Increase range threshold in regexp/prefer-range (#360)

* Increase range threshold in `regexp/prefer-range`

* Updated documentation

Author: RunDevelopment

docs/rules/prefer-range.md

@@ -22,11 +22,11 @@ This rule is aimed to use ranges instead of multiple adjacent characters in char
 /* eslint regexp/prefer-range: "error" */
 
 /* ✓ GOOD */
-var foo = /[a-c]/
+var foo = /[0-9]/
 var foo = /[a-f]/
 
 /* ✗ BAD */
-var foo = /[abc]/
+var foo = /[123456]/
 var foo = /[a-cd-f]/
 ```
 
@@ -58,15 +58,15 @@ It allows all values that the [allowedCharacterRanges] setting allows.
 /* eslint regexp/prefer-range: ["error", { "target": "alphanumeric" }] */
 
 /* ✓ GOOD */
-var foo = /[a-c]/
+var foo = /[0-9]/
 var foo = /[a-f]/
 var foo = /[!-$]/
 var foo = /[!"#$]/
 var foo = /[😀-😄]/u
 var foo = /[😀😁😂😃😄]/u
 
 /* ✗ BAD */
-var foo = /[abc]/
+var foo = /[123456]/
 var foo = /[a-cd-f]/
 ```
 
@@ -80,13 +80,13 @@ var foo = /[a-cd-f]/
 /* eslint regexp/prefer-range: ["error", { "target": "all" }] */
 
 /* ✓ GOOD */
-var foo = /[a-c]/
+var foo = /[0-9]/
 var foo = /[a-f]/
 var foo = /[!-$]/
 var foo = /[😀-😄]/u
 
 /* ✗ BAD */
-var foo = /[abc]/
+var foo = /[123456]/
 var foo = /[a-cd-f]/
 var foo = /[!"#$]/
 var foo = /[😀😁😂😃😄]/u
@@ -102,14 +102,14 @@ var foo = /[😀😁😂😃😄]/u
 /* eslint regexp/prefer-range: ["error", { "target": [ "alphanumeric", "😀-😏" ] }] */
 
 /* ✓ GOOD */
-var foo = /[a-c]/
+var foo = /[0-9]/
 var foo = /[a-f]/
 var foo = /[!-$]/
 var foo = /[!"#$]/
 var foo = /[😀-😄]/u
 
 /* ✗ BAD */
-var foo = /[abc]/
+var foo = /[123456]/
 var foo = /[a-cd-f]/
 var foo = /[😀😁😂😃😄]/u
 ```

lib/rules/prefer-range.ts

@@ -148,10 +148,8 @@ export default createRule("prefer-range", {
                     }
 
                     for (const group of groups) {
-                        if (
-                            group.max.value - group.min.value > 1 &&
-                            group.nodes.length > 1
-                        ) {
+                        const charCount = group.max.value - group.min.value + 1
+                        if (charCount >= 4 && group.nodes.length > 1) {
                             const newText = `${group.min.raw}-${group.max.raw}`
                             const ranges = getReportRanges(group.nodes)
                             if (!ranges) {

tests/lib/rules/prefer-range.ts

@@ -12,8 +12,10 @@ tester.run("prefer-range", rule as any, {
     valid: [
         `/[a]/`,
         `/[ab]/`,
-        `/[a-c]/`,
+        `/[abc]/`,
         `/[a-b]/`,
+        `/[a-c]/`,
+        `/[a-d]/`,
         `/[0-9]/`,
         `/[A-Z]/`,
         `/[a-zA-ZZ-a]/`,
@@ -59,25 +61,25 @@ tester.run("prefer-range", rule as any, {
     ],
     invalid: [
         {
-            code: `/[abc]/`,
-            output: `/[a-c]/`,
+            code: `/[abcd]/`,
+            output: `/[a-d]/`,
             errors: [
                 {
                     message:
-                        "Unexpected multiple adjacent characters. Use 'a-c' instead.",
+                        "Unexpected multiple adjacent characters. Use 'a-d' instead.",
                     line: 1,
                     column: 3,
                     endLine: 1,
-                    endColumn: 6,
+                    endColumn: 7,
                 },
             ],
         },
         {
-            code: `/[ABC abc]/`,
-            output: `/[A-C a-c]/`,
+            code: `/[ABCD abcd]/`,
+            output: `/[A-D a-d]/`,
             errors: [
-                "Unexpected multiple adjacent characters. Use 'A-C' instead.",
-                "Unexpected multiple adjacent characters. Use 'a-c' instead.",
+                "Unexpected multiple adjacent characters. Use 'A-D' instead.",
+                "Unexpected multiple adjacent characters. Use 'a-d' instead.",
             ],
         },
         {