fix: fqn resolution of artifacts

In the artifact resolver detect whether a FQN is being used to refer to the
contract and use Hardhat's own build info resolution method as we can rely on
the fqn.

This is now covered with an additional integration test for repos with multiple
contracts with the same name in different files and an Ignition module where
those contracts are referred to by FQNs.

Fixes #778.

packages/hardhat-plugin/src/hardhat-artifact-resolver.ts

@@ -14,6 +14,17 @@ export class HardhatArtifactResolver implements ArtifactResolver {
   public async getBuildInfo(
     contractName: string
   ): Promise<BuildInfo | undefined> {
+    // If a fully qualified name is used, we can can
+    // leverage the artifact manager directly to load the build
+    // info.
+    if (this._isFullyQualifiedName(contractName)) {
+      return this._hre.artifacts.getBuildInfo(contractName);
+    }
+
+    // Otherwise we have only the contract name, and need to
+    // resolve the artifact for the contract ourselves.
+    // We can build on the assumption that the contract name
+    // is unique based on Module validation.
     const artifactPath = await this._resolvePath(contractName);
 
     if (artifactPath === undefined) {
@@ -51,4 +62,14 @@ export class HardhatArtifactResolver implements ArtifactResolver {
   public loadArtifact(contractName: string): Promise<Artifact> {
     return this._hre.artifacts.readArtifact(contractName);
   }
+
+  /**
+   * Returns true if a name is fully qualified, and not just a bare contract name.
+   *
+   * This is based on Hardhat's own test for fully qualified names, taken
+   * from `contract-names.ts` in `hardhat-core` utils.
+   */
+  private _isFullyQualifiedName(contractName: string): boolean {
+    return contractName.includes(":");
+  }
 }

packages/hardhat-plugin/test/fixture-projects/multiple-contracts-with-same-name/contracts/Rocket1.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+// This contract name is the same as in `./Rocket2.sol`
+contract Rocket {
+    string public name;
+
+    constructor(string memory _name) {
+        name = _name;
+    }
+}

packages/hardhat-plugin/test/fixture-projects/multiple-contracts-with-same-name/contracts/Rocket2.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+// This contract name is the same as in `./Rocket1.sol`
+contract Rocket {
+    string public name;
+
+    constructor(string memory _name) {
+        name = _name;
+    }
+}

packages/hardhat-plugin/test/fixture-projects/multiple-contracts-with-same-name/hardhat.config.js

@@ -0,0 +1,5 @@
+require("../../../src/index");
+
+module.exports = {
+  solidity: "0.8.19",
+};

packages/hardhat-plugin/test/module-api/fully-qualified-names.ts

@@ -0,0 +1,39 @@
+import { buildModule } from "@nomicfoundation/ignition-core";
+import { assert } from "chai";
+
+import { useFileIgnitionProject } from "../test-helpers/use-ignition-project";
+
+describe("fully qualified names", () => {
+  describe("where there are multiple contracts with the same name in the project", () => {
+    useFileIgnitionProject(
+      "multiple-contracts-with-same-name",
+      "contract-deploy"
+    );
+
+    it("should deploy contracts by referring using fully qualified names", async function () {
+      const LaunchModule = buildModule("Apollo", (m) => {
+        const rocket1 = m.contract(
+          "contracts/Rocket1.sol:Rocket",
+          ["Rocket 1"],
+          {
+            id: "Rocket1",
+          }
+        );
+        const rocket2 = m.contract(
+          "contracts/Rocket2.sol:Rocket",
+          ["Rocket 2"],
+          {
+            id: "Rocket2",
+          }
+        );
+
+        return { rocket1, rocket2 };
+      });
+
+      const result = await this.hre.ignition.deploy(LaunchModule);
+
+      assert.equal(await result.rocket1.read.name(), "Rocket 1");
+      assert.equal(await result.rocket2.read.name(), "Rocket 2");
+    });
+  });
+});