fix: Fix snake casing numbers. (#1052)

Fixes #1048

src/case.ts

@@ -1,4 +1,4 @@
-import { camelCase as camelCaseAnything, snakeCase as snakeCaseAnything } from "case-anything";
+import { camelCase as camelCaseAnything } from "case-anything";
 
 import { Options } from "./options";
 
@@ -24,7 +24,14 @@ export function snakeToCamel(s: string): string {
 }
 
 export function camelToSnake(s: string): string {
-  return snakeCaseAnything(s).toUpperCase();
+  return (
+    s
+      // any number or little-char -> big char
+      .replace(/[a-z0-9]([A-Z])/g, (m) => m[0] + "_" + m[1])
+      // any multiple big char -> next word
+      .replace(/[A-Z]([A-Z][a-z])/g, (m) => m[0] + "_" + m.substring(1))
+      .toUpperCase()
+  );
 }
 
 export function capitalize(s: string): string {

tests/case-test.ts

@@ -59,6 +59,10 @@ describe("case", () => {
     expect(camelToSnake("getAPIValue")).toEqual("GET_API_VALUE");
   });
 
+  it("converts string to snake case respecting number separation, getV1Foo === GET_V1_FOO", () => {
+    expect(camelToSnake("getV1Foo")).toEqual("GET_V1_FOO");
+  });
+
   describe("getFieldJsonName", () => {
     it("keeps snake case when jsonName is probably not set", () => {
       expect(getFieldJsonName({ name: "foo_bar", jsonName: "fooBar" }, { snakeToCamel: [], useJsonName: false })).toBe(