Add support for Config module, closes #2346 (#2816)

.changeset/hungry-eyes-doubt.md

@@ -0,0 +1,5 @@
+---
+"@effect/schema": patch
+---
+
+Add support for `Config` module, closes #2346

packages/schema/src/Schema.ts

@@ -9,6 +9,8 @@ import * as boolean_ from "effect/Boolean"
 import type { Brand } from "effect/Brand"
 import * as cause_ from "effect/Cause"
 import * as chunk_ from "effect/Chunk"
+import * as config_ from "effect/Config"
+import * as configError_ from "effect/ConfigError"
 import * as data_ from "effect/Data"
 import * as duration_ from "effect/Duration"
 import * as Effect from "effect/Effect"
@@ -47,6 +49,7 @@ import * as util_ from "./internal/util.js"
 import * as ParseResult from "./ParseResult.js"
 import * as pretty_ from "./Pretty.js"
 import type * as Serializable from "./Serializable.js"
+import * as TreeFormatter from "./TreeFormatter.js"
 
 /**
  * @since 1.0.0
@@ -8056,3 +8059,18 @@ export class BooleanFromUnknown extends transform(
   static override annotations: (annotations: Annotations.Schema<boolean>) => typeof BooleanFromUnknown = super
     .annotations
 }
+
+/**
+ * @category Config validations
+ * @since 1.0.0
+ */
+export const Config = <A>(name: string, schema: Schema<A, string>): config_.Config<A> => {
+  const decodeEither_ = decodeEither(schema)
+  return config_.string(name).pipe(
+    config_.mapOrFail((a) =>
+      decodeEither_(a).pipe(
+        either_.mapLeft((error) => configError_.InvalidData([], TreeFormatter.formatErrorSync(error)))
+      )
+    )
+  )
+}

packages/schema/test/Schema/Config/Config.test.ts

@@ -0,0 +1,59 @@
+import * as Schema from "@effect/schema/Schema"
+import type * as Config from "effect/Config"
+import * as ConfigError from "effect/ConfigError"
+import * as ConfigProvider from "effect/ConfigProvider"
+import * as Effect from "effect/Effect"
+import * as Exit from "effect/Exit"
+import { describe, expect, it } from "vitest"
+
+/**
+ * Asserts that loading a configuration with invalid data fails with the expected error.
+ *
+ * @param config - The configuration to load.
+ * @param map - The map of configuration values.
+ * @param error - The expected error.
+ */
+const assertFailure = <A>(
+  config: Config.Config<A>,
+  map: ReadonlyArray<readonly [string, string]>,
+  error: ConfigError.ConfigError
+) => {
+  const configProvider = ConfigProvider.fromMap(new Map(map))
+  const result = Effect.runSync(Effect.exit(configProvider.load(config)))
+  expect(result).toStrictEqual(Exit.fail(error))
+}
+
+/**
+ * Asserts that loading a configuration with valid data succeeds and returns the expected value.
+ *
+ * @param config - The configuration to load.
+ * @param map - The map of configuration values.
+ * @param a - The expected value.
+ */
+const assertSuccess = <A>(
+  config: Config.Config<A>,
+  map: ReadonlyArray<readonly [string, string]>,
+  a: A
+) => {
+  const configProvider = ConfigProvider.fromMap(new Map(map))
+  const result = Effect.runSync(Effect.exit(configProvider.load(config)))
+  expect(result).toStrictEqual(Exit.succeed(a))
+}
+
+describe("Config", () => {
+  it("should validate the configuration schema correctly", () => {
+    const config = Schema.Config("A", Schema.NonEmpty)
+    assertSuccess(config, [["A", "a"]], "a")
+    assertFailure(config, [], ConfigError.MissingData(["A"], `Expected A to exist in the provided map`))
+    assertFailure(
+      config,
+      [["A", ""]],
+      ConfigError.InvalidData(
+        ["A"],
+        `NonEmpty
+└─ Predicate refinement failure
+   └─ Expected NonEmpty (a non empty string), actual ""`
+      )
+    )
+  })
+})