diff --git a/Sources/Knit/Module/AbstractAssembly.swift b/Sources/Knit/Module/AbstractAssembly.swift
new file mode 100644
index 0000000..eca3f18
--- /dev/null
+++ b/Sources/Knit/Module/AbstractAssembly.swift
@@ -0,0 +1,8 @@
+//
+// Copyright © Block, Inc. All rights reserved.
+//
+
+import Foundation
+
+/// An AbstractAssembly can only contain abstract registrations and should not be initialised.
+protocol AbstractAssembly: ModuleAssembly { }
diff --git a/Sources/KnitCodeGen/AssemblyParsing.swift b/Sources/KnitCodeGen/AssemblyParsing.swift
index d99e999..f7658d8 100644
--- a/Sources/KnitCodeGen/AssemblyParsing.swift
+++ b/Sources/KnitCodeGen/AssemblyParsing.swift
@@ -51,6 +51,10 @@ func parseSyntaxTree(
         throw AssemblyParsingError.missingModuleName
     }
 
+    guard let assemblyType = assemblyFileVisitor.assemblyType else {
+        throw AssemblyParsingError.missingAssemblyType
+    }
+
     errorsToPrint.append(contentsOf: assemblyFileVisitor.assemblyErrors)
     errorsToPrint.append(contentsOf: assemblyFileVisitor.registrationErrors)
 
@@ -63,6 +67,7 @@ func parseSyntaxTree(
 
     return Configuration(
         name: name,
+        assemblyType: assemblyType,
         registrations: assemblyFileVisitor.registrations,
         registrationsIntoCollections: assemblyFileVisitor.registrationsIntoCollections,
         imports: assemblyFileVisitor.imports,
@@ -77,6 +82,8 @@ private class AssemblyFileVisitor: SyntaxVisitor, IfConfigVisitor {
 
     private(set) var moduleName: String?
 
+    private(set) var assemblyType: String?
+
     private var classDeclVisitor: ClassDeclVisitor?
 
     private(set) var assemblyErrors: [Error] = []
@@ -105,11 +112,11 @@ private class AssemblyFileVisitor: SyntaxVisitor, IfConfigVisitor {
     }
 
     override func visit(_ node: StructDeclSyntax) -> SyntaxVisitorContinueKind {
-        return visitAssemblyType(node)
+        return visitAssemblyType(node, node.inheritanceClause)
     }
 
     override func visit(_ node: ClassDeclSyntax) -> SyntaxVisitorContinueKind {
-        return visitAssemblyType(node)
+        return visitAssemblyType(node, node.inheritanceClause)
     }
 
     override func visit(_ node: ImportDeclSyntax) -> SyntaxVisitorContinueKind {
@@ -130,7 +137,7 @@ private class AssemblyFileVisitor: SyntaxVisitor, IfConfigVisitor {
         return self.visitIfNode(node)
     }
 
-    private func visitAssemblyType(_ node: NamedDeclSyntax) -> SyntaxVisitorContinueKind {
+    private func visitAssemblyType(_ node: NamedDeclSyntax, _ inheritance: InheritanceClauseSyntax?) -> SyntaxVisitorContinueKind {
         guard classDeclVisitor == nil else {
             // Only the first class declaration should be visited
             return .skipChildren
@@ -143,6 +150,10 @@ private class AssemblyFileVisitor: SyntaxVisitor, IfConfigVisitor {
         }
 
         moduleName = node.moduleNameForAssembly
+        let inheritedTypes = inheritance?.inheritedTypes.map {
+            $0.type.description.trimmingCharacters(in: .whitespaces)
+        }
+        self.assemblyType = inheritedTypes?.first(where: { $0.hasSuffix("Assembly")})
         classDeclVisitor = ClassDeclVisitor(viewMode: .fixedUp, directives: directives)
         classDeclVisitor?.walk(node)
         return .skipChildren
@@ -233,6 +244,7 @@ extension NamedDeclSyntax {
 enum AssemblyParsingError: Error {
     case fileReadError(Error, path: String)
     case missingModuleName
+    case missingAssemblyType
     case parsingError
 }
 
@@ -251,6 +263,8 @@ extension AssemblyParsingError: LocalizedError {
                 "Is your Assembly file setup correctly?"
         case .parsingError:
             return "There were one or more errors parsing the assembly file"
+        case .missingAssemblyType:
+            return "Assembly files must inherit from an *Assembly type"
         }
     }
 
diff --git a/Sources/KnitCodeGen/Configuration.swift b/Sources/KnitCodeGen/Configuration.swift
index 5596a8c..962b4f5 100644
--- a/Sources/KnitCodeGen/Configuration.swift
+++ b/Sources/KnitCodeGen/Configuration.swift
@@ -9,6 +9,7 @@ public struct Configuration: Encodable {
 
     /// Name of the module for this configuration.
     public var name: String
+    public var assemblyType: String
 
     public var registrations: [Registration]
     public var registrationsIntoCollections: [RegistrationIntoCollection]
@@ -18,12 +19,14 @@ public struct Configuration: Encodable {
 
     public init(
         name: String,
+        assemblyType: String = "Assembly",
         registrations: [Registration],
         registrationsIntoCollections: [RegistrationIntoCollection],
         imports: [ModuleImport] = [],
         targetResolver: String
     ) {
         self.name = name
+        self.assemblyType = assemblyType
         self.registrations = registrations
         self.registrationsIntoCollections = registrationsIntoCollections
         self.imports = imports
@@ -32,6 +35,7 @@ public struct Configuration: Encodable {
 
     public enum CodingKeys: CodingKey {
         case name
+        case assemblyType
         case registrations
     }
 
@@ -48,10 +52,6 @@ public extension Configuration {
     }
 
     func makeUnitTestSourceFile() throws -> SourceFileSyntax {
-        var allImports = imports
-        allImports.append(try .testable(name: name))
-        allImports.append(try .named("XCTest"))
-
         return try UnitTestSourceFile.make(
             configuration: self
         )
diff --git a/Tests/KnitCodeGenTests/AssemblyParsingTests.swift b/Tests/KnitCodeGenTests/AssemblyParsingTests.swift
index 4037972..5cba08d 100644
--- a/Tests/KnitCodeGenTests/AssemblyParsingTests.swift
+++ b/Tests/KnitCodeGenTests/AssemblyParsingTests.swift
@@ -13,7 +13,7 @@ final class AssemblyParsingTests: XCTestCase {
         let sourceFile: SourceFileSyntax = """
             import A
             import B // Comment after import should be stripped
-            class FooTestAssembly: Assembly { }
+            class FooTestAssembly: ModuleAssembly { }
             """
 
         let config = try assertParsesSyntaxTree(sourceFile)
@@ -25,6 +25,7 @@ final class AssemblyParsingTests: XCTestCase {
             ]
         )
         XCTAssertEqual(config.registrations.count, 0, "No registrations")
+        XCTAssertEqual(config.assemblyType, "ModuleAssembly")
     }
 
     func testDebugWrappedAssemblyImports() throws {
@@ -108,6 +109,7 @@ final class AssemblyParsingTests: XCTestCase {
 
         let config = try assertParsesSyntaxTree(sourceFile)
         XCTAssertEqual(config.name, "FooTest")
+        XCTAssertEqual(config.assemblyType, "Assembly")
     }
 
     func testAssemblyStructModuleName() throws {