1 files changed, 127 insertions, 0 deletions
diff --git a/gems/ipynbdiff/spec/ipynb_diff_spec.rb b/gems/ipynbdiff/spec/ipynb_diff_spec.rb
new file mode 100644
index 00000000000..3ca092aaf5c
--- /dev/null
+++ b/gems/ipynbdiff/spec/ipynb_diff_spec.rb
@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+require_relative 'test_helper'
+
+describe IpynbDiff do
+  def diff_signs(diff)
+    diff.to_s(:text).scan(/.*\n/).map { |l| l[0] }.join('')
+  end
+
+  describe '.diff' do
+    let(:from_path) { FROM_PATH }
+    let(:to_path) { TO_PATH }
+    let(:from) { File.read(from_path) }
+    let(:to) { File.read(to_path) }
+    let(:include_frontmatter) { false }
+    let(:hide_images) { false }
+
+    subject { described_class.diff(from, to, include_frontmatter: include_frontmatter, hide_images: hide_images) }
+
+    context 'if preprocessing is active' do
+      it { is_expected.not_to include('<td>') }
+    end
+
+    context 'when to is nil' do
+      let(:to) { nil }
+      let(:from_path) { test_case_input_path('only_md') }
+
+      it 'all lines are removals' do
+        expect(diff_signs(subject)).to eq('-----')
+      end
+    end
+
+    context 'when from is nil' do
+      let(:from) { nil }
+      let(:to_path) { test_case_input_path('only_md') }
+
+      it 'all lines are additions' do
+        expect(diff_signs(subject)).to eq('+++++')
+      end
+    end
+
+    context 'when include_frontmatter is true' do
+      let(:include_frontmatter) { true }
+
+      it 'shows changes metadata in the metadata' do
+        expect(subject.to_s(:text)).to include('+    display_name: New Python 3 (ipykernel)')
+      end
+    end
+
+    context 'when hide_images is true' do
+      let(:hide_images) { true }
+
+      it 'hides images' do
+        expect(subject.to_s(:text)).to include('     [Hidden Image Output]')
+      end
+    end
+
+    context 'when include_frontmatter is false' do
+      it 'drops metadata from the diff' do
+        expect(subject.to_s(:text)).not_to include('+    display_name: New Python 3 (ipykernel)')
+      end
+    end
+
+    context 'when either notebook can not be processed' do
+      using RSpec::Parameterized::TableSyntax
+
+      where(:ctx, :from, :to) do
+        'because from is invalid'                 | 'a' | nil
+        'because from does not have the cell tag' | '{"metadata":[]}' | nil
+        'because to is invalid'                   | nil | 'a'
+        'because to does not have the cell tag'   | nil | '{"metadata":[]}'
+      end
+
+      with_them do
+        it { is_expected.to be_nil }
+      end
+    end
+  end
+
+  describe '.transform' do
+    let(:notebook) { FROM_IPYNB }
+    let(:include_frontmatter) { false }
+    let(:hide_images) { false }
+
+    subject do
+      described_class.transform(notebook,
+        include_frontmatter: include_frontmatter,
+        hide_images: hide_images)
+    end
+
+    describe 'error cases' do
+      using RSpec::Parameterized::TableSyntax
+
+      where(:ctx, :notebook) do
+        'notebook is nil' | nil
+        'notebook is invalid' | 'a'
+        'notebook does not have cell' | '{"metadata":[]}'
+      end
+
+      with_them do
+        it { is_expected.to be_nil }
+      end
+    end
+
+    describe 'options' do
+      context 'when include_frontmatter is false' do
+        it { is_expected.not_to include('display_name: Python 3 (ipykernel)') }
+      end
+
+      context 'when include_frontmatter is true' do
+        let(:include_frontmatter) { true }
+
+        it { is_expected.to include('display_name: Python 3 (ipykernel)') }
+      end
+
+      context 'when hide_images is false' do
+        it { is_expected.not_to include('[Hidden Image Output]') }
+      end
+
+      context 'when hide_images is true' do
+        let(:hide_images) { true }
+
+        it { is_expected.to include('    [Hidden Image Output]') }
+      end
+    end
+  end
+end