[DependencyResolver] Provide constraints in resolve(), not init.

Author: ddunbar

Sources/PackageGraph/DependencyResolver.swift

@@ -509,27 +509,24 @@ public class DependencyResolver<
     /// only kind of constraints we operate on.
     public typealias Constraint = PackageContainerConstraint<Identifier>
 
-    /// The initial constraints.
-    public let constraints: [Constraint]
 
     /// The container provider used to load package containers.
     public let provider: Provider
 
     /// The resolver's delegate.
     public let delegate: Delegate
 
-    public init(
-        constraints: [Constraint],
-        provider: Provider,
-        delegate: Delegate)
-    {
-        self.constraints = constraints
+    public init(_ provider: Provider, _ delegate: Delegate) {
         self.provider = provider
         self.delegate = delegate
     }
 
     /// Execute the resolution algorithm to find a valid assignment of versions.
-    public func resolve() throws -> [(container: Identifier, version: Version)] {
+    ///
+    /// - Parameters:
+    ///   - constraints: The contraints to solve.
+    /// - Returns: A satisfying assignment of containers and versions.
+    public func resolve(constraints: [Constraint]) throws -> [(container: Identifier, version: Version)] {
         // For now, we just load the transitive closure of the dependencies at
         // the latest version, and ignore the version requirements.
 

Tests/PackageGraphTests/DependencyResolverTests.swift

@@ -97,11 +97,9 @@ class DependencyResolverTests: XCTestCase {
                         v1: [], v2: []])])
 
         let delegate = MockResolverDelegate()
-        let resolver = DependencyResolver(
-            constraints: [MockPackageConstraint(container: "A", versionRequirement: v1Range)],
-            provider: provider,
-            delegate: delegate)
-        let packages = try resolver.resolve()
+        let resolver = DependencyResolver(provider, delegate)
+        let packages = try resolver.resolve(constraints: [
+                MockPackageConstraint(container: "A", versionRequirement: v1Range)])
         XCTAssertEqual(packages.map{ $0.container }.sorted(), ["A", "B", "C"])
         XCTAssertEqual(delegate.messages, [
                 "added container: A",