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368 lines
10 KiB
JavaScript
368 lines
10 KiB
JavaScript
"use strict";
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const chai = require( "chai" );
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const peg = require( "pegjs" );
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const sinon = require( "sinon" );
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const expect = chai.expect;
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describe( "PEG.js API", function () {
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describe( "generate", function () {
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it( "generates a parser", function () {
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const parser = peg.generate( "start = 'a'" );
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expect( parser ).to.be.an( "object" );
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expect( parser.parse( "a" ) ).to.equal( "a" );
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} );
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it( "throws an exception on syntax error", function () {
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expect( () => {
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peg.generate( "start = @" );
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} ).to.throw();
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} );
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it( "throws an exception on semantic error", function () {
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expect( () => {
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peg.generate( "start = undefined" );
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} ).to.throw();
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} );
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describe( "allowed start rules", function () {
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const grammar = `
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a = 'x'
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b = 'x'
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c = 'x'
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`;
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it( "throws an error on missing rule", function () {
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expect( () => {
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peg.generate( grammar, { allowedStartRules: [ "missing" ] } );
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} ).to.throw();
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} );
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// The |allowedStartRules| option is implemented separately for each
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// optimization mode, so we need to test it in both.
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describe( "when optimizing for parsing speed", function () {
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describe( "when |allowedStartRules| is not set", function () {
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it( "generated parser can start only from the first rule", function () {
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const parser = peg.generate( grammar, { optimize: "speed" } );
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expect( parser.parse( "x", { startRule: "a" } ) ).to.equal( "x" );
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expect( () => {
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parser.parse( "x", { startRule: "b" } );
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} ).to.throw();
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expect( () => {
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parser.parse( "x", { startRule: "c" } );
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} ).to.throw();
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} );
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} );
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describe( "when |allowedStartRules| is set", function () {
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it( "generated parser can start only from specified rules", function () {
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const parser = peg.generate( grammar, {
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optimize: "speed",
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allowedStartRules: [ "b", "c" ],
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} );
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expect( () => {
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parser.parse( "x", { startRule: "a" } );
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} ).to.throw();
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expect( parser.parse( "x", { startRule: "b" } ) ).to.equal( "x" );
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expect( parser.parse( "x", { startRule: "c" } ) ).to.equal( "x" );
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} );
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} );
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} );
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describe( "when optimizing for code size", function () {
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describe( "when |allowedStartRules| is not set", function () {
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it( "generated parser can start only from the first rule", function () {
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const parser = peg.generate( grammar, { optimize: "size" } );
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expect( parser.parse( "x", { startRule: "a" } ) ).to.equal( "x" );
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expect( () => {
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parser.parse( "x", { startRule: "b" } );
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} ).to.throw();
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expect( () => {
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parser.parse( "x", { startRule: "c" } );
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} ).to.throw();
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} );
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} );
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describe( "when |allowedStartRules| is set", function () {
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it( "generated parser can start only from specified rules", function () {
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const parser = peg.generate( grammar, {
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optimize: "size",
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allowedStartRules: [ "b", "c" ],
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} );
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expect( () => {
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parser.parse( "x", { startRule: "a" } );
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} ).to.throw();
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expect( parser.parse( "x", { startRule: "b" } ) ).to.equal( "x" );
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expect( parser.parse( "x", { startRule: "c" } ) ).to.equal( "x" );
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} );
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} );
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} );
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} );
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describe( "intermediate results caching", function () {
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const grammar = `
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{ var n = 0; }
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start = (a 'b') / (a 'c') { return n; }
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a = 'a' { n++; }
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`;
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describe( "when |cache| is not set", function () {
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it( "generated parser doesn't cache intermediate parse results", function () {
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const parser = peg.generate( grammar );
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expect( parser.parse( "ac" ) ).to.equal( 2 );
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} );
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} );
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describe( "when |cache| is set to |false|", function () {
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it( "generated parser doesn't cache intermediate parse results", function () {
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const parser = peg.generate( grammar, { cache: false } );
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expect( parser.parse( "ac" ) ).to.equal( 2 );
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} );
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} );
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describe( "when |cache| is set to |true|", function () {
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it( "generated parser caches intermediate parse results", function () {
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const parser = peg.generate( grammar, { cache: true } );
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expect( parser.parse( "ac" ) ).to.equal( 1 );
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} );
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} );
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} );
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describe( "tracing", function () {
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const grammar = "start = 'a'";
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describe( "when |trace| is not set", function () {
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it( "generated parser doesn't trace", function () {
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const parser = peg.generate( grammar );
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const tracer = { trace: sinon.spy() };
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parser.parse( "a", { tracer: tracer } );
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expect( tracer.trace.called ).to.equal( false );
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} );
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} );
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describe( "when |trace| is set to |false|", function () {
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it( "generated parser doesn't trace", function () {
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const parser = peg.generate( grammar, { trace: false } );
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const tracer = { trace: sinon.spy() };
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parser.parse( "a", { tracer: tracer } );
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expect( tracer.trace.called ).to.equal( false );
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} );
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} );
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describe( "when |trace| is set to |true|", function () {
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it( "generated parser traces", function () {
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const parser = peg.generate( grammar, { trace: true } );
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const tracer = { trace: sinon.spy() };
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parser.parse( "a", { tracer: tracer } );
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expect( tracer.trace.called ).to.equal( true );
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} );
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} );
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} );
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// The |optimize| option isn't tested because there is no meaningful way to
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// write the tests without turning this into a performance test.
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describe( "output", function () {
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const grammar = "start = 'a'";
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describe( "when |output| is not set", function () {
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it( "returns generated parser object", function () {
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const parser = peg.generate( grammar );
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expect( parser ).to.be.an( "object" );
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expect( parser.parse( "a" ) ).to.equal( "a" );
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} );
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} );
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describe( "when |output| is set to |\"parser\"|", function () {
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it( "returns generated parser object", function () {
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const parser = peg.generate( grammar, { output: "parser" } );
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expect( parser ).to.be.an( "object" );
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expect( parser.parse( "a" ) ).to.equal( "a" );
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} );
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} );
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describe( "when |output| is set to |\"source\"|", function () {
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it( "returns generated parser source code", function () {
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const source = peg.generate( grammar, { output: "source" } );
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expect( source ).to.be.a( "string" );
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expect( eval( source ).parse( "a" ) ).to.equal( "a" );
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} );
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} );
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} );
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// The |format|, |exportVars|, and |dependencies| options are not tested
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// becasue there is no meaningful way to thest their effects without turning
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// this into an integration test.
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// The |plugins| option is tested in plugin API tests.
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describe( "reserved words", function () {
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const RESERVED_WORDS = peg.util.reservedWords;
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describe( "throws an exception on reserved JS words used as labels", function () {
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for ( const label of RESERVED_WORDS ) {
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it( label, function () {
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expect( () => {
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peg.generate( [
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"start = " + label + ":end",
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"end = 'a'",
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].join( "\n" ), { output: "source" } );
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} ).to.throw( peg.parser.SyntaxError );
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} );
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}
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} );
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describe( "not throws an exception on reserved JS words used as rule name", function () {
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for ( const rule of RESERVED_WORDS ) {
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it( rule, function () {
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expect( () => {
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peg.generate( [
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"start = " + rule,
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rule + " = 'a'",
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].join( "\n" ), { output: "source" } );
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} ).to.not.throw( peg.parser.SyntaxError );
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} );
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}
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} );
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} );
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it( "accepts custom options", function () {
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peg.generate( "start = 'a'", { foo: 42 } );
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} );
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} );
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} );
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