
         data = "\n\xFF\xB9\xC3"
-        blob = described_class.new(double(binary?: true, data: data))
+        blob = fake_blob(binary: true, data: data)
 
         expect(blob.data).to eq(data)
       end
@@ -20,12 +28,176 @@ describe Blob do
 
     context 'using a text blob' do
       it 'converts the data to UTF-8' do
-        blob = described_class.new(double(binary?: false, data: "\n\xFF\xB9\xC3"))
+        blob = fake_blob(binary: false, data: "\n\xFF\xB9\xC3")
 
         expect(blob.data).to eq("\n���")
       end
     end
   end
 
-  # TODO: Test new methods
+  describe '#raw_binary?' do
+    context 'if the blob is a valid LFS pointer' do
+      context 'if the extension has a rich viewer' do
+        context 'if the viewer is binary' do
+          it 'return true' do
+            blob = fake_blob(path: 'file.pdf', lfs: true)
+
+            expect(blob.raw_binary?).to be_truthy
+          end
+        end
+
+        context 'if the viewer is text-based' do
+          it 'return false' do
+            blob = fake_blob(path: 'file.md', lfs: true)
+
+            expect(blob.raw_binary?).to be_falsey
+          end
+        end
+      end
+
+      context "if the extension doesn't have a rich viewer" do
+        it 'returns true' do
+          blob = fake_blob(path: 'file.exe', lfs: true)
+
+          expect(blob.raw_binary?).to be_truthy
+        end
+      end
+    end
+
+    context 'if the blob is not an LFS pointer' do
+      context 'if the blob is binary' do
+        it 'return true' do
+          blob = fake_blob(path: 'file.pdf', binary: true)
+
+          expect(blob.raw_binary?).to be_truthy
+        end
+      end
+
+      context 'if the blob is text-based' do
+        it 'return false' do
+          blob = fake_blob(path: 'file.md')
+
+          expect(blob.raw_binary?).to be_falsey
+        end
+      end
+    end
+  end
+
+  describe '#extension' do
+    it 'returns the extension' do
+      blob = fake_blob(path: 'file.md')
+
+      expect(blob.extension).to eq('md')
+    end
+  end
+
+  describe '#simple_viewer' do
+    context 'when the blob is empty' do
+      it 'returns an empty viewer' do
+        blob = fake_blob(data: '')
+
+        expect(blob.simple_viewer).to be_a(BlobViewer::Empty)
+      end
+    end
+
+    context 'when the file represented by the blob is binary' do
+      it 'returns a download viewer' do
+        blob = fake_blob(binary: true)
+
+        expect(blob.simple_viewer).to be_a(BlobViewer::Download)
+      end
+    end
+
+    context 'when the file represented by the blob is text-based' do
+      it 'returns a text viewer' do
+        blob = fake_blob
+
+        expect(blob.simple_viewer).to be_a(BlobViewer::Text)
+      end
+    end
+  end
+
+  describe '#rich_viewer' do
+    context 'when the blob is an invalid LFS pointer' do
+      before do
+        project.lfs_enabled = false
+      end
+
+      it 'returns nil' do
+        blob = fake_blob(path: 'file.pdf', lfs: true)
+
+        expect(blob.rich_viewer).to be_nil
+      end
+    end
+
+    context 'when the blob is empty' do
+      it 'returns nil' do
+        blob = fake_blob(data: '')
+
+        expect(blob.rich_viewer).to be_nil
+      end
+    end
+
+    context 'when the blob is a valid LFS pointer' do
+      it 'returns a matching viewer' do
+        blob = fake_blob(path: 'file.pdf', lfs: true)
+
+        expect(blob.rich_viewer).to be_a(BlobViewer::PDF)
+      end
+    end
+
+    context 'when the blob is binary' do
+      it 'returns a matching binary viewer' do
+        blob = fake_blob(path: 'file.pdf', binary: true)
+
+        expect(blob.rich_viewer).to be_a(BlobViewer::PDF)
+      end
+    end
+
+    context 'when the blob is text-based' do
+      it 'returns a matching text-based viewer' do
+        blob = fake_blob(path: 'file.md')
+
+        expect(blob.rich_viewer).to be_a(BlobViewer::Markup)
+      end
+    end
+  end
+
+  describe '#rendered_as_text?' do
+    context 'when ignoring errors' do
+      context 'when the simple viewer is text-based' do
+        it 'returns true' do
+          blob = fake_blob(path: 'file.md', size: 100.megabytes)
+
+          expect(blob.rendered_as_text?).to be_truthy
+        end
+      end
+
+      context 'when the simple viewer is binary' do
+        it 'returns false' do
+          blob = fake_blob(path: 'file.pdf', binary: true, size: 100.megabytes)
+
+          expect(blob.rendered_as_text?).to be_falsey
+        end
+      end
+    end
+
+    context 'when not ignoring errors' do
+      context 'when the viewer has render errors' do
+        it 'returns false' do
+          blob = fake_blob(path: 'file.md', size: 100.megabytes)
+
+          expect(blob.rendered_as_text?(ignore_errors: false)).to be_falsey
+        end
+      end
+
+      context "when the viewer doesn't have render errors" do
+        it 'returns true' do
+          blob = fake_blob(path: 'file.md')
+
+          expect(blob.rendered_as_text?(ignore_errors: false)).to be_truthy
+        end
+      end
+    end
+  end
 end
diff --git a/spec/models/blob_viewer/base_spec.rb b/spec/models/blob_viewer/base_spec.rb
index e176d9c751b..a3e598de56d 100644
--- a/spec/models/blob_viewer/base_spec.rb
+++ b/spec/models/blob_viewer/base_spec.rb
@@ -1,5 +1,186 @@
-include 'spec_helper'
+require 'spec_helper'
 
 describe BlobViewer::Base, model: true do
-  # TODO: Test
+  include FakeBlobHelpers
+
+  let(:project) { build(:empty_project) }
+
+  let(:viewer_class) do
+    Class.new(described_class) do
+      self.extensions = %w(pdf)
+      self.max_size = 1.megabyte
+      self.absolute_max_size = 5.megabytes
+      self.client_side = false
+    end
+  end
+
+  let(:viewer) { viewer_class.new(blob) }
+
+  describe '.can_render?' do
+    context 'when the extension is supported' do
+      let(:blob) { fake_blob(path: 'file.pdf') }
+
+      it 'returns true' do
+        expect(viewer_class.can_render?(blob)).to be_truthy
+      end
+    end
+
+    context 'when the extension is not supported' do
+      let(:blob) { fake_blob(path: 'file.txt') }
+
+      it 'returns false' do
+        expect(viewer_class.can_render?(blob)).to be_falsey
+      end
+    end
+  end
+
+  describe '#too_large?' do
+    context 'when the blob size is larger than the max size' do
+      let(:blob) { fake_blob(path: 'file.pdf', size: 2.megabytes) }
+
+      it 'returns true' do
+        expect(viewer.too_large?).to be_truthy
+      end
+    end
+
+    context 'when the blob size is smaller than the max size' do
+      let(:blob) { fake_blob(path: 'file.pdf', size: 10.kilobytes) }
+
+      it 'returns false' do
+        expect(viewer.too_large?).to be_falsey
+      end
+    end
+  end
+
+  describe '#absolutely_too_large?' do
+    context 'when the blob size is larger than the absolute max size' do
+      let(:blob) { fake_blob(path: 'file.pdf', size: 10.megabytes) }
+
+      it 'returns true' do
+        expect(viewer.absolutely_too_large?).to be_truthy
+      end
+    end
+
+    context 'when the blob size is smaller than the absolute max size' do
+      let(:blob) { fake_blob(path: 'file.pdf', size: 2.megabytes) }
+
+      it 'returns false' do
+        expect(viewer.absolutely_too_large?).to be_falsey
+      end
+    end
+  end
+
+  describe '#can_override_max_size?' do
+    context 'when the blob size is larger than the max size' do
+      context 'when the blob size is larger than the absolute max size' do
+        let(:blob) { fake_blob(path: 'file.pdf', size: 10.megabytes) }
+
+        it 'returns false' do
+          expect(viewer.can_override_max_size?).to be_falsey
+        end
+      end
+
+      context 'when the blob size is smaller than the absolute max size' do
+        let(:blob) { fake_blob(path: 'file.pdf', size: 2.megabytes) }
+
+        it 'returns true' do
+          expect(viewer.can_override_max_size?).to be_truthy
+        end
+      end
+    end
+
+    context 'when the blob size is smaller than the max size' do
+      let(:blob) { fake_blob(path: 'file.pdf', size: 10.kilobytes) }
+
+      it 'returns false' do
+        expect(viewer.can_override_max_size?).to be_falsey
+      end
+    end
+  end
+
+  describe '#render_error' do
+    context 'when the max size is overridden' do
+      before do
+        viewer.override_max_size = true
+      end
+
+      context 'when the blob size is larger than the absolute max size' do
+        let(:blob) { fake_blob(path: 'file.pdf', size: 10.megabytes) }
+
+        it 'returns :too_large' do
+          expect(viewer.render_error).to eq(:too_large)
+        end
+      end
+
+      context 'when the blob size is smaller than the absolute max size' do
+        let(:blob) { fake_blob(path: 'file.pdf', size: 2.megabytes) }
+
+        it 'returns nil' do
+          expect(viewer.render_error).to be_nil
+        end
+      end
+    end
+
+    context 'when the max size is not overridden' do
+      context 'when the blob size is larger than the max size' do
+        let(:blob) { fake_blob(path: 'file.pdf', size: 2.megabytes) }
+
+        it 'returns :too_large' do
+          expect(viewer.render_error).to eq(:too_large)
+        end
+      end
+
+      context 'when the blob size is smaller than the max size' do
+        let(:blob) { fake_blob(path: 'file.pdf', size: 10.kilobytes) }
+
+        it 'returns nil' do
+          expect(viewer.render_error).to be_nil
+        end
+      end
+    end
+
+    context 'when the viewer is server side but the blob is stored in LFS' do
+      let(:project) { build(:empty_project, lfs_enabled: true) }
+
+      let(:blob) { fake_blob(path: 'file.pdf', lfs: true) }
+
+      before do
+        allow(Gitlab.config.lfs).to receive(:enabled).and_return(true)
+      end
+
+      it 'return :server_side_but_stored_in_lfs' do
+        expect(viewer.render_error).to eq(:server_side_but_stored_in_lfs)
+      end
+    end
+  end
+
+  describe '#prepare!' do
+    context 'when the viewer is server side' do
+      let(:blob) { fake_blob(path: 'file.md') }
+
+      before do
+        viewer_class.client_side = false
+      end
+
+      it 'loads all blob data' do
+        expect(blob).to receive(:load_all_data!)
+
+        viewer.prepare!
+      end
+    end
+
+    context 'when the viewer is client side' do
+      let(:blob) { fake_blob(path: 'file.md') }
+
+      before do
+        viewer_class.client_side = true
+      end
+
+      it "doesn't load all blob data" do
+        expect(blob).not_to receive(:load_all_data!)
+
+        viewer.prepare!
+      end
+    end
+  end
 end
diff --git a/spec/support/helpers/fake_blob_helpers.rb b/spec/support/helpers/fake_blob_helpers.rb
new file mode 100644
index 00000000000..b29af732ad3
--- /dev/null
+++ b/spec/support/helpers/fake_blob_helpers.rb
@@ -0,0 +1,50 @@
+module FakeBlobHelpers
+  class FakeBlob
+    include Linguist::BlobHelper
+
+    attr_reader :path, :size, :data, :lfs_oid, :lfs_size
+
+    def initialize(path: 'file.txt', size: 1.kilobyte, data: 'foo', binary: false, lfs: nil)
+      @path = path
+      @size = size
+      @data = data
+      @binary = binary
+
+      @lfs_pointer = lfs.present?
+      if @lfs_pointer
+        @lfs_oid = SecureRandom.hex(20)
+        @lfs_size = 1.megabyte
+      end
+    end
+
+    alias_method :name, :path
+
+    def mode
+      nil
+    end
+
+    def id
+      0
+    end
+
+    def binary?
+      @binary
+    end
+
+    def load_all_data!(repository)
+      # No-op
+    end
+
+    def lfs_pointer?
+      @lfs_pointer
+    end
+
+    def truncated?
+      false
+    end
+  end
+
+  def fake_blob(**kwargs)
+    Blob.decorate(FakeBlob.new(**kwargs), project)
+  end
+end
diff --git a/spec/views/projects/blob/_render_error.html.haml_spec.rb b/spec/views/projects/blob/_render_error.html.haml_spec.rb
deleted file mode 100644
index fabd444a6ad..00000000000
--- a/spec/views/projects/blob/_render_error.html.haml_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require 'spec_helper'
-
-describe 'app/views/projects/blob/_render_error.html.haml' do
-  # TODO: Test
-end
diff --git a/spec/views/projects/blob/_viewer.html.haml_spec.rb b/spec/views/projects/blob/_viewer.html.haml_spec.rb
index 1d2055c10fc..c790dc79b0a 100644
--- a/spec/views/projects/blob/_viewer.html.haml_spec.rb
+++ b/spec/views/projects/blob/_viewer.html.haml_spec.rb
@@ -1,5 +1,97 @@
 require 'spec_helper'
 
-describe 'app/views/projects/blob/_viewer.html.haml' do
-  # TODO: Test
+describe 'projects/blob/_viewer.html.haml', :view do
+  include FakeBlobHelpers
+
+  let(:project) { build(:empty_project) }
+
+  let(:viewer_class) do
+    Class.new(BlobViewer::Base) do
+      include BlobViewer::Rich
+
+      self.partial_name = 'text'
+      self.max_size = 1.megabyte
+      self.absolute_max_size = 5.megabytes
+      self.client_side = false
+    end
+  end
+
+  let(:viewer) { viewer_class.new(blob) }
+  let(:blob) { fake_blob }
+
+  before do
+    assign(:project, project)
+    assign(:id, File.join('master', blob.path))
+
+    controller.params[:controller] = 'projects/blob'
+    controller.params[:action] = 'show'
+    controller.params[:namespace_id] = project.namespace.to_param
+    controller.params[:project_id] = project.to_param
+    controller.params[:id] = File.join('master', blob.path)
+  end
+
+  def render_view
+    render partial: 'projects/blob/viewer', locals: { viewer: viewer }
+  end
+
+  context 'when the viewer is server side' do
+    before do
+      viewer_class.client_side = false
+    end
+
+    context 'when there is no render error' do
+      it 'adds a URL to the blob viewer element' do
+        render_view
+
+
+        expect(rendered).to have_css('.blob-viewer[data-url]')
+      end
+
+      it 'displays a spinner' do
+        render_view
+
+        expect(rendered).to have_css('i[aria-label="Loading content"]')
+      end
+    end
+
+    context 'when there is a render error' do
+      let(:blob) { fake_blob(size: 10.megabytes) }
+
+      it 'renders the error' do
+        render_view
+
+        expect(view).to render_template('projects/blob/_render_error')
+      end
+    end
+  end
+
+  context 'when the viewer is client side' do
+    before do
+      viewer_class.client_side = true
+    end
+
+    context 'when there is no render error' do
+      it 'prepares the viewer' do
+        expect(viewer).to receive(:prepare!)
+
+        render_view
+      end
+
+      it 'renders the viewer' do
+        render_view
+
+        expect(view).to render_template('projects/blob/viewers/_text')
+      end
+    end
+
+    context 'when there is a render error' do
+      let(:blob) { fake_blob(size: 10.megabytes) }
+
+      it 'renders the error' do
+        render_view
+
+        expect(view).to render_template('projects/blob/_render_error')
+      end
+    end
+  end
 end
diff --git a/spec/views/projects/blob/_viewer_switcher.html.haml_spec.rb b/spec/views/projects/blob/_viewer_switcher.html.haml_spec.rb
deleted file mode 100644
index 337f40d50df..00000000000
--- a/spec/views/projects/blob/_viewer_switcher.html.haml_spec.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-require 'spec_helper'
-
-describe 'app/views/projects/blob/_viewer_switcher.html.haml' do
-  # TODO: Test
-end