diff --git a/test/built-ins/Temporal/PlainYearMonth/basic.js b/test/built-ins/Temporal/PlainYearMonth/basic.js
new file mode 100644
index 0000000000..e7fcbe6c23
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/basic.js
@@ -0,0 +1,13 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth
+description: PlainYearMonth constructor works
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const ym = new Temporal.PlainYearMonth(1976, 11);
+assert.sameValue(typeof ym, "object");
+TemporalHelpers.assertPlainYearMonth(ym, 1976, 11, "M11");
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-number.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-number.js
new file mode 100644
index 0000000000..90a720fac0
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-number.js
@@ -0,0 +1,17 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: A number argument is stringified
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainYearMonth = Temporal.PlainYearMonth.from(201906);
+TemporalHelpers.assertPlainYearMonth(plainYearMonth, 2019, 6, "M06");
+const fields = plainYearMonth.getISOFields();
+assert.sameValue(fields.calendar.id, "iso8601");
+assert.sameValue(fields.isoDay, 1, "isoDay");
+assert.sameValue(fields.isoMonth, 6, "isoMonth");
+assert.sameValue(fields.isoYear, 2019, "isoYear");
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-object.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-object.js
new file mode 100644
index 0000000000..0def1d9ffb
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-object.js
@@ -0,0 +1,47 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: An object argument
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from({ year: 2019, monthCode: "M11" }),
+  2019, 11, "M11", "Only monthCode");
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from({ year: 2019, month: 11 }),
+  2019, 11, "M11", "Only month");
+assert.throws(RangeError,
+  () => Temporal.PlainYearMonth.from({ year: 2019, month: 11, monthCode: "M12" }),
+  "Mismatch between month and monthCode");
+
+const monthDayItem = { year: 2019, month: 11, get day() { throw new Test262Error("should not read the day property") } };
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from(monthDayItem),
+  2019, 11, "M11", "month with day");
+
+const monthCodeDayItem = { year: 2019, monthCode: "M11", get day() { throw new Test262Error("should not read the day property") } };
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from(monthCodeDayItem),
+  2019, 11, "M11", "monthCode with day");
+
+assert.throws(TypeError,
+  () => Temporal.PlainYearMonth.from({}),
+  "No properties");
+assert.throws(TypeError,
+  () => Temporal.PlainYearMonth.from({ year: 2019 }),
+  "Only year");
+assert.throws(TypeError,
+  () => Temporal.PlainYearMonth.from({ year: 2019, months: 6 }),
+  "Year and plural 'months'");
+assert.throws(TypeError,
+  () => Temporal.PlainYearMonth.from({ month: 6 }),
+  "Only month");
+assert.throws(TypeError,
+  () => Temporal.PlainYearMonth.from({ monthCode: "M06" }),
+  "Only monthCode");
+assert.throws(TypeError,
+  () => Temporal.PlainYearMonth.from({ year: undefined, month: 6 }),
+  "year explicit undefined");
+
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from({ year: 1976, month: 11, months: 12 }),
+  1976, 11, "M11", "Plural property ignored");
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-plaindate.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-plaindate.js
new file mode 100644
index 0000000000..e423a148e8
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-plaindate.js
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: A PlainYearMonth argument is cloned
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const plainDate = Temporal.PlainDate.from("1976-11-18");
+const plainYearMonth = Temporal.PlainYearMonth.from(plainDate);
+TemporalHelpers.assertPlainYearMonth(plainYearMonth, 1976, 11, "M11");
+const fields = plainYearMonth.getISOFields();
+assert.sameValue(fields.calendar.id, "iso8601");
+assert.sameValue(fields.isoDay, 1, "isoDay");
+assert.sameValue(fields.isoMonth, 11, "isoMonth");
+assert.sameValue(fields.isoYear, 1976, "isoYear");
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-plainyearmonth.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-plainyearmonth.js
new file mode 100644
index 0000000000..a66b605c01
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-plainyearmonth.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: A PlainYearMonth argument is cloned
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const original = new Temporal.PlainYearMonth(2019, 11, undefined, 7);
+const result = Temporal.PlainYearMonth.from(original);
+assert.notSameValue(result, original);
+
+for (const plainYearMonth of [original, result]) {
+  TemporalHelpers.assertPlainYearMonth(plainYearMonth, 2019, 11, "M11");
+  const fields = plainYearMonth.getISOFields();
+  assert.sameValue(fields.calendar.id, "iso8601");
+  assert.sameValue(fields.isoDay, 7, "isoDay");
+  assert.sameValue(fields.isoMonth, 11, "isoMonth");
+  assert.sameValue(fields.isoYear, 2019, "isoYear");
+}
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-string-invalid.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-string-invalid.js
new file mode 100644
index 0000000000..e99fd4efe5
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-string-invalid.js
@@ -0,0 +1,11 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: An invalid ISO string is never supported
+features: [Temporal]
+---*/
+
+assert.throws(RangeError, () => Temporal.PlainYearMonth.from("2020-13", { overflow: "reject" }));
+assert.throws(RangeError, () => Temporal.PlainYearMonth.from("2020-13", { overflow: "constrain" }));
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-string-trailing-junk.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-string-trailing-junk.js
new file mode 100644
index 0000000000..b5c44677e1
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-string-trailing-junk.js
@@ -0,0 +1,10 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: RangeError thrown if a string with trailing junk is used as a PlainYearMonth
+features: [Temporal]
+---*/
+
+assert.throws(RangeError, () => Temporal.PlainYearMonth.from("1976-11junk"));
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/argument-string.js b/test/built-ins/Temporal/PlainYearMonth/from/argument-string.js
index b3a4885726..01a841c61e 100644
--- a/test/built-ins/Temporal/PlainYearMonth/from/argument-string.js
+++ b/test/built-ins/Temporal/PlainYearMonth/from/argument-string.js
@@ -8,10 +8,48 @@ includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const plainYearMonth = Temporal.PlainYearMonth.from("1970-12");
-TemporalHelpers.assertPlainYearMonth(plainYearMonth, 1970, 12, "M12");
+const inputs = [
+  "1976-11",
+  "1976-11-10",
+  "1976-11-01T09:00:00+00:00",
+  "1976-11-01T00:00:00+05:00",
+  "197611",
+  "+00197611",
+  "1976-11-18T15:23:30.1\u221202:00",
+  "1976-11-18T152330.1+00:00",
+  "19761118T15:23:30.1+00:00",
+  "1976-11-18T15:23:30.1+0000",
+  "1976-11-18T152330.1+0000",
+  "19761118T15:23:30.1+0000",
+  "19761118T152330.1+00:00",
+  "19761118T152330.1+0000",
+  "+001976-11-18T152330.1+00:00",
+  "+0019761118T15:23:30.1+00:00",
+  "+001976-11-18T15:23:30.1+0000",
+  "+001976-11-18T152330.1+0000",
+  "+0019761118T15:23:30.1+0000",
+  "+0019761118T152330.1+00:00",
+  "+0019761118T152330.1+0000",
+  "1976-11-18T15:23",
+  "1976-11-18T15",
+  "1976-11-18",
+];
+
+for (const input of inputs) {
+  const plainYearMonth = Temporal.PlainYearMonth.from(input);
+  TemporalHelpers.assertPlainYearMonth(plainYearMonth, 1976, 11, "M11");
+  const fields = plainYearMonth.getISOFields();
+  assert.sameValue(fields.calendar.id, "iso8601");
+  assert.sameValue(fields.isoDay, 1, "isoDay");
+  assert.sameValue(fields.isoMonth, 11, "isoMonth");
+  assert.sameValue(fields.isoYear, 1976, "isoYear");
+}
+
+const plainYearMonth = Temporal.PlainYearMonth.from("\u2212009999-11");
+TemporalHelpers.assertPlainYearMonth(plainYearMonth, -9999, 11, "M11");
 const fields = plainYearMonth.getISOFields();
 assert.sameValue(fields.calendar.id, "iso8601");
 assert.sameValue(fields.isoDay, 1, "isoDay");
-assert.sameValue(fields.isoMonth, 12, "isoMonth");
-assert.sameValue(fields.isoYear, 1970, "isoYear");
+assert.sameValue(fields.isoMonth, 11, "isoMonth");
+assert.sameValue(fields.isoYear, -9999, "isoYear");
+assert.sameValue(plainYearMonth.toString(), "-009999-11");
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/options-invalid.js b/test/built-ins/Temporal/PlainYearMonth/from/options-invalid.js
new file mode 100644
index 0000000000..6319d3343b
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/options-invalid.js
@@ -0,0 +1,21 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: TypeError thrown when a primitive is passed as the options argument
+features: [Temporal]
+---*/
+
+const items = [
+  { year: 2000, month: 11 },
+  "2000-11",
+  new Temporal.PlainYearMonth(2000, 11),
+];
+const values = [null, true, "hello", Symbol("foo"), 1, 1n];
+
+for (const item of items) {
+  for (const badOptions of values) {
+    assert.throws(TypeError, () => Temporal.PlainYearMonth.from(item, badOptions));
+  }
+}
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/overflow-constrain.js b/test/built-ins/Temporal/PlainYearMonth/from/overflow-constrain.js
new file mode 100644
index 0000000000..c1cacdf619
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/overflow-constrain.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: Reject value for overflow option
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const propertyBag = { year: 2000, month: 13 };
+const plainYearMonth = Temporal.PlainYearMonth.from(propertyBag, { overflow: "constrain" });
+TemporalHelpers.assertPlainYearMonth(plainYearMonth, 2000, 12, "M12", "default overflow is constrain");
+
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/overflow-invalid-string.js b/test/built-ins/Temporal/PlainYearMonth/from/overflow-invalid-string.js
index b0e4fb0931..3d5a3d8057 100644
--- a/test/built-ins/Temporal/PlainYearMonth/from/overflow-invalid-string.js
+++ b/test/built-ins/Temporal/PlainYearMonth/from/overflow-invalid-string.js
@@ -28,5 +28,7 @@ const validValues = [
   "2000-05",
 ];
 validValues.forEach((value) => {
-  assert.throws(RangeError, () => Temporal.PlainYearMonth.from(value, { overflow: "other string" }));
+  ["", "CONSTRAIN", "balance", "other string", "constra\u0131n", 3, null].forEach((overflow) => {
+    assert.throws(RangeError, () => Temporal.PlainYearMonth.from(value, { overflow }));
+  });
 });
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/overflow-reject.js b/test/built-ins/Temporal/PlainYearMonth/from/overflow-reject.js
new file mode 100644
index 0000000000..86e4151cd5
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/from/overflow-reject.js
@@ -0,0 +1,11 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: Reject value for overflow option
+features: [Temporal]
+---*/
+
+const bad = { year: 2019, month: 13 };
+assert.throws(RangeError, () => Temporal.PlainYearMonth.from(bad, { overflow: "reject" }));
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/overflow-undefined.js b/test/built-ins/Temporal/PlainYearMonth/from/overflow-undefined.js
index 1d906e3c27..c085b384b6 100644
--- a/test/built-ins/Temporal/PlainYearMonth/from/overflow-undefined.js
+++ b/test/built-ins/Temporal/PlainYearMonth/from/overflow-undefined.js
@@ -32,6 +32,8 @@ validValues.forEach((value) => {
   TemporalHelpers.assertPlainYearMonth(explicit, 2000, 5, "M05", "overflow is ignored");
   const implicit = Temporal.PlainYearMonth.from(value, {});
   TemporalHelpers.assertPlainYearMonth(implicit, 2000, 5, "M05", "overflow is ignored");
+  const lambda = Temporal.PlainYearMonth.from(value, () => {});
+  TemporalHelpers.assertPlainYearMonth(lambda, 2000, 5, "M05", "overflow is ignored");
 });
 
 const propertyBag = { year: 2000, month: 13 };
@@ -39,3 +41,5 @@ const explicit = Temporal.PlainYearMonth.from(propertyBag, { overflow: undefined
 TemporalHelpers.assertPlainYearMonth(explicit, 2000, 12, "M12", "default overflow is constrain");
 const implicit = Temporal.PlainYearMonth.from(propertyBag, {});
 TemporalHelpers.assertPlainYearMonth(implicit, 2000, 12, "M12", "default overflow is constrain");
+const lambda = Temporal.PlainYearMonth.from(propertyBag, () => {});
+TemporalHelpers.assertPlainYearMonth(lambda, 2000, 12, "M12", "default overflow is constrain");
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/daysInMonth/basic.js b/test/built-ins/Temporal/PlainYearMonth/prototype/daysInMonth/basic.js
new file mode 100644
index 0000000000..94883e5868
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/daysInMonth/basic.js
@@ -0,0 +1,11 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plainyearmonth.prototype.daysinmonth
+description: daysInMonth works
+features: [Temporal]
+---*/
+
+const ym = new Temporal.PlainYearMonth(1976, 11);
+assert.sameValue(ym.daysInMonth, 30);
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/daysInYear/basic.js b/test/built-ins/Temporal/PlainYearMonth/prototype/daysInYear/basic.js
new file mode 100644
index 0000000000..f17cde06c5
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/daysInYear/basic.js
@@ -0,0 +1,11 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plainyearmonth.prototype.daysinyear
+description: daysInYear works
+features: [Temporal]
+---*/
+
+const ym = new Temporal.PlainYearMonth(1976, 11);
+assert.sameValue(ym.daysInYear, 366);
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/monthsInYear/basic.js b/test/built-ins/Temporal/PlainYearMonth/prototype/monthsInYear/basic.js
new file mode 100644
index 0000000000..8a2bfbc71e
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/monthsInYear/basic.js
@@ -0,0 +1,11 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.plainyearmonth.prototype.monthsinyear
+description: monthsInYear works
+features: [Temporal]
+---*/
+
+const ym = new Temporal.PlainYearMonth(1976, 11);
+assert.sameValue(ym.monthsInYear, 12);
diff --git a/test/intl402/Temporal/PlainYearMonth/from/argument-object.js b/test/intl402/Temporal/PlainYearMonth/from/argument-object.js
new file mode 100644
index 0000000000..5e0bd6f11b
--- /dev/null
+++ b/test/intl402/Temporal/PlainYearMonth/from/argument-object.js
@@ -0,0 +1,17 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.from
+description: An object argument
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const monthDayItem = { calendar: "gregory", era: "ce", eraYear: 2019, month: 11, get day() { throw new Test262Error("should not read the day property") } };
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from(monthDayItem),
+  2019, 11, "M11", "month with day", "ce", 2019);
+
+const monthCodeDayItem = { calendar: "gregory", era: "ce", eraYear: 2019, monthCode: "M11", get day() { throw new Test262Error("should not read the day property") } };
+TemporalHelpers.assertPlainYearMonth(Temporal.PlainYearMonth.from(monthCodeDayItem),
+  2019, 11, "M11", "monthCode with day", "ce", 2019);