Seed initial test target.

Package.swift

@@ -17,6 +17,9 @@ let package = Package(
         .target(
             name: "GPUImage",
             resources: [.process("Resources")]
-        )
+        ),
+        .testTarget(
+            name: "GPUImageTests",
+            dependencies: ["GPUImage"]),
     ]
 )

Tests/GPUImageTests/MatrixTests.swift

@@ -0,0 +1,16 @@
+import XCTest
+@testable import GPUImage
+
+final class MatrixTests: XCTestCase {
+    func testMatrix3x3() throws {
+        let newMatrix = Matrix3x3(rowMajorValues: [
+            1.0, 2.0, 3.0,
+            4.0, 5.0, 6.0,
+            7.0, 8.0, 9.0
+        ])
+
+        XCTAssertEqual(newMatrix.m11, 1.0)
+        XCTAssertEqual(newMatrix.m23, 6.0)
+        XCTAssertEqual(newMatrix.m32, 8.0)
+    }
+}