[improvement] Generate more lenient enums (#170)

* [improvement] Generate more lenient enums

* Remove commented out code

* Add generated changelog entries

* 'value as value' in order to make type inference better

* Remove test directory

* Revert build.gradle changes

Co-authored-by: Patrick Szmucer <pszmucer@palantir.com>
Co-authored-by: svc-changelog <svc-changelog@palantir.com>

Author: 3 people

changelog/@unreleased/pr-170.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Generate more lenient enums.
+  links:
+  - https://github.com/palantir/conjure-typescript/pull/170

src/commands/generate/__tests__/resources/test-cases/ete-service/product/simpleEnum.ts

@@ -1,3 +1,7 @@
-export enum SimpleEnum {
-    VALUE = "VALUE"
+export namespace SimpleEnum {
+    export type VALUE = "VALUE";
+
+    export const VALUE = "VALUE" as "VALUE";
 }
+
+export type SimpleEnum = keyof typeof SimpleEnum;

src/commands/generate/__tests__/resources/test-cases/example-types/product/deprecatedEnumExample.ts

@@ -1,20 +1,27 @@
-export enum DeprecatedEnumExample {
-    ONE = "ONE",
+export namespace DeprecatedEnumExample {
+    export type ONE = "ONE";
     /**
      * @deprecated use ONE
      */
-    OLD_ONE = "OLD_ONE",
+    export type OLD_ONE = "OLD_ONE";
     /**
      * You should no longer use this
      * 
      * @deprecated use ONE
      */
-    OLD_DEPRECATED_ONE = "OLD_DEPRECATED_ONE",
+    export type OLD_DEPRECATED_ONE = "OLD_DEPRECATED_ONE";
     /**
      * You should no longer use this
      * 
      * @deprecated should use ONE
      * 
      */
-    OLD_DOCUMENTED_ONE = "OLD_DOCUMENTED_ONE"
+    export type OLD_DOCUMENTED_ONE = "OLD_DOCUMENTED_ONE";
+
+    export const ONE = "ONE" as "ONE";
+    export const OLD_ONE = "OLD_ONE" as "OLD_ONE";
+    export const OLD_DEPRECATED_ONE = "OLD_DEPRECATED_ONE" as "OLD_DEPRECATED_ONE";
+    export const OLD_DOCUMENTED_ONE = "OLD_DOCUMENTED_ONE" as "OLD_DOCUMENTED_ONE";
 }
+
+export type DeprecatedEnumExample = keyof typeof DeprecatedEnumExample;

src/commands/generate/__tests__/resources/test-cases/example-types/product/enumExample.ts

@@ -2,11 +2,17 @@
  * This enumerates the numbers 1:2 also 100.
  * 
  */
-export enum EnumExample {
-    ONE = "ONE",
-    TWO = "TWO",
+export namespace EnumExample {
+    export type ONE = "ONE";
+    export type TWO = "TWO";
     /**
      * Value of 100.
      */
-    ONE_HUNDRED = "ONE_HUNDRED"
+    export type ONE_HUNDRED = "ONE_HUNDRED";
+
+    export const ONE = "ONE" as "ONE";
+    export const TWO = "TWO" as "TWO";
+    export const ONE_HUNDRED = "ONE_HUNDRED" as "ONE_HUNDRED";
 }
+
+export type EnumExample = keyof typeof EnumExample;

src/commands/generate/__tests__/resources/test-cases/example-types/product/simpleEnum.ts

@@ -1,3 +1,7 @@
-export enum SimpleEnum {
-    VALUE = "VALUE"
+export namespace SimpleEnum {
+    export type VALUE = "VALUE";
+
+    export const VALUE = "VALUE" as "VALUE";
 }
+
+export type SimpleEnum = keyof typeof SimpleEnum;

src/commands/generate/__tests__/resources/types/enumExample.ts

@@ -1,4 +1,9 @@
-export enum EnumExample {
-    ONE = "ONE",
-    TWO = "TWO"
+export namespace EnumExample {
+    export type ONE = "ONE";
+    export type TWO = "TWO";
+
+    export const ONE = "ONE" as "ONE";
+    export const TWO = "TWO" as "TWO";
 }
+
+export type EnumExample = keyof typeof EnumExample;

src/commands/generate/__tests__/resources/types/enumWithDocs.ts

@@ -1,10 +1,15 @@
 /**
  * Some documentation
  */
-export enum EnumWithDocs {
+export namespace EnumWithDocs {
     /**
      * Some field documentation
      */
-    FOO = "FOO",
-    BAR = "BAR"
+    export type FOO = "FOO";
+    export type BAR = "BAR";
+
+    export const FOO = "FOO" as "FOO";
+    export const BAR = "BAR" as "BAR";
 }
+
+export type EnumWithDocs = keyof typeof EnumWithDocs;

src/commands/generate/typeGenerator.ts

@@ -50,22 +50,46 @@ export function generateType(
 /**
  * Generates a file of the following format:
  * ```
- * export type EnumExample = "ONE" | "TWO";
- * export const EnumExample = { ONE: "ONE" as "ONE", TWO: "TWO" as "TWO" };
+ * export namespace EnumExample {
+ *     export type ONE = "ONE";
+ *     export type TWO = "TWO";
+ *
+ *     export const ONE = "ONE" as "ONE";
+ *     export const TWO = "TWO" as "TWO";
+ * }
+ * export type EnumExample = keyof typeof EnumExample;
  * ```
+ *
+ * We do not use TypeScript Enums because they can not be assigned to an equivalent enum, making interop across
+ * libraries more difficult
  */
 export async function generateEnum(definition: IEnumDefinition, simpleAst: SimpleAst): Promise<void> {
     const sourceFile = simpleAst.createSourceFile(definition.typeName);
 
-    sourceFile.addEnum({
-        docs: definition.docs != null ? [{ description: definition.docs }] : undefined,
+    const namespaceDefinition = sourceFile.addNamespace({
         isExported: true,
-        members: definition.values.map(enumValue => ({
-            docs: addDeprecatedToDocs(enumValue),
+        name: definition.typeName.name,
+        typeAliases: definition.values.map(enumValue => ({
+            isExported: true,
             name: enumValue.value,
-            value: enumValue.value,
+            type: doubleQuote(enumValue.value),
+            docs: addDeprecatedToDocs(enumValue),
         })),
+        bodyText: writer => {
+            definition.values.forEach(({ value }) => {
+                const quotedValue = doubleQuote(value);
+                writer.writeLine(`export const ${value} = ${quotedValue} as ${quotedValue};`);
+            });
+        },
+    });
+    if (definition.docs != null) {
+        namespaceDefinition.addJsDoc(definition.docs);
+    }
+
+    sourceFile.addTypeAlias({
+        isExported: true,
         name: definition.typeName.name,
+        type: `keyof typeof ${definition.typeName.name}`,
     });
 
     sourceFile.formatText();