diff --git a/test/cases/asset-modules/test.filter.js b/test/cases/asset-modules/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/asset-modules/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/chunkFilename-as-function/webpack.config.js b/test/cases/chunkFilename-as-function/webpack.config.js
index 38450896..6a4fee5b 100644
--- a/test/cases/chunkFilename-as-function/webpack.config.js
+++ b/test/cases/chunkFilename-as-function/webpack.config.js
@@ -1,5 +1,3 @@
-import { version as webpackVersion } from 'webpack';
-
 import Self from '../../../src';
 
 module.exports = {
@@ -15,10 +13,7 @@ module.exports = {
   plugins: [
     new Self({
       filename: '[name].css',
-      chunkFilename:
-        webpackVersion[0] === '4'
-          ? '[id].[name].css'
-          : ({ chunk }) => `${chunk.id}.${chunk.name}.css`,
+      chunkFilename: ({ chunk }) => `${chunk.id}.${chunk.name}.css`,
     }),
   ],
 };
diff --git a/test/cases/chunkFilename-fullhash/test.filter.js b/test/cases/chunkFilename-fullhash/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/chunkFilename-fullhash/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/content-entries-with-same-import/test.filter.js b/test/cases/content-entries-with-same-import/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/content-entries-with-same-import/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/dependOn-multiple-files-per-entry/test.filter.js b/test/cases/dependOn-multiple-files-per-entry/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/dependOn-multiple-files-per-entry/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/dependOn/test.filter.js b/test/cases/dependOn/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/dependOn/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/es-named-export-output-module/test.filter.js b/test/cases/es-named-export-output-module/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/es-named-export-output-module/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/output-iife/test.filter.js b/test/cases/output-iife/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/output-iife/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/output-module/test.filter.js b/test/cases/output-module/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/output-module/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/simple-css-modules-mode-local-output-module/test.filter.js b/test/cases/simple-css-modules-mode-local-output-module/test.filter.js
deleted file mode 100644
index 042a0256..00000000
--- a/test/cases/simple-css-modules-mode-local-output-module/test.filter.js
+++ /dev/null
@@ -1,3 +0,0 @@
-const webpack = require('webpack');
-
-module.exports = () => webpack.version[0] !== '4';
diff --git a/test/cases/split-chunks-recursiveIssuer/webpack.config.js b/test/cases/split-chunks-recursiveIssuer/webpack.config.js
index 205f9be5..d94301fb 100644
--- a/test/cases/split-chunks-recursiveIssuer/webpack.config.js
+++ b/test/cases/split-chunks-recursiveIssuer/webpack.config.js
@@ -1,18 +1,13 @@
-import { version as webpackVersion } from 'webpack';
-
 import Self from '../../../src';
 
 function recursiveIssuer(m, c) {
-  const issuer =
-    webpackVersion[0] === '4' ? m.issuer : c.moduleGraph.getIssuer(m);
+  const issuer = c.moduleGraph.getIssuer(m);
 
   if (issuer) {
     return recursiveIssuer(issuer, c);
   }
 
-  const chunks =
-    // eslint-disable-next-line no-underscore-dangle
-    webpackVersion[0] === '4' ? m._chunks : c.chunkGraph.getModuleChunks(m);
+  const chunks = c.chunkGraph.getModuleChunks(m);
 
   for (const chunk of chunks) {
     return chunk.name;