New lexer for mojom written in go.

mojom/mojom_parser/lexer/lexer_test.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package lexer
 
 import "testing"
 
-// TODO(rudominer) This dummy test is here in order to be able to test the
-// go unit test infrastructure. It will eventually be replaced by a real test.
-func TestDummyLexerTest(t *testing.T) {
-        if 5.1 > 2.1*3.1 {
-                t.Fatalf("Something is wrong.")
-        }
-}
+func checkEq(t *testing.T, expected, actual interface{}) {
+        if expected != actual {
+                t.Fatalf("Failed check: Expected (%v), Actual (%v)", expected, actual)
+        }
+}
+
+// pumpTokens pumps all the tokens from a channel into a slice.
+func pumpTokens(tokensChan chan Token) []Token {
+        tokens := []Token{}
+        for token := range tokensChan {
+                tokens = append(tokens, token)
+        }
+        return tokens
+}
+
+// TestAllSingleTokens tests for each token that a valid string is accepted as
+// the correct token.
+func TestAllSingleTokens(t *testing.T) {
+        testData := []struct {
+                source string
+                token  TokenKind
+        }{
+                {"(", LParen},
+                {")", RParen},
+                {"[", LBracket},
+                {"]", RBracket},
+                {"{", LBrace},
+                {"}", RBrace},
+                {"<", LAngle},
+                {">", RAngle},
+                {";", Semi},
+                {",", Comma},
+                {".", Dot},
+                {"-", Minus},
+                {"+", Plus},
+                {"&", Amp},
+                {"?", Qstn},
+                {"=", Equals},
+                {"=>", Response},
+                {"somet_hi3ng", Name},
+                {"import", Import},
+                {"module", Module},
+                {"struct", Struct},
+                {"union", Union},
+                {"interface", Interface},
+                {"enum", Enum},
+                {"const", Const},
+                {"true", True},
+                {"false", False},
+                {"default", Default},
+                {"@10", Ordinal},
+                {"10", IntConstDec},
+                {"0", IntConstDec},
+                {"0xA10", IntConstHex},
+                {"0xa10", IntConstHex},
+                {"0XA10", IntConstHex},
+                {"0Xa10", IntConstHex},
+                {"10.5", FloatConst},
+                {"10e5", FloatConst},
+                {"0.5", FloatConst},
+                {"0e5", FloatConst},
+                {"10e+5", FloatConst},
+                {"10e-5", FloatConst},
+                {"\"hello world\"", StringLiteral},
+                {"\"hello \\\"real\\\" world\"", StringLiteral},
+        }
+
+        for i := range testData {
+                l := lexer{source: testData[i].source, tokens: make(chan Token)}
+                go l.run()
+                tokens := pumpTokens(l.tokens)
+
+                if len(tokens) != 1 {
+                        t.Fatalf("Source('%v'): Expected 1 token but got %v instead: %v",
+                                testData[i].source, len(tokens), tokens)
+                }
+
+                checkEq(t, testData[i].source, tokens[0].Text)
+                checkEq(t, testData[i].token, tokens[0].Kind)
+        }
+}
+
+// TestTokenPosition tests that the position in the source string, the line
+// number and the position in the line of the lexed token are correctly found.
+func TestTokenPosition(t *testing.T) {
+        source := "  \n  ."
+        l := lexer{source: source, tokens: make(chan Token)}
+        go l.run()
+        tokens := pumpTokens(l.tokens)
+        token := tokens[0]
+
+        checkEq(t, 5, token.CharPos)
+        checkEq(t, 1, token.LineNo)
+        checkEq(t, 2, token.LinePos)
+}
+
+// TestTokenPositionChineseString tests that CharPos is expressed as a number
+// of runes and not a number of bytes.
+func TestTokenPositionChineseString(t *testing.T) {
+        source := "\"您好\" is"
+        ts := Tokenize(source)
+        checkEq(t, StringLiteral, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, 5, ts.PeekNext().CharPos)
+}
+
+// TestSkipSkippable tests that all skippable characters are skipped.
+func TestSkipSkippable(t *testing.T) {
+        source := "  \t  \r \n  ."
+        l := lexer{source: source, tokens: make(chan Token)}
+        go l.run()
+        tokens := pumpTokens(l.tokens)
+
+        checkEq(t, Dot, tokens[0].Kind)
+}
+
+// TestTokenize tests that a single token embedded in a larger string is
+// correctly lexed.
+func TestTokenize(t *testing.T) {
+        ts := Tokenize("   \t .   ")
+        token := ts.PeekNext()
+        checkEq(t, Dot, token.Kind)
+
+        ts.ConsumeNext()
+        token = ts.PeekNext()
+        checkEq(t, EOF, token.Kind)
+}
+
+// TestTokenizeBadUTF8String tests that an invalid UTF8 string is handled.
+func TestTokenizeBadUTF8String(t *testing.T) {
+        ts := Tokenize("\xF0")
+        checkEq(t, ErrorIllegalChar, ts.PeekNext().Kind)
+}
+
+// TestTokenizeEmptyString tests that empty strings are handled correctly.
+func TestTokenizeEmptyString(t *testing.T) {
+        ts := Tokenize("")
+        checkEq(t, EOF, ts.PeekNext().Kind)
+}
+
+// TestTokenizeMoreThanOne tests that more than one token is correctly lexed.
+func TestTokenizeMoreThanOne(t *testing.T) {
+        ts := Tokenize("()")
+        checkEq(t, LParen, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, RParen, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, EOF, ts.PeekNext().Kind)
+}
+
+// TestIllegalChar tests that an illegal character is correctly spotted.
+func TestIllegalChar(t *testing.T) {
+        ts := Tokenize("   \t $   ")
+        checkEq(t, ErrorIllegalChar, ts.PeekNext().Kind)
+}
+
+// TestUnterminatedStringLiteralEos tests that the correct error is emitted if
+// a quoted string is never closed.
+func TestUnterminatedStringLiteralEos(t *testing.T) {
+        ts := Tokenize("\"hello world")
+        checkEq(t, ErrorUnterminatedStringLiteral, ts.PeekNext().Kind)
+}
+
+// TestUnterminatedStringLiteralEol tests that the correct error is emitted if
+// a quoted string is closed on a subsequent line.
+func TestUnterminatedStringLiteralEol(t *testing.T) {
+        ts := Tokenize("\"hello\n world\"")
+        checkEq(t, ErrorUnterminatedStringLiteral, ts.PeekNext().Kind)
+}
+
+// TestSingleLineComment tests that single line comments are correctly skipped.
+func TestSingleLineComment(t *testing.T) {
+        ts := Tokenize("( // some stuff\n)")
+        checkEq(t, LParen, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, RParen, ts.PeekNext().Kind)
+}
+
+// TestMultiLineComment tests that multi line comments are correctly skipped.
+func TestMultiLineComment(t *testing.T) {
+        ts := Tokenize("( /* hello world/  * *\n */)")
+        checkEq(t, LParen, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, RParen, ts.PeekNext().Kind)
+}
+
+// TestUnterminatedMultiLineComment tests that unterminated multiline comments
+// emit the correct error.
+func TestUnterminatedMultiLineComment(t *testing.T) {
+        ts := Tokenize("( /* hello world/  * *\n )")
+        checkEq(t, LParen, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, ErrorUnterminatedComment, ts.PeekNext().Kind)
+}
+
+// TestUnterminatedMultiLineCommentAtStar tests that if the string ends at a *
+// (which could be the beginning of the close of a multiline comment) the right
+// error is emitted.
+func TestUnterminatedMultiLineCommentAtStar(t *testing.T) {
+        ts := Tokenize("( /* hello world/  *")
+        checkEq(t, LParen, ts.PeekNext().Kind)
+        ts.ConsumeNext()
+        checkEq(t, ErrorUnterminatedComment, ts.PeekNext().Kind)
+}