fix issues in tests flagged by LGTM (#5150)

test/mocha/comments.js

@@ -191,7 +191,7 @@ describe("comments", function() {
     });
 
     it("Should correctly preserve new lines around comments", function() {
-        var tests = [
+        [
             [
                 "// foo",
                 "// bar",

test/mocha/glob.js

@@ -1,7 +1,6 @@
 var assert = require("assert");
 var exec = require("child_process").exec;
 var path = require("path");
-var readFileSync = require("fs").readFileSync;
 
 describe("bin/uglifyjs with input file globs", function() {
     var uglifyjscmd = '"' + process.argv[0] + '" bin/uglifyjs';

test/mocha/minify.js

@@ -25,7 +25,7 @@ describe("minify", function() {
         if (result.error) throw result.error;
         assert.strictEqual(result.code, "print(42);");
         assert.strictEqual(JSON.stringify(options), value);
-    })
+    });
     it("Should skip inherited keys from `files`", function() {
         var files = Object.create({ skip: this });
         files[0] = "alert(1 + 1)";

test/mocha/reduce.js

@@ -1,5 +1,4 @@
 var assert = require("assert");
-var exec = require("child_process").exec;
 var fs = require("fs");
 var reduce_test = require("../reduce");
 var semver = require("semver");

test/mocha/sourcemaps.js

@@ -362,7 +362,7 @@ describe("sourcemaps", function() {
         it("Should not modify input source map", function() {
             var orig = get_map();
             var original = JSON.stringify(orig);
-            var map = prepare_map(orig);
+            prepare_map(orig);
             assert.strictEqual(JSON.stringify(orig), original);
         });
         it("Should copy over original sourcesContent", function() {

test/mocha/string-literal.js

@@ -12,7 +12,7 @@ describe("String literals", function() {
             '"\u2029"',
         ].forEach(function(input) {
             assert.throws(function() {
-                var ast = UglifyJS.parse(input);
+                UglifyJS.parse(input);
             }, function(e) {
                 return e instanceof UglifyJS.JS_Parse_Error
                     && e.message === "Unterminated string constant";
@@ -44,7 +44,7 @@ describe("String literals", function() {
             '"use strict";\n"\\011"',
         ].forEach(function(input) {
             assert.throws(function() {
-                var output = UglifyJS.parse(input);
+                UglifyJS.parse(input);
             }, function(e) {
                 return e instanceof UglifyJS.JS_Parse_Error
                     && e.message === "Legacy octal escape sequences are not allowed in strict mode";