diff --git a/lib/internal/test_runner/reporter/tap.js b/lib/internal/test_runner/reporter/tap.js
index cd0bbe8ca53003..ed8c3f836d4694 100644
--- a/lib/internal/test_runner/reporter/tap.js
+++ b/lib/internal/test_runner/reporter/tap.js
@@ -3,6 +3,7 @@ const {
   ArrayPrototypeForEach,
   ArrayPrototypeJoin,
   ArrayPrototypePush,
+  DatePrototypeToISOString,
   ObjectEntries,
   RegExpPrototypeSymbolReplace,
   RegExpPrototypeSymbolSplit,
@@ -125,24 +126,28 @@ function tapEscape(input) {
 }
 
 function jsToYaml(indent, name, value, seen) {
-  if (value === null || value === undefined) {
+  if (value === undefined) {
     return '';
   }
 
-  if (typeof value !== 'object') {
-    const prefix = `${indent}  ${name}: `;
+  const prefix = `${indent}  ${name}:`;
+
+  if (value === null) {
+    return `${prefix} ~\n`;
+  }
 
+  if (typeof value !== 'object') {
     if (typeof value !== 'string') {
-      return `${prefix}${inspectWithNoCustomRetry(value, inspectOptions)}\n`;
+      return `${prefix} ${inspectWithNoCustomRetry(value, inspectOptions)}\n`;
     }
 
     const lines = RegExpPrototypeSymbolSplit(kLineBreakRegExp, value);
 
     if (lines.length === 1) {
-      return `${prefix}${inspectWithNoCustomRetry(value, inspectOptions)}\n`;
+      return `${prefix} ${inspectWithNoCustomRetry(value, inspectOptions)}\n`;
     }
 
-    let str = `${prefix}|-\n`;
+    let str = `${prefix} |-\n`;
 
     for (let i = 0; i < lines.length; i++) {
       str += `${indent}    ${lines[i]}\n`;
@@ -154,11 +159,16 @@ function jsToYaml(indent, name, value, seen) {
   seen.add(value);
   const entries = ObjectEntries(value);
   const isErrorObj = isError(value);
-  let result = '';
   let propsIndent = indent;
+  let result = '';
 
   if (name != null) {
-    result += `${indent}  ${name}:\n`;
+    result += prefix;
+    if (internalBinding('types').isDate(value)) {
+      // YAML uses the ISO-8601 standard to express dates.
+      result += ' ' + DatePrototypeToISOString(value);
+    }
+    result += '\n';
     propsIndent += '  ';
   }
 
diff --git a/test/fixtures/test-runner/output/junit_reporter.snapshot b/test/fixtures/test-runner/output/junit_reporter.snapshot
index 94d16f7205a71a..c7136d18e6c3df 100644
--- a/test/fixtures/test-runner/output/junit_reporter.snapshot
+++ b/test/fixtures/test-runner/output/junit_reporter.snapshot
@@ -422,12 +422,19 @@ Error [ERR_TEST_FAILURE]: bar
 }
 		</failure>
 	</testcase>
-	<testcase name="assertion errors display actual and expected properly" time="*" classname="test" failure="Expected values to be loosely deep-equal:{  bar: 1,  boo: [    1  ],  foo: 1}should loosely deep-equal{  boo: [    1  ],  circular: &lt;ref *1> {    bar: 2,    c: [Circular *1]  }}">
-		<failure type="testCodeFailure" message="Expected values to be loosely deep-equal:{  bar: 1,  boo: [    1  ],  foo: 1}should loosely deep-equal{  boo: [    1  ],  circular: &lt;ref *1> {    bar: 2,    c: [Circular *1]  }}">
+	<testcase name="assertion errors display actual and expected properly" time="*" classname="test" failure="Expected values to be loosely deep-equal:{  bar: 1,  baz: {    date: 1970-01-01T00:00:00.000Z,    null: null,    number: 1,    string: 'Hello',    undefined: undefined  },  boo: [    1  ],  foo: 1}should loosely deep-equal{  baz: {    date: 1970-01-01T00:00:00.000Z,    null: null,    number: 1,    string: 'Hello',    undefined: undefined  },  boo: [    1  ],  circular: &lt;ref *1> {    bar: 2,    c: [Circular *1]  }}">
+		<failure type="testCodeFailure" message="Expected values to be loosely deep-equal:{  bar: 1,  baz: {    date: 1970-01-01T00:00:00.000Z,    null: null,    number: 1,    string: 'Hello',    undefined: undefined  },  boo: [    1  ],  foo: 1}should loosely deep-equal{  baz: {    date: 1970-01-01T00:00:00.000Z,    null: null,    number: 1,    string: 'Hello',    undefined: undefined  },  boo: [    1  ],  circular: &lt;ref *1> {    bar: 2,    c: [Circular *1]  }}">
 [Error [ERR_TEST_FAILURE]: Expected values to be loosely deep-equal:
 
 {
   bar: 1,
+  baz: {
+    date: 1970-01-01T00:00:00.000Z,
+    null: null,
+    number: 1,
+    string: 'Hello',
+    undefined: undefined
+  },
   boo: [
     1
   ],
@@ -437,6 +444,13 @@ Error [ERR_TEST_FAILURE]: bar
 should loosely deep-equal
 
 {
+  baz: {
+    date: 1970-01-01T00:00:00.000Z,
+    null: null,
+    number: 1,
+    string: 'Hello',
+    undefined: undefined
+  },
   boo: [
     1
   ],
@@ -451,6 +465,13 @@ should loosely deep-equal
   
   {
     bar: 1,
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -460,6 +481,13 @@ should loosely deep-equal
   should loosely deep-equal
   
   {
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
diff --git a/test/fixtures/test-runner/output/lcov_reporter.snapshot b/test/fixtures/test-runner/output/lcov_reporter.snapshot
index 7146a369275980..11b2bc10394cb9 100644
--- a/test/fixtures/test-runner/output/lcov_reporter.snapshot
+++ b/test/fixtures/test-runner/output/lcov_reporter.snapshot
@@ -695,6 +695,13 @@ DA:389,1
 DA:390,1
 DA:391,1
 DA:392,1
-LH:390
-LF:392
+DA:393,1
+DA:394,1
+DA:395,1
+DA:396,1
+DA:397,1
+DA:398,1
+DA:399,1
+LH:397
+LF:399
 end_of_record
diff --git a/test/fixtures/test-runner/output/output.js b/test/fixtures/test-runner/output/output.js
index 95512e745fccaa..1557b4da4ee7d9 100644
--- a/test/fixtures/test-runner/output/output.js
+++ b/test/fixtures/test-runner/output/output.js
@@ -383,8 +383,15 @@ test('assertion errors display actual and expected properly', async () => {
   const tmpLimit = Error.stackTraceLimit;
   Error.stackTraceLimit = 1;
   const boo = [1];
+  const baz = {
+    date: new Date(0),
+    null: null,
+    number: 1,
+    string: 'Hello',
+    undefined: undefined,
+  }
   try {
-    assert.deepEqual({ foo: 1, bar: 1, boo }, { boo, circular }); // eslint-disable-line no-restricted-properties
+    assert.deepEqual({ foo: 1, bar: 1, boo, baz }, { boo, baz, circular }); // eslint-disable-line no-restricted-properties
   } catch (err) {
     Error.stackTraceLimit = tmpLimit;
     throw err;
diff --git a/test/fixtures/test-runner/output/output.snapshot b/test/fixtures/test-runner/output/output.snapshot
index dfa8b3f2df2b7a..0e6cab8549d4b2 100644
--- a/test/fixtures/test-runner/output/output.snapshot
+++ b/test/fixtures/test-runner/output/output.snapshot
@@ -643,6 +643,13 @@ not ok 61 - assertion errors display actual and expected properly
     
     {
       bar: 1,
+      baz: {
+        date: 1970-01-01T00:00:00.000Z,
+        null: null,
+        number: 1,
+        string: 'Hello',
+        undefined: undefined
+      },
       boo: [
         1
       ],
@@ -652,6 +659,13 @@ not ok 61 - assertion errors display actual and expected properly
     should loosely deep-equal
     
     {
+      baz: {
+        date: 1970-01-01T00:00:00.000Z,
+        null: null,
+        number: 1,
+        string: 'Hello',
+        undefined: undefined
+      },
       boo: [
         1
       ],
@@ -665,6 +679,11 @@ not ok 61 - assertion errors display actual and expected properly
   expected:
     boo:
       0: 1
+    baz:
+      date: 1970-01-01T00:00:00.000Z
+      null: ~
+      number: 1
+      string: 'Hello'
     circular:
       bar: 2
       c: <Circular>
@@ -673,6 +692,11 @@ not ok 61 - assertion errors display actual and expected properly
     bar: 1
     boo:
       0: 1
+    baz:
+      date: 1970-01-01T00:00:00.000Z
+      null: ~
+      number: 1
+      string: 'Hello'
   operator: 'deepEqual'
   stack: |-
     *
diff --git a/test/fixtures/test-runner/output/output_cli.snapshot b/test/fixtures/test-runner/output/output_cli.snapshot
index 3bfa8cee4bf2a1..cd2be499a3b7de 100644
--- a/test/fixtures/test-runner/output/output_cli.snapshot
+++ b/test/fixtures/test-runner/output/output_cli.snapshot
@@ -643,6 +643,13 @@ not ok 61 - assertion errors display actual and expected properly
     
     {
       bar: 1,
+      baz: {
+        date: 1970-01-01T00:00:00.000Z,
+        null: null,
+        number: 1,
+        string: 'Hello',
+        undefined: undefined
+      },
       boo: [
         1
       ],
@@ -652,6 +659,13 @@ not ok 61 - assertion errors display actual and expected properly
     should loosely deep-equal
     
     {
+      baz: {
+        date: 1970-01-01T00:00:00.000Z,
+        null: null,
+        number: 1,
+        string: 'Hello',
+        undefined: undefined
+      },
       boo: [
         1
       ],
@@ -665,6 +679,11 @@ not ok 61 - assertion errors display actual and expected properly
   expected:
     boo:
       0: 1
+    baz:
+      date: 1970-01-01T00:00:00.000Z
+      null: ~
+      number: 1
+      string: 'Hello'
     circular:
       bar: 2
       c: <Circular>
@@ -673,6 +692,11 @@ not ok 61 - assertion errors display actual and expected properly
     bar: 1
     boo:
       0: 1
+    baz:
+      date: 1970-01-01T00:00:00.000Z
+      null: ~
+      number: 1
+      string: 'Hello'
   operator: 'deepEqual'
   stack: |-
     *
diff --git a/test/fixtures/test-runner/output/spec_reporter.snapshot b/test/fixtures/test-runner/output/spec_reporter.snapshot
index bfa5b61ac00137..5af5f4750569bc 100644
--- a/test/fixtures/test-runner/output/spec_reporter.snapshot
+++ b/test/fixtures/test-runner/output/spec_reporter.snapshot
@@ -263,6 +263,13 @@
   
   {
     bar: 1,
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -272,6 +279,13 @@
   should loosely deep-equal
   
   {
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -536,6 +550,13 @@
   
   {
     bar: 1,
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -545,6 +566,13 @@
   should loosely deep-equal
   
   {
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
diff --git a/test/fixtures/test-runner/output/spec_reporter_cli.snapshot b/test/fixtures/test-runner/output/spec_reporter_cli.snapshot
index 933385e1e02161..1321cb7321400d 100644
--- a/test/fixtures/test-runner/output/spec_reporter_cli.snapshot
+++ b/test/fixtures/test-runner/output/spec_reporter_cli.snapshot
@@ -263,6 +263,13 @@
   
   {
     bar: 1,
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -272,6 +279,13 @@
   should loosely deep-equal
   
   {
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -283,8 +297,8 @@
       * {
     generatedMessage: true,
     code: 'ERR_ASSERTION',
-    actual: { foo: 1, bar: 1, boo: [ 1 ] },
-    expected: { boo: [ 1 ], circular: <ref *1> { bar: 2, c: [Circular *1] } },
+    actual: { foo: 1, bar: 1, boo: [ 1 ], baz: { date: 1970-01-01T00:00:00.000Z, null: null, number: 1, string: 'Hello', undefined: undefined } },
+    expected: { boo: [ 1 ], baz: { date: 1970-01-01T00:00:00.000Z, null: null, number: 1, string: 'Hello', undefined: undefined }, circular: <ref *1> { bar: 2, c: [Circular *1] } },
     operator: 'deepEqual'
   }
 
@@ -536,6 +550,13 @@
   
   {
     bar: 1,
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -545,6 +566,13 @@
   should loosely deep-equal
   
   {
+    baz: {
+      date: 1970-01-01T00:00:00.000Z,
+      null: null,
+      number: 1,
+      string: 'Hello',
+      undefined: undefined
+    },
     boo: [
       1
     ],
@@ -556,8 +584,8 @@
       * {
     generatedMessage: true,
     code: 'ERR_ASSERTION',
-    actual: { foo: 1, bar: 1, boo: [ 1 ] },
-    expected: { boo: [ 1 ], circular: <ref *1> { bar: 2, c: [Circular *1] } },
+    actual: { foo: 1, bar: 1, boo: [ 1 ], baz: { date: 1970-01-01T00:00:00.000Z, null: null, number: 1, string: 'Hello', undefined: undefined } },
+    expected: { boo: [ 1 ], baz: { date: 1970-01-01T00:00:00.000Z, null: null, number: 1, string: 'Hello', undefined: undefined }, circular: <ref *1> { bar: 2, c: [Circular *1] } },
     operator: 'deepEqual'
   }