test: cover parser pipeline (#67)

Author: DongyuZhao

Tests/SwiftParserTests/ParserPipelineTests.swift

@@ -0,0 +1,156 @@
+import XCTest
+@testable import SwiftParser
+
+final class ParserPipelineTests: XCTestCase {
+    enum SimpleTokenElement: String, CaseIterable, CodeTokenElement {
+        case number
+        case plus
+        case eof
+    }
+
+    struct SimpleToken: CodeToken {
+        typealias Element = SimpleTokenElement
+        let element: SimpleTokenElement
+        let text: String
+        let range: Range<String.Index>
+    }
+
+    struct NumberTokenBuilder: CodeTokenBuilder {
+        typealias Token = SimpleTokenElement
+        func build(from context: inout CodeTokenContext<Token>) -> Bool {
+            guard context.consuming < context.source.endIndex,
+                  context.source[context.consuming].isNumber else { return false }
+            var end = context.consuming
+            while end < context.source.endIndex && context.source[end].isNumber {
+                end = context.source.index(after: end)
+            }
+            let range = context.consuming..<end
+            let token = SimpleToken(element: .number,
+                                    text: String(context.source[range]),
+                                    range: range)
+            context.tokens.append(token)
+            context.consuming = end
+            return true
+        }
+    }
+
+    struct PlusTokenBuilder: CodeTokenBuilder {
+        typealias Token = SimpleTokenElement
+        func build(from context: inout CodeTokenContext<Token>) -> Bool {
+            guard context.consuming < context.source.endIndex,
+                  context.source[context.consuming] == "+" else { return false }
+            let start = context.consuming
+            context.consuming = context.source.index(after: start)
+            let token = SimpleToken(element: .plus, text: "+", range: start..<context.consuming)
+            context.tokens.append(token)
+            return true
+        }
+    }
+
+    struct WhitespaceTokenBuilder: CodeTokenBuilder {
+        typealias Token = SimpleTokenElement
+        func build(from context: inout CodeTokenContext<Token>) -> Bool {
+            guard context.consuming < context.source.endIndex,
+                  context.source[context.consuming].isWhitespace else { return false }
+            context.consuming = context.source.index(after: context.consuming)
+            return true
+        }
+    }
+
+    enum SimpleNodeElement: String, CaseIterable, CodeNodeElement {
+        case root
+        case number
+    }
+
+    struct NumberNodeBuilder: CodeNodeBuilder {
+        typealias Node = SimpleNodeElement
+        typealias Token = SimpleTokenElement
+        func build(from context: inout CodeConstructContext<Node, Token>) -> Bool {
+            guard context.consuming < context.tokens.count,
+                  let token = context.tokens[context.consuming] as? SimpleToken,
+                  token.element == .number else { return false }
+            let node = CodeNode<Node>(element: .number)
+            context.current.append(node)
+            context.consuming += 1
+            return true
+        }
+    }
+
+    struct SimpleLanguage: CodeLanguage {
+        typealias Node = SimpleNodeElement
+        typealias Token = SimpleTokenElement
+
+        var tokens: [any CodeTokenBuilder<Token>] {
+            [WhitespaceTokenBuilder(), NumberTokenBuilder(), PlusTokenBuilder()]
+        }
+        var nodes: [any CodeNodeBuilder<Node, Token>] { [NumberNodeBuilder()] }
+
+        func root() -> CodeNode<Node> { CodeNode<Node>(element: .root) }
+        func state() -> (any CodeConstructState<Node, Token>)? { nil }
+        func state() -> (any CodeTokenState<Token>)? { nil }
+        // rely on default eof implementation
+    }
+
+    func testTokenizerProducesTokensAndErrors() {
+        let tokenizer = CodeTokenizer(
+            builders: [NumberTokenBuilder(), PlusTokenBuilder()],
+            state: { nil },
+            eof: { SimpleToken(element: .eof, text: "", range: $0) }
+        )
+
+        let (tokens, errors) = tokenizer.tokenize("1+a")
+        XCTAssertEqual(tokens.count, 3) // number, plus, eof
+        XCTAssertEqual((tokens[0] as? SimpleToken)?.text, "1")
+        XCTAssertEqual((tokens[1] as? SimpleToken)?.element, .plus)
+        XCTAssertEqual((tokens[2] as? SimpleToken)?.element, .eof)
+        XCTAssertEqual(errors.count, 1)
+    }
+
+    func testConstructorBuildsNodesAndErrors() {
+        let oneRange = "1".startIndex..<"1".endIndex
+        let plusRange = "+".startIndex..<"+".endIndex
+        let twoRange = "2".startIndex..<"2".endIndex
+        let tokens: [any CodeToken<SimpleTokenElement>] = [
+            SimpleToken(element: .number, text: "1", range: oneRange),
+            SimpleToken(element: .plus, text: "+", range: plusRange),
+            SimpleToken(element: .number, text: "2", range: twoRange)
+        ]
+        let root = CodeNode<SimpleNodeElement>(element: .root)
+        let constructor = CodeConstructor(builders: [NumberNodeBuilder()], state: { nil })
+        let (parsed, errors) = constructor.parse(tokens, root: root)
+        XCTAssertEqual(parsed.children.count, 2)
+        XCTAssertEqual(errors.count, 1) // plus token unrecognized
+    }
+
+    func testParserNormalizesAndParses() {
+        let language = SimpleLanguage()
+        let parser = CodeParser(language: language)
+        let result = parser.parse("1\r\n2\r", language: language)
+        XCTAssertEqual(result.root.children.count, 2)
+        XCTAssertTrue(result.errors.isEmpty)
+        XCTAssertEqual(result.tokens.count, 2)
+        // ensure default eof returns nil
+        XCTAssertNil(language.eof(at: "".startIndex..<"".endIndex))
+    }
+
+    func testContextAndErrorInitialization() {
+        let tokenContext = CodeTokenContext<SimpleTokenElement>(source: "1")
+        XCTAssertEqual(tokenContext.source, "1")
+        XCTAssertTrue(tokenContext.tokens.isEmpty)
+        XCTAssertTrue(tokenContext.errors.isEmpty)
+
+        let root = CodeNode<SimpleNodeElement>(element: .root)
+        let constructContext = CodeConstructContext<SimpleNodeElement, SimpleTokenElement>(
+            current: root, tokens: []
+        )
+        XCTAssertTrue(constructContext.current === root)
+        XCTAssertEqual(constructContext.tokens.count, 0)
+        XCTAssertEqual(constructContext.consuming, 0)
+        XCTAssertTrue(constructContext.errors.isEmpty)
+
+        let error = CodeError("msg", range: "a".startIndex..<"a".startIndex)
+        XCTAssertEqual(error.message, "msg")
+        XCTAssertNotNil(error.range)
+    }
+}
+