Create have_a_valid_manifest matcher

common/spec/spec_helper_foot.rb

@@ -397,3 +397,31 @@ def sort(x)
     "expected no dependency to be created from #{expected.inspect}"
   end
 end
+
+RSpec::Matchers.define :have_a_valid_manifest do
+  match do |actual|
+    manifest_lines = File.readlines(actual + '.manifest').map(&:chomp).reject(&:empty?)
+    gemspec_lines = eval(File.read(actual + '.gemspec'), binding, actual + '.gemspec').files
+
+    @missing_from_manifest = gemspec_lines - manifest_lines
+    @extra_in_manifest = manifest_lines - gemspec_lines
+
+    @missing_from_manifest.empty? && @extra_in_manifest.empty?
+  end
+
+  description do
+    'have a valid manifest'
+  end
+
+  failure_message do |_actual|
+    reasons = []
+    if @missing_from_manifest.any?
+      reasons << "file(s) missing from manifest (#{@missing_from_manifest.join(', ')})"
+    end
+    if @extra_in_manifest.any?
+      reasons << "file(s) extra in manifest (#{@extra_in_manifest.join(', ')})"
+    end
+
+    "expected manifest to be valid (problems: #{reasons.join(' and ')})"
+  end
+end

nanoc-external/spec/manifest_spec.rb

@@ -1,22 +1,7 @@
 # frozen_string_literal: true
 
 describe 'manifest', chdir: false do
-  let(:manifest_lines) do
-    File.readlines('nanoc-external.manifest').map(&:chomp).reject(&:empty?)
-  end
-
-  let(:gemspec_lines) do
-    gemspec = eval(File.read('nanoc-external.gemspec'), binding, 'nanoc-external.gemspec')
-    gemspec.files
-  end
-
-  it 'contains all files in gemspec' do
-    missing_from_manifest = gemspec_lines - manifest_lines
-    expect(missing_from_manifest).to be_empty, "Found files that appear in the gemspec, but not in the manifest: #{missing_from_manifest.join(', ')}"
-  end
-
-  it 'contains no files not in gemspec' do
-    extra_in_manifest = manifest_lines - gemspec_lines
-    expect(extra_in_manifest).to be_empty, "Found files that appear in the manifest, but not in the gemspec: #{extra_in_manifest.join(', ')}"
+  example do
+    expect('nanoc-external').to have_a_valid_manifest
   end
 end

nanoc-live/spec/manifest_spec.rb

@@ -1,22 +1,7 @@
 # frozen_string_literal: true
 
 describe 'manifest', chdir: false do
-  let(:manifest_lines) do
-    File.readlines('nanoc-live.manifest').map(&:chomp).reject(&:empty?)
-  end
-
-  let(:gemspec_lines) do
-    gemspec = eval(File.read('nanoc-live.gemspec'), binding, 'nanoc-live.gemspec')
-    gemspec.files
-  end
-
-  it 'contains all files in gemspec' do
-    missing_from_manifest = gemspec_lines - manifest_lines
-    expect(missing_from_manifest).to be_empty, "Found files that appear in the gemspec, but not in the manifest: #{missing_from_manifest.join(', ')}"
-  end
-
-  it 'contains no files not in gemspec' do
-    extra_in_manifest = manifest_lines - gemspec_lines
-    expect(extra_in_manifest).to be_empty, "Found files that appear in the manifest, but not in the gemspec: #{extra_in_manifest.join(', ')}"
+  example do
+    expect('nanoc-live').to have_a_valid_manifest
   end
 end

nanoc/spec/manifest_spec.rb

@@ -1,22 +1,7 @@
 # frozen_string_literal: true
 
 describe 'manifest', chdir: false do
-  let(:manifest_lines) do
-    File.readlines('nanoc.manifest').map(&:chomp).reject(&:empty?)
-  end
-
-  let(:gemspec_lines) do
-    gemspec = eval(File.read('nanoc.gemspec'), binding, 'nanoc.gemspec')
-    gemspec.files
-  end
-
-  it 'contains all files in gemspec' do
-    missing_from_manifest = gemspec_lines - manifest_lines
-    expect(missing_from_manifest).to be_empty, "Found files that appear in the gemspec, but not in the manifest: #{missing_from_manifest.join(', ')}"
-  end
-
-  it 'contains no files not in gemspec' do
-    extra_in_manifest = manifest_lines - gemspec_lines
-    expect(extra_in_manifest).to be_empty, "Found files that appear in the manifest, but not in the gemspec: #{extra_in_manifest.join(', ')}"
+  example do
+    expect('nanoc').to have_a_valid_manifest
   end
 end