Adds testing infrastructure

Author: stevapple

.github/workflows/build.yml

@@ -17,3 +17,6 @@ jobs:
         uses: actions/checkout@v3
       - name: Build
         run: swift build -c ${{ matrix.build-config }}
+      - name: Test
+        if: ${{ matrix.build-config == 'debug' }}
+        run: swift test

Package.swift

@@ -76,5 +76,10 @@ let package = Package(
             dependencies: [
                 .byName(name: "TecoCodeGeneratorCommons"),
             ]),
+        .target(
+            name: "TecoCodeGeneratorTestHelpers",
+            dependencies: [
+                .byName(name: "TecoCodeGeneratorCommons"),
+            ]),
     ]
 )

Sources/TecoCodeGeneratorTestHelpers/AssertBuilder.swift

@@ -0,0 +1,38 @@
+import SwiftSyntax
+@_implementationOnly import TecoCodeGeneratorCommons
+import XCTest
+
+private func buildSyntax(_ buildable: some SyntaxProtocol) -> [String] {
+    // Format the code.
+    let source = buildable.formatted(using: CodeGenerationFormat())
+
+    // Work around styling issues regarding blank lines.
+    let code = source.description.trimmingCharacters(in: .whitespacesAndNewlines)
+
+    // Work around styling issues regarding trailing whitespaces.
+    return code.split(omittingEmptySubsequences: false, whereSeparator: \.isNewline).map {
+        var line = $0
+        while line.last?.isWhitespace == true {
+            line.removeLast()
+        }
+        return String(line)
+    }
+}
+
+public func AssertBuilder(_ buildable: some SyntaxProtocol, _ result: String) {
+    // Format the code.
+    let code = buildSyntax(buildable).joined(separator: "\n")
+
+    // Assert build result
+    XCTAssertEqual(code, result)
+}
+
+public func AssertBuilder(_ buildable: some SyntaxProtocol, contains lines: [String]) {
+    // Format the code.
+    let code = buildSyntax(buildable)
+
+    // Assert build result
+    for line in lines {
+        XCTAssertTrue(code.contains(line))
+    }
+}