Fix SwiftDocC integration test (#101)

The integration test as currently written fails to actually compile
any documentation because the Symbol Graph files for the test Swift Package
are never built.

This updates the test to build Symbol Graph files for the test package,
convert it, and assert that produced DocC documentation contains the expected
`data` subdirectory.

Resolves rdar://91638258.

Author: ethan-kusters

test-swift-docc/DocCTest/Package.swift

@@ -6,23 +6,9 @@ import PackageDescription
 let package = Package(
     name: "DocCTest",
     products: [
-        // Products define the executables and libraries a package produces, and make them visible to other packages.
-        .library(
-            name: "DocCTest",
-            targets: ["DocCTest"]),
-    ],
-    dependencies: [
-        // Dependencies declare other packages that this package depends on.
-        // .package(url: /* package url */, from: "1.0.0"),
+        .library(name: "DocCTest", targets: ["DocCTest"]),
     ],
     targets: [
-        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
-        // Targets can depend on other targets in this package, and on products in packages this package depends on.
-        .target(
-            name: "DocCTest",
-            dependencies: []),
-        .testTarget(
-            name: "DocCTestTests",
-            dependencies: ["DocCTest"]),
+        .target(name: "DocCTest"),
     ]
 )

test-swift-docc/DocCTest/Tests/DocCTestTests/DocCTestTests.swift

@@ -1,8 +1,18 @@
-// Check Swift-DocC can compile and preview documentation.
-//
-// RNU: rm -rf %S/Output
-// RUN: %{docc} convert %S/DocCTest/Sources/DocCTest/DocCTest.docc --output-path %S/Output
-// RUN: ls %S/Output
-
-// REQUIRES: rdar91638258
-
+// Check that Swift-DocC can compile documentation.
+//
+// Clear any existing state:
+// RUN: rm -rf %t.dir
+// RUN: mkdir -p %t.dir
+//
+// Build symbol graphs for the test package:
+// RUN: mkdir %t.dir/symbol-graph-directory
+// RUN: mkdir %t.dir/swiftpm-build-directory
+// RUN: %{swift} build --target DocCTest --package-path %S/DocCTest --build-path %t.dir/swiftpm-build-directory -Xswiftc -emit-symbol-graph -Xswiftc -emit-symbol-graph-dir -Xswiftc %t.dir/symbol-graph-directory
+//
+// Convert the documentation
+// RUN: %{docc} convert %S/DocCTest/Sources/DocCTest/DocCTest.docc --output-path %t.dir/DocCTest.doccarchive --additional-symbol-graph-dir %t.dir/symbol-graph-directory
+//
+// Assert that the produced documentation archive has a 'data' subdirectory as expected
+// RUN: ls %t.dir/DocCTest.doccarchive/data
+// RUN: ls %t.dir/DocCTest.doccarchive/data/documentation/docctest
+// RUN: ls %t.dir/DocCTest.doccarchive/data/documentation/docctest/docctest/variable.json