diff --git a/frontend/components/DefinitionSources/DefinitionSources.tsx b/frontend/components/DefinitionSources/DefinitionSources.tsx
index 55a0453..c80745e 100644
--- a/frontend/components/DefinitionSources/DefinitionSources.tsx
+++ b/frontend/components/DefinitionSources/DefinitionSources.tsx
@@ -144,9 +144,7 @@ const DefinitionSourceTr: FC<DefinitionSourceTrProps> = ({ source, combinedDefin
             <div>
               {source.modules.map((module, index) => (
                 <Text key={index} as="div" whiteSpace="nowrap">
-                  <Link to={path.modules.show(source.modules.slice(0, index + 1).map((mod) => mod.moduleName))}>
-                    {module.moduleName}
-                  </Link>
+                  <Link to={path.modules.show(source.modules.slice(0, index + 1))}>{module}</Link>
                 </Text>
               ))}
             </div>
diff --git a/frontend/components/DotMetadataDialog/DotMetadataDialog.tsx b/frontend/components/DotMetadataDialog/DotMetadataDialog.tsx
index 678451d..85e5d9e 100644
--- a/frontend/components/DotMetadataDialog/DotMetadataDialog.tsx
+++ b/frontend/components/DotMetadataDialog/DotMetadataDialog.tsx
@@ -103,7 +103,7 @@ const SourceDotMetadataContent: FC<{ dotMetadata: DotSourceMetadata } & Pick<Pro
             <>
               <div>
                 {dotMetadata.modules.map((module) => (
-                  <p key={module.moduleName}>{module.moduleName}</p>
+                  <p key={module}>{module}</p>
                 ))}
               </div>
               <Button
@@ -156,11 +156,7 @@ const ModuleDotMetadataContent: FC<{ dotMetadata: DotModuleMetadata }> = ({ dotM
   const items: ComponentProps<typeof DefinitionList>['items'] = [
     {
       term: 'Module Name',
-      description: (
-        <Link to={path.modules.show(dotMetadata.modules.map((module) => module.moduleName))}>
-          {dotMetadata.modules.map((module) => module.moduleName).join(' / ')}
-        </Link>
-      ),
+      description: <Link to={path.modules.show(dotMetadata.modules)}>{dotMetadata.modules.join(' / ')}</Link>,
     },
   ]
 
diff --git a/frontend/components/SourceModulesComboBox/SourceModulesComboBox.tsx b/frontend/components/SourceModulesComboBox/SourceModulesComboBox.tsx
index 5bf7d87..47fc324 100644
--- a/frontend/components/SourceModulesComboBox/SourceModulesComboBox.tsx
+++ b/frontend/components/SourceModulesComboBox/SourceModulesComboBox.tsx
@@ -1,4 +1,4 @@
-import React, { FC, useCallback, useContext, useEffect, useMemo, useState } from 'react'
+import React, { FC, useCallback, useEffect, useMemo, useState } from 'react'
 
 import { Button, Cluster, ComboBoxItem, FaXmarkIcon, FormControl, SingleComboBox } from '@/components/ui'
 import { Module } from '@/models/module'
@@ -14,11 +14,11 @@ type Props = {
   onUpdate: (modules: Module[]) => void
 }
 
-const equalModules = (a: Module[], b: Module[]) => a.every((module, index) => module.moduleName === (b[index]?.moduleName ?? ''))
+const equalModules = (a: Module[], b: Module[]) => a.every((module, index) => module === (b[index] ?? ''))
 
 const convertModulesToItem = (modules: Module[]): Item => ({
-  label: modules.map((module) => module.moduleName).join(' / '),
-  value: modules.map((module) => module.moduleName).join('/'),
+  label: modules.join(' / '),
+  value: modules.join('/'),
   data: modules,
 })
 
@@ -56,7 +56,7 @@ export const SourceModulesComboBox: FC<Props> = ({ sourceName, initialModules, o
 
   const handleAddItem = useCallback(
     (label: string) => {
-      const temporaryModules: Module[] = label.split(DELIMITER_RE).map((moduleName) => ({ moduleName }))
+      const temporaryModules: Module[] = label.split(DELIMITER_RE)
       const newItem = convertModulesToItem(temporaryModules)
 
       setTemporaryItem(newItem)
diff --git a/frontend/components/UpdateSourceModulesButton/UpdateSourceModulesButton.tsx b/frontend/components/UpdateSourceModulesButton/UpdateSourceModulesButton.tsx
index 41b9224..d847117 100644
--- a/frontend/components/UpdateSourceModulesButton/UpdateSourceModulesButton.tsx
+++ b/frontend/components/UpdateSourceModulesButton/UpdateSourceModulesButton.tsx
@@ -32,7 +32,7 @@ export const UpdateSourceModulesButton: FC<Props> = ({ sourceName, newModules, o
   } else {
     return (
       <Button square={true} variant="primary" onClick={updateSourceModules} size="s">
-        <Tooltip message={`Save "${newModules.map((mod) => mod.moduleName).join('/')}"`} horizontal="center" vertical="bottom">
+        <Tooltip message={`Save "${newModules.join('/')}"`} horizontal="center" vertical="bottom">
           <FaCopyIcon />
         </Tooltip>
       </Button>
diff --git a/frontend/models/module.ts b/frontend/models/module.ts
index 640aed3..5e6ed7c 100644
--- a/frontend/models/module.ts
+++ b/frontend/models/module.ts
@@ -1,11 +1,7 @@
-export type Module = {
-  moduleName: string
-}
+export type Module = string
 
 export type SpecificModule = {
-  modules: Array<{
-    moduleName: string
-  }>
+  modules: Module[]
   sources: Array<{
     sourceName: string
     memo: string
diff --git a/frontend/models/source.ts b/frontend/models/source.ts
index 85e3de1..d3047e8 100644
--- a/frontend/models/source.ts
+++ b/frontend/models/source.ts
@@ -51,9 +51,7 @@ export const sortSources = (sources: Source[], key: 'sourceName' | 'modules', so
       break
     }
     case 'modules': {
-      sorted = sorted.sort((a, b) =>
-        ascString(a.modules.map((module) => module.moduleName).join('-'), b.modules.map((module) => module.moduleName).join('-')),
-      )
+      sorted = sorted.sort((a, b) => ascString(a.modules.join('---'), b.modules.join('---')))
     }
   }
 
diff --git a/frontend/pages/Modules/List.tsx b/frontend/pages/Modules/List.tsx
index 2b00808..eefd602 100644
--- a/frontend/pages/Modules/List.tsx
+++ b/frontend/pages/Modules/List.tsx
@@ -13,12 +13,11 @@ const ModuleRow: FC<{ modules: Module[] }> = ({ modules }) => (
   <Cluster>
     {modules.map((module, index) => {
       const current = modules.slice(0, index + 1)
-      const moduleNames: string[] = current.map((mod) => mod.moduleName)
 
       return (
         <Text key={index}>
           {index > 0 && ' / '}
-          <Link to={path.modules.show(moduleNames)}>{module.moduleName}</Link>
+          <Link to={path.modules.show(current)}>{module}</Link>
         </Text>
       )
     })}
diff --git a/frontend/pages/Sources/List.tsx b/frontend/pages/Sources/List.tsx
index 0f0f8b0..30ac067 100644
--- a/frontend/pages/Sources/List.tsx
+++ b/frontend/pages/Sources/List.tsx
@@ -97,9 +97,7 @@ const Row: FC<RowProps> = ({ source, recentModules, onUpdated, setRecentModules
             <div>
               {source.modules.map((module, index) => (
                 <Text key={index} as="div" whiteSpace="nowrap">
-                  <Link to={path.modules.show(source.modules.slice(0, index + 1).map((mod) => mod.moduleName))}>
-                    {module.moduleName}
-                  </Link>
+                  <Link to={path.modules.show(source.modules.slice(0, index + 1))}>{module}</Link>
                 </Text>
               ))}
             </div>
diff --git a/frontend/pages/Sources/Show.tsx b/frontend/pages/Sources/Show.tsx
index dbc246c..e2c3320 100644
--- a/frontend/pages/Sources/Show.tsx
+++ b/frontend/pages/Sources/Show.tsx
@@ -69,13 +69,9 @@ export const Show: React.FC = () => {
                       ) : (
                         <tbody>
                           {specificSource.modules.map((module, index) => (
-                            <tr key={module.moduleName}>
+                            <tr key={module}>
                               <Td>
-                                <Link
-                                  to={path.modules.show(specificSource.modules.slice(0, index + 1).map((mod) => mod.moduleName))}
-                                >
-                                  {module.moduleName}
-                                </Link>
+                                <Link to={path.modules.show(specificSource.modules.slice(0, index + 1))}>{module}</Link>
                               </Td>
                             </tr>
                           ))}
diff --git a/frontend/repositories/combinedDefinitionRepository.ts b/frontend/repositories/combinedDefinitionRepository.ts
index 27e6f4f..10ae2be 100644
--- a/frontend/repositories/combinedDefinitionRepository.ts
+++ b/frontend/repositories/combinedDefinitionRepository.ts
@@ -12,9 +12,7 @@ type DotSourceMetadataResponse = {
   type: 'source'
   memo: string
   source_name: string
-  modules: Array<{
-    module_name: string
-  }>
+  modules: string[]
 }
 
 type DotDependencyMetadataResponse = {
@@ -32,9 +30,7 @@ type DotDependencyMetadataResponse = {
 type DotModuleMetadataResponse = {
   id: string
   type: 'module'
-  modules: Array<{
-    module_name: string
-  }>
+  modules: string[]
 }
 
 type DotMetadataResponse = DotSourceMetadataResponse | DotDependencyMetadataResponse | DotModuleMetadataResponse
@@ -48,9 +44,7 @@ type CombinedDefinitionReponse = {
     source_name: string
     resolved_alias: string | null
     memo: string
-    modules: Array<{
-      module_name: string
-    }>
+    modules: string[]
   }>
 }
 
@@ -62,9 +56,7 @@ const parseDotMetadata = (metadata: DotMetadataResponse): DotMetadata => {
         type: metadata.type,
         sourceName: metadata.source_name,
         memo: metadata.memo,
-        modules: metadata.modules.map((module) => ({
-          moduleName: module.module_name,
-        })),
+        modules: metadata.modules,
       }
     }
     case 'dependency': {
@@ -85,9 +77,7 @@ const parseDotMetadata = (metadata: DotMetadataResponse): DotMetadata => {
       return {
         id: metadata.id,
         type: metadata.type,
-        modules: metadata.modules.map((module) => ({
-          moduleName: module.module_name,
-        })),
+        modules: metadata.modules,
       }
     }
   }
@@ -105,9 +95,7 @@ export const fetchCombinedDefinition = async (requestPath: string): Promise<Comb
       sourceName: source.source_name,
       resolvedAlias: source.resolved_alias,
       memo: source.memo,
-      modules: source.modules.map((module) => ({
-        moduleName: module.module_name,
-      })),
+      modules: source.modules,
     })),
   }
 }
diff --git a/frontend/repositories/moduleRepository.ts b/frontend/repositories/moduleRepository.ts
index ffd9ff1..1d413ee 100644
--- a/frontend/repositories/moduleRepository.ts
+++ b/frontend/repositories/moduleRepository.ts
@@ -6,22 +6,20 @@ import { Module, SpecificModule } from '@/models/module'
 import { get } from './httpRequest'
 
 type ModulesReponse = {
-  modules: Array<Array<{ module_name: string }>>
+  modules: string[][]
 }
 
 export const useModules = () => {
   const { data, isLoading, mutate } = useSWR<Module[][]>(path.api.modules.index(), async () => {
     const response = await get<ModulesReponse>(path.api.modules.index())
-    return response.modules.map((moduleList) => moduleList.map((module) => ({ moduleName: module.module_name })))
+    return response.modules
   })
 
   return { data, isLoading, mutate }
 }
 
 type SpecificModuleResponse = {
-  modules: Array<{
-    module_name: string
-  }>
+  modules: string[]
   related_definitions: Array<{
     id: number
     title: string
@@ -37,9 +35,7 @@ export const useModule = (moduleNames: string[]) => {
     const response = await get<SpecificModuleResponse>(path.api.modules.show(moduleNames))
 
     return {
-      modules: response.modules.map((mod) => ({
-        moduleName: mod.module_name,
-      })),
+      modules: response.modules,
       sources: response.sources.map((source) => ({
         sourceName: source.source_name,
         memo: source.memo,
diff --git a/frontend/repositories/sourceModulesRepository.ts b/frontend/repositories/sourceModulesRepository.ts
index 7cec5d4..ad5c295 100644
--- a/frontend/repositories/sourceModulesRepository.ts
+++ b/frontend/repositories/sourceModulesRepository.ts
@@ -7,10 +7,9 @@ import { post } from './httpRequest'
 
 const updateModules = async (url: string, { arg }: { arg: { modules: Module[] } }) => {
   const { modules } = arg
-  const moduleNames = modules.map((mod) => mod.moduleName)
 
   await post(url, {
-    modules: moduleNames,
+    modules,
   })
 }
 
diff --git a/frontend/repositories/sourceRepository.ts b/frontend/repositories/sourceRepository.ts
index 34bd3df..7883944 100644
--- a/frontend/repositories/sourceRepository.ts
+++ b/frontend/repositories/sourceRepository.ts
@@ -10,9 +10,7 @@ type SourcesReponse = {
     source_name: string
     resolved_alias: string | null
     memo: string
-    modules: Array<{
-      module_name: string
-    }>
+    modules: string[]
   }>
   classified_sources_count: number
 }
@@ -25,7 +23,7 @@ export const useSources = () => {
         sourceName: source.source_name,
         resolvedAlias: source.resolved_alias,
         memo: source.memo,
-        modules: source.modules.map((module) => ({ moduleName: module.module_name })),
+        modules: source.modules,
       })),
       classifiedSourcesCount: response.classified_sources_count,
     }
@@ -38,9 +36,7 @@ type SpecificSourceResponse = {
   source_name: string
   resolved_alias: string | null
   memo: string
-  modules: Array<{
-    module_name: string
-  }>
+  modules: string[]
   related_definitions: Array<{
     id: number
     title: string
@@ -63,7 +59,7 @@ export const useSource = (sourceName: string) => {
       sourceName: response.source_name,
       resolvedAlias: response.resolved_alias,
       memo: response.memo,
-      modules: response.modules.map((module) => ({ moduleName: module.module_name })),
+      modules: response.modules,
       relatedDefinitions: response.related_definitions.map((definition) => ({ id: definition.id, title: definition.title })),
       reverseDependencies: response.reverse_dependencies.map((dependency) => ({
         sourceName: dependency.source_name,
diff --git a/lib/diver_down/web.rb b/lib/diver_down/web.rb
index 56bec4a..71e1577 100644
--- a/lib/diver_down/web.rb
+++ b/lib/diver_down/web.rb
@@ -109,20 +109,24 @@ def call(env)
 
     def load_definition_files_on_thread(definition_files)
       definition_loader = DiverDown::Web::DefinitionLoader.new
+      store = self.class.store
 
       Thread.new do
         loop do
           break if definition_files.empty?
 
+          # If store is changed in test, stop loading.
+          break if store != self.class.store
+
           definition_file = definition_files.shift
           definition = definition_loader.load_file(definition_file)
 
           # No needed to synchronize because this is executed on a single thread.
-          self.class.store.set(definition)
+          store.set(definition)
         end
 
         # Cache combined_definition
-        self.class.store.combined_definition
+        store.combined_definition
       end
     end
   end
diff --git a/lib/diver_down/web/action.rb b/lib/diver_down/web/action.rb
index 9f34207..6c8f7ed 100644
--- a/lib/diver_down/web/action.rb
+++ b/lib/diver_down/web/action.rb
@@ -79,9 +79,7 @@ def sources
               source_name:,
               resolved_alias: @metadata.source_alias.resolve_alias(source_name),
               memo: source_metadata.memo,
-              modules: source_metadata.modules.map do |module_name|
-                { module_name: }
-              end,
+              modules: source_metadata.modules,
             }
           end,
           classified_sources_count:
@@ -103,13 +101,7 @@ def modules
         # rubocop:enable Style/HashEachMethods
 
         json(
-          modules: module_set.sort.map do
-            _1.map do |module_name|
-              {
-                module_name:,
-              }
-            end
-          end
+          modules: module_set.sort
         )
       end
 
@@ -140,11 +132,7 @@ def module(module_names)
         related_definitions = related_definition_store_ids.map { @store.get(_1) }
 
         json(
-          modules: module_names.map do
-            {
-              module_name: _1,
-            }
-          end,
+          modules: module_names,
           sources: source_names.sort.map do |source_name|
             {
               source_name:,
@@ -315,9 +303,7 @@ def source(source_name)
           source_name:,
           resolved_alias: @metadata.source_alias.resolve_alias(source_name),
           memo: @metadata.source(source_name).memo,
-          modules: module_names.map do
-            { module_name: _1 }
-          end,
+          modules: module_names,
           related_definitions: related_definitions.map do |id, definition|
             {
               id:,
@@ -451,9 +437,7 @@ def render_combined_definition(ids, definition, titles, compound:, concentrate:,
               source_name: _1.source_name,
               resolved_alias: @metadata.source_alias.resolve_alias(_1.source_name),
               memo: @metadata.source(_1.source_name).memo,
-              modules: @metadata.source(_1.source_name).modules.map do |module_name|
-                { module_name: }
-              end,
+              modules: @metadata.source(_1.source_name).modules,
             }
           end
         )
diff --git a/lib/diver_down/web/definition_to_dot.rb b/lib/diver_down/web/definition_to_dot.rb
index b79b237..809af40 100644
--- a/lib/diver_down/web/definition_to_dot.rb
+++ b/lib/diver_down/web/definition_to_dot.rb
@@ -31,11 +31,7 @@ def to_h
           private
 
           def source_to_h
-            modules = metadata.source(data.source_name).modules.map do
-              {
-                module_name: _1,
-              }
-            end
+            modules = metadata.source(data.source_name).modules
 
             {
               id:,
@@ -68,11 +64,7 @@ def module_to_h
             {
               id:,
               type: 'module',
-              modules: data.map do
-                {
-                  module_name: _1,
-                }
-              end,
+              modules: data,
             }
           end
         end
diff --git a/spec/diver_down/web/definition_to_dot_spec.rb b/spec/diver_down/web/definition_to_dot_spec.rb
index 09b0571..429a9b8 100644
--- a/spec/diver_down/web/definition_to_dot_spec.rb
+++ b/spec/diver_down/web/definition_to_dot_spec.rb
@@ -167,30 +167,17 @@ def build_definition(title: 'title', sources: [])
               {
                 id: 'graph_1',
                 type: 'module',
-                modules: [
-                  {
-                    module_name: 'A',
-                  },
-                ],
+                modules: ['A'],
               }, {
                 id: 'graph_2',
                 type: 'module',
-                modules: [
-                  {
-                    module_name: 'A',
-                  }, {
-                    module_name: 'B',
-                  },
-                ],
+                modules: ['A', 'B'],
               }, {
                 id: 'graph_3',
                 type: 'source',
                 source_name: 'a.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'A' },
-                  { module_name: 'B' },
-                ],
+                modules: ['A', 'B'],
               },
             ]
           )
@@ -334,43 +321,29 @@ def build_definition(title: 'title', sources: [])
               {
                 id: 'graph_1',
                 type: 'module',
-                modules: [
-                  {
-                    module_name: 'A',
-                  },
-                ],
+                modules: ['A'],
               }, {
                 id: 'graph_2',
                 type: 'source',
                 source_name: 'a.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'A' },
-                ],
+                modules: ['A'],
               }, {
                 id: 'graph_3',
                 type: 'module',
-                modules: [
-                  {
-                    module_name: 'B',
-                  },
-                ],
+                modules: ['B'],
               }, {
                 id: 'graph_4',
                 type: 'source',
                 source_name: 'b.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'B' },
-                ],
+                modules: ['B'],
               }, {
                 id: 'graph_5',
                 type: 'source',
                 source_name: 'c.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'B' },
-                ],
+                modules: ['B'],
               }, {
                 id: 'graph_6',
                 type: 'dependency',
@@ -450,43 +423,29 @@ def build_definition(title: 'title', sources: [])
               {
                 id: 'graph_1',
                 type: 'module',
-                modules: [
-                  {
-                    module_name: 'A',
-                  },
-                ],
+                modules: ['A'],
               }, {
                 id: 'graph_2',
                 type: 'source',
                 source_name: 'a.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'A' },
-                ],
+                modules: ['A'],
               }, {
                 id: 'graph_3',
                 type: 'module',
-                modules: [
-                  {
-                    module_name: 'B',
-                  },
-                ],
+                modules: ['B'],
               }, {
                 id: 'graph_4',
                 type: 'source',
                 source_name: 'b.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'B' },
-                ],
+                modules: ['B'],
               }, {
                 id: 'graph_5',
                 type: 'source',
                 source_name: 'c.rb',
                 memo: '',
-                modules: [
-                  { module_name: 'B' },
-                ],
+                modules: ['B'],
               }, {
                 id: 'graph_6',
                 type: 'dependency',
@@ -591,9 +550,9 @@ def build_definition(title: 'title', sources: [])
 
           expect(instance.dot_metadata).to eq(
             [
-              { id: 'graph_1', type: 'module', modules: [{ module_name: 'A' }] },
-              { id: 'graph_2', type: 'module', modules: [{ module_name: 'B' }] },
-              { id: 'graph_3', type: 'module', modules: [{ module_name: 'B' }, { module_name: 'C' }] },
+              { id: 'graph_1', type: 'module', modules: ['A'] },
+              { id: 'graph_2', type: 'module', modules: ['B'] },
+              { id: 'graph_3', type: 'module', modules: ['B', 'C'] },
               {
                 id: 'graph_4',
                 type: 'dependency',
@@ -695,12 +654,12 @@ def build_definition(title: 'title', sources: [])
           expect(instance.dot_metadata).to eq(
             [
               { id: 'graph_1', type: 'source', source_name: 'a.rb', memo: '', modules: [] },
-              { id: 'graph_2', type: 'module', modules: [{ module_name: 'A' }] },
-              { id: 'graph_3', type: 'source', source_name: 'b.rb', memo: '', modules: [{ module_name: 'A' }] },
-              { id: 'graph_4', type: 'module', modules: [{ module_name: 'A' }, { module_name: 'C' }] },
-              { id: 'graph_5', type: 'source', source_name: 'c.rb', memo: '', modules: [{ module_name: 'A' }, { module_name: 'C' }] },
-              { id: 'graph_6', type: 'module', modules: [{ module_name: 'B' }] },
-              { id: 'graph_7', type: 'source', source_name: 'd.rb', memo: '', modules: [{ module_name: 'B' }] },
+              { id: 'graph_2', type: 'module', modules: ['A'] },
+              { id: 'graph_3', type: 'source', source_name: 'b.rb', memo: '', modules: ['A'] },
+              { id: 'graph_4', type: 'module', modules: ['A', 'C'] },
+              { id: 'graph_5', type: 'source', source_name: 'c.rb', memo: '', modules: ['A', 'C'] },
+              { id: 'graph_6', type: 'module', modules: ['B'] },
+              { id: 'graph_7', type: 'source', source_name: 'd.rb', memo: '', modules: ['B'] },
             ]
           )
         end
diff --git a/spec/diver_down/web_spec.rb b/spec/diver_down/web_spec.rb
index daeb847..1919b61 100644
--- a/spec/diver_down/web_spec.rb
+++ b/spec/diver_down/web_spec.rb
@@ -333,7 +333,7 @@ def assert_definition_group(definition_group, expected_ids)
             'source_name' => 'a.rb',
             'resolved_alias' => 'b.rb',
             'memo' => 'memo',
-            'modules' => [{ 'module_name' => 'A' }],
+            'modules' => ['A'],
           },
           {
             'source_name' => 'b.rb',
@@ -387,19 +387,8 @@ def assert_definition_group(definition_group, expected_ids)
       expect(last_response.status).to eq(200)
       expect(JSON.parse(last_response.body)).to eq({
         'modules' => [
-          [
-            {
-              'module_name' => 'A',
-            }, {
-              'module_name' => 'B',
-            },
-          ], [
-            {
-              'module_name' => 'B',
-            }, {
-              'module_name' => 'C',
-            },
-          ],
+          ['A', 'B'],
+          ['B', 'C'],
         ],
       })
     end
@@ -439,11 +428,7 @@ def assert_definition_group(definition_group, expected_ids)
 
       expect(last_response.status).to eq(200)
       expect(JSON.parse(last_response.body)).to eq({
-        'modules' => [
-          {
-            'module_name' => 'A',
-          },
-        ],
+        'modules' => ['A'],
         'sources' => [
           {
             'source_name' => 'a.rb',
@@ -470,13 +455,7 @@ def assert_definition_group(definition_group, expected_ids)
 
       expect(last_response.status).to eq(200)
       expect(JSON.parse(last_response.body)).to eq({
-        'modules' => [
-          {
-            'module_name' => 'A',
-          }, {
-            'module_name' => 'B',
-          },
-        ],
+        'modules' => ['A', 'B'],
         'sources' => [
           {
             'source_name' => 'b.rb',
@@ -510,11 +489,7 @@ def assert_definition_group(definition_group, expected_ids)
 
       expect(last_response.status).to eq(200)
       expect(JSON.parse(last_response.body)).to eq({
-        'modules' => [
-          {
-            'module_name' => 'グローバル',
-          },
-        ],
+        'modules' => ['グローバル'],
         'sources' => [
           {
             'source_name' => 'a.rb',