Use execution timezone offset for ToDateTime(String)

src/datatypes/datetime.ts

@@ -289,7 +289,7 @@ export class DateTime extends AbstractDate {
     DateTime.Unit.MILLISECOND
   ];
 
-  static parse(string: any) {
+  static parse(string: any, defaultTimezoneOffset?: Decimal | number | null) {
     if (string === null) {
       return null;
     }
@@ -330,6 +330,8 @@ export class DateTime extends AbstractDate {
       args.push(matches[17] === '+' ? num : num * -1);
     } else if (matches[15] === 'Z') {
       args.push(0);
+    } else if (defaultTimezoneOffset != null) {
+      args.push(Decimal.from(defaultTimezoneOffset).toNumber());
     }
     // @ts-ignore
     return new DateTime(...args);

src/elm/type.ts

@@ -162,7 +162,7 @@ export class ToDateTime extends Expression {
       const timezoneOffset = ctx.getExecutionDateTime().timezoneOffset;
       return arg.getDateTime(timezoneOffset);
     } else {
-      return DateTime.parse(arg.toString());
+      return DateTime.parse(arg.toString(), ctx.getExecutionDateTime().timezoneOffset);
     }
   }
 }

test/datatypes/datetime-test.ts

@@ -146,6 +146,20 @@ describe('DateTime', () => {
     d.should.eql(new DateTime(2012, 10, 25, 12, 55, 14, 953, 0));
   });
 
+  it('should use the default timezone offset when the string has none', () => {
+    // use a quarter-hour offset that no real-world timezone has, so it can
+    // never coincide with the host machine's offset
+    const d = DateTime.parse('2012-10-25T12:55', -3.25);
+    d.timezoneOffset.should.equalDecimal(-3.25);
+  });
+
+  it('should ignore the default timezone offset when the string specifies one', () => {
+    let d = DateTime.parse('2012-10-25T12:55+05:30', -3.25);
+    d.timezoneOffset.should.equalDecimal(5.5);
+    d = DateTime.parse('2012-10-25T12:55Z', -3.25);
+    d.timezoneOffset.should.equalDecimal(0);
+  });
+
   it('should toString yyyy', () => {
     const d = new DateTime(2012);
     d.toString().should.eql('2012');

test/elm/convert/convert-test.ts

@@ -6,6 +6,7 @@ import { DateTime } from '../../../src/datatypes/datetime';
 import { Quantity } from '../../../src/datatypes/quantity';
 import { Uncertainty } from '../../../src/datatypes/uncertainty';
 import { Decimal } from '../../../src/datatypes/decimal';
+import { PatientContext } from '../../../src/runtime/context';
 
 describe('FromString', () => {
   beforeEach(function () {
@@ -92,6 +93,21 @@ describe('FromString', () => {
     date.isDateTime.should.equal(true);
   });
 
+  it("should convert '2015-01-02' to DateTime using the execution timezone offset", async function () {
+    this.ctx = new PatientContext(
+      this.ctx.library,
+      this.ctx.patient,
+      this.ctx.codeService,
+      this.ctx.parameters,
+      // use a quarter-hour offset that no real-world timezone has, so it can
+      // never coincide with the host machine's offset
+      DateTime.fromJSDate(new Date(), -3.25)
+    );
+    const date = await this.dateTimeStr.exec(this.ctx);
+    date.timezoneOffset.should.equalDecimal(-3.25);
+    date.isDateTime.should.equal(true);
+  });
+
   it("should convert '2015-01-02' to Date", async function () {
     const date = await this.dateStr.exec(this.ctx);
     date.year.should.equal(2015);

test/spec-tests/cql/CqlTypeOperatorsTest.cql

@@ -31,11 +31,9 @@ define "Convert": Tuple{
     output: null
   },
   "StringToDateTime": Tuple{
-    skipped: 'Wrong answer (different offsets)'
-    /*
     expression: convert '2014-01-01' to DateTime,
     output: @2014-01-01T
-    */  },
+  },
   "StringToTime": Tuple{
     expression: convert 'T14:30:00.0' to Time,
     output: @T14:30:00.000
@@ -79,23 +77,17 @@ define "ToConcept": Tuple{
 
 define "ToDateTime": Tuple{
   "ToDateTime1": Tuple{
-    skipped: 'Wrong answer (different offsets)'
-    /*
     expression: ToDateTime('2014-01-01'),
     output: @2014-01-01T
-    */  },
+  },
   "ToDateTime2": Tuple{
-    skipped: 'Wrong answer (different offsets)'
-    /*
     expression: ToDateTime('2014-01-01T12:05'),
     output: @2014-01-01T12:05
-    */  },
+  },
   "ToDateTime3": Tuple{
-    skipped: 'Wrong answer (different offsets)'
-    /*
     expression: ToDateTime('2014-01-01T12:05:05.955'),
     output: @2014-01-01T12:05:05.955
-    */  },
+  },
   "ToDateTime4": Tuple{
     expression: ToDateTime('2014-01-01T12:05:05.955+01:30'),
     output: @2014-01-01T12:05:05.955+01:30