[Feature] - Adding and Removing Values

Package.resolved

@@ -6,8 +6,8 @@
         "repositoryURL": "https://github.com/apple/swift-collections.git",
         "state": {
           "branch": null,
-          "revision": "2d33a0ea89c961dcb2b3da2157963d9c0370347e",
-          "version": "1.0.1"
+          "revision": "48254824bb4248676bf7ce56014ff57b142b77eb",
+          "version": "1.0.2"
         }
       }
     ]

Sources/Dotenv.swift

@@ -49,6 +49,7 @@ public struct Dotenv {
     }
 
     /// Save an environment object to a file.
+    /// - Important: This method does not serialize process values to disk.
     /// - Parameters:
     ///   - environment: Environment to serialize.
     ///   - path: Path to save the environment to.

Sources/Environment.swift

@@ -121,10 +121,10 @@ public struct Environment {
     /// Environment fallback strategy.
     public static var fallbackStrategy: FallbackStrategy = .init(query: .configuration, fallback: .process)
 
-    // MARK: - Private
+    // MARK: - Storage
 
     /// Backing environment values.
-    private let values: OrderedDictionary<String, Value>
+    public private(set) var values: OrderedDictionary<String, Value>
 
     /// Process info instance.
     private let processInfo: ProcessInfo
@@ -163,6 +163,12 @@ public struct Environment {
             }
         self.processInfo = processInfo
     }
+
+    /// Create an empty environment.
+    /// - Parameter processInfo: Process info to seed the environment with.
+    public init(processInfo: ProcessInfo = ProcessInfo.processInfo) throws {
+        try self.init(values: [:] as OrderedDictionary<String, Value>, processInfo: processInfo)
+    }
 
     /// Create an environment from the contents of a file.
     /// - Parameter contents: File contents.
@@ -188,10 +194,46 @@ public struct Environment {
         self.values = values
         self.processInfo = processInfo
     }
+
+    // MARK: - Modifying the Environment
+
+    /// Set a new value in the environment for the given key, optionally specifiying if the value should overwrite an existing value, if any exists.
+    /// - Parameters:
+    ///   - value: Value to set in the environment.
+    ///   - key: Key to set value for.
+    ///   - force: Flag that indicates if the value should be forced if a value with the same key exists, defaults to `false`.
+    /// - Important: If the environment is set to read from the process, this method is a no-op as the process' environment is read-only.
+    public mutating func setValue(_ value: Value?, forKey key: String, force: Bool = false) {
+        guard values[key] == nil || force else {
+            return
+        }
+        values[key] = value
+    }
+
+    /// Set a new value in the environment for the given key, optionally specifiying if the value should overwrite an existing value, if any exists.
+    /// - Parameters:
+    ///   - value: Value to set in the environment.
+    ///   - key: Key to set value for.
+    ///   - force: Flag that indicates if the value should be forced if a value with the same key exists, defaults to `false`.
+    /// - Important: If the environment is set to read from the process, this method is a no-op as the process' environment is read-only.
+    public mutating func setValue(_ value: String, forKey key: String, force: Bool = false) {
+        setValue(Value(value), forKey: key, force: force)
+    }
+
+    /// Remove a value for the given key, returning the old value, if any exsts.
+    /// - Parameter key: Key to remove.
+    /// - Returns: Old value that was removed, if any.
+    @discardableResult
+    public mutating func removeValue(forKey key: String) -> Value? {
+        let oldValue = queryValue(forKey: key)
+        setValue(nil, forKey: key, force: true)
+        return oldValue
+    }
 
     // MARK: - Serialization
 
     /// Transform the environment into a string representation that can be written to disk.
+    /// - Important: If the environment is backed by the current process, this method will **not** serialize those values to disk, only those manually set via `setValue(_:forKey:force:)`.
     /// - Returns: File contents.
     func serialize() throws -> String {
         values.enumerated().reduce(into: "") { accumulated, current in
@@ -202,17 +244,29 @@ public struct Environment {
     // MARK: - Subscript
 
     public subscript(key: String) -> Value? {
-        queryValue(forKey: key)
+        get {
+            queryValue(forKey: key)
+        } set {
+            setValue(newValue, forKey: key)
+        }
     }
 
     public subscript(key: String, default defaultValue: @autoclosure () -> Value) -> Value {
-        queryValue(forKey: key) ?? defaultValue()
+        get {
+            queryValue(forKey: key) ?? defaultValue()
+        } set {
+            setValue(newValue, forKey: key)
+        }
     }
 
     // MARK: Dynamic Member Lookup
 
     public subscript(dynamicMember member: String) -> Value? {
-        queryValue(forKey: member)
+        get {
+            queryValue(forKey: member)
+        } set {
+            setValue(newValue, forKey: member)
+        }
     }
 
     // MARK: - Helpers

Tests/EnvironmentTests.swift

@@ -39,4 +39,64 @@ final class EnvironmentTests: XCTestCase {
         XCTAssertEqual(env.networkRetries, .integer(3))
         XCTAssertEqual(env.networkTimeout, .double(10.5))
     }
+
+    // MARK: - Adding and Removing Values
+
+    func testAddingValueForNonexistantKey() throws {
+        var environment = try Environment()
+
+        XCTAssertNil(environment.key)
+
+        environment.setValue(.integer(1), forKey: "key")
+
+        XCTAssertEqual(environment.key, .integer(1))
+    }
+
+    func testAddingValueForExistingKeyWithoutForcing() throws {
+        var environment = try Environment(values: [
+            "key": .integer(1)
+        ])
+
+        XCTAssertEqual(environment.key, .integer(1))
+
+        environment.setValue(.integer(2), forKey: "key")
+
+        XCTAssertEqual(environment.key, .integer(1))
+    }
+
+    func testAddingValueForExistingValueWithForcing() throws {
+        var environment = try Environment(values: [
+            "key": .integer(1)
+        ])
+
+        XCTAssertEqual(environment.key, .integer(1))
+
+        environment.setValue(.integer(2), forKey: "key", force: true)
+
+        XCTAssertEqual(environment.key, .integer(2))
+    }
+
+    func testRemovingNonexistantValue() throws {
+        var environment = try Environment()
+
+        XCTAssertNil(environment.key)
+
+        let oldValue = environment.removeValue(forKey: "key")
+
+        XCTAssertNil(oldValue)
+    }
+
+
+    func testRemovingValue() throws {
+        var environment = try Environment(values: [
+            "key": .integer(1)
+        ])
+
+        XCTAssertNotNil(environment.key)
+
+        let oldValue = environment.removeValue(forKey: "key")
+
+        XCTAssertEqual(oldValue, .integer(1))
+        XCTAssertNil(environment.key)
+    }
 }