diff --git a/vlib/v/preludes/test_runner_teamcity.v b/vlib/v/preludes/test_runner_teamcity.v
index f801991740..5231d986ac 100644
--- a/vlib/v/preludes/test_runner_teamcity.v
+++ b/vlib/v/preludes/test_runner_teamcity.v
@@ -1,6 +1,7 @@
 module main
 
 import time
+import term
 
 // Provide a Teamcity implementation of the TestRunner interface.
 // Used in Teamcity and JetBrains IDEs for nice test reporting.
@@ -20,6 +21,7 @@ mut:
 	fn_passes        u64
 	fn_fails         u64
 
+	assertion_info      VAssertMetaInfo
 	total_assert_passes u64
 	total_assert_fails  u64
 }
@@ -58,8 +60,15 @@ fn (mut runner TeamcityTestRunner) fn_start() bool {
 	runner.fn_assert_passes = 0
 	runner.start_time = time.now()
 	runner.fname = normalise_fname(runner.fn_test_info.name)
-	println("Start '${runner.fname}'")
-	eprintln("##teamcity[testStarted name='${runner.fname}' locationHint='v_qn://${runner.file_test_info.file}:${runner.fname}']")
+
+	msg := "Start '${runner.fname}' test"
+	println(term.gray(msg))
+
+	runner.print_service("
+		|##teamcity[
+		|testStarted name='${runner.fname}'
+		|locationHint='v_qn://${runner.file_test_info.file}:${runner.fname}'
+		|]".strip_margin())
 	return true
 }
 
@@ -67,16 +76,78 @@ fn (mut runner TeamcityTestRunner) fn_pass() {
 	runner.fn_passes++
 	duration := runner.test_duration()
 	eprintln("##teamcity[testFinished name='${runner.fname}' duration='${duration}']")
+	end_msg := "Finish '${runner.fname}' test"
+	println(term.gray(end_msg))
+	msg := "Test '${runner.fname}' passed"
+	println(term.green(msg))
 	println('\n')
 }
 
 fn (mut runner TeamcityTestRunner) fn_fail() {
 	runner.fn_fails++
 	duration := runner.test_duration()
-	eprintln("##teamcity[testFailed name='${runner.fname}' duration='${duration}' message='assertion failed']")
+	assertion := runner.assertion_info
+
+	mut actual := runner.prepare_value(assertion.lvalue)
+	mut expected := runner.prepare_value(assertion.rvalue)
+
+	message := if assertion.has_msg {
+		'Assertion "${assertion.message}" failed'
+	} else {
+		op := if assertion.op == '' { '' } else { assertion.op }
+
+		if op == 'in' {
+			parts := assertion.src.split('in')
+			if parts.len == 2 {
+				left := parts[0].trim(' ')
+				right := parts[1].trim(' ')
+				'Assertion that "${left}" in "${right}" failed'
+			} else {
+				'Assertion "${assertion.src}" failed'
+			}
+		} else if op == 'is' {
+			'Assertion that left and right type are equal failed'
+		} else if op == 'call' {
+			actual = 'false'
+			expected = 'true'
+			'Assertion that function call "${assertion.src}" returns true failed'
+		} else {
+			lines := assertion.src.split_into_lines()
+			if lines.len == 1 {
+				'Assertion "${lines.first()}" failed'
+			} else {
+				'Assertion failed'
+			}
+		}
+	}
+
+	details := 'See failed assertion: ${assertion.fpath}:${assertion.line_nr + 1}'
+
+	runner.print_service("
+		 |##teamcity[
+		 |testFailed name='${runner.fname}'
+		 |duration='${duration}'
+		 |details='${details}'
+		 |type='comparisonFailure'
+		 |actual='${actual}'
+		 |expected='${expected}'
+		 |message='${message}'
+		 |]".strip_margin())
 	println('\n')
 }
 
+// prepare_value escapes the value for Teamcity output.
+// For example, it replaces `\n` with `|n`, otherwise Teamcity
+// will not correctly parse the output.
+fn (mut _ TeamcityTestRunner) prepare_value(raw string) string {
+	return raw
+		.replace('\n', '|n')
+		.replace('\r', '|r')
+		.replace('[', '|[')
+		.replace(']', '|]')
+		.replace("'", "|'")
+}
+
 fn (mut runner TeamcityTestRunner) fn_error(line_nr int, file string, mod string, fn_name string, errmsg string) {
 	eprintln('>>> TeamcityTestRunner fn_error ${runner.fname}, line_nr: ${line_nr}, file: ${file}, mod: ${mod}, fn_name: ${fn_name}, errmsg: ${errmsg}')
 }
@@ -85,6 +156,15 @@ fn (mut runner TeamcityTestRunner) test_duration() i64 {
 	return time.now().unix_time_milli() - runner.start_time.unix_time_milli()
 }
 
+// print_service prepare and prints a Teamcity service message.
+fn (mut runner TeamcityTestRunner) print_service(msg string) {
+	without_new_lines := msg
+		.trim('\n\r ')
+		.replace('\r', '')
+		.replace('\n', ' ')
+	eprintln(without_new_lines)
+}
+
 //
 
 fn (mut runner TeamcityTestRunner) assert_pass(i &VAssertMetaInfo) {
@@ -92,45 +172,13 @@ fn (mut runner TeamcityTestRunner) assert_pass(i &VAssertMetaInfo) {
 	runner.fn_assert_passes++
 
 	filepath := i.fpath.clone()
-	println('>>> assert_pass ${filepath}:${i.line_nr + 1}')
+	msg := '>>> assertion passed ${filepath}:${i.line_nr + 1}'
+	println(term.green(msg))
 
 	unsafe { i.free() }
 }
 
 fn (mut runner TeamcityTestRunner) assert_fail(i &VAssertMetaInfo) {
 	runner.total_assert_fails++
-
-	filepath := i.fpath.clone()
-	mut final_filepath := filepath + ':${i.line_nr + 1}:'
-	mut final_funcname := 'fn ' + i.fn_name.replace('main.', '').replace('__', '.')
-	final_src := 'assert ' + i.src
-	eprintln('${final_filepath} ${final_funcname}')
-	if i.op.len > 0 && i.op != 'call' {
-		mut lvtitle := '    Left value:'
-		mut rvtitle := '    Right value:'
-		mut slvalue := '${i.lvalue}'
-		mut srvalue := '${i.rvalue}'
-		cutoff_limit := 30
-		if slvalue.len > cutoff_limit || srvalue.len > cutoff_limit {
-			eprintln('  > ${final_src}')
-			eprintln(lvtitle)
-			eprintln('      ${slvalue}')
-			eprintln(rvtitle)
-			eprintln('      ${srvalue}')
-		} else {
-			eprintln('   > ${final_src}')
-			eprintln(' ${lvtitle} ${slvalue}')
-			eprintln('${rvtitle} ${srvalue}')
-		}
-	} else {
-		eprintln('    ${final_src}')
-	}
-	if i.has_msg {
-		mut mtitle := '        Message:'
-		mut mvalue := '${i.message}'
-		eprintln('${mtitle} ${mvalue}')
-	}
-	eprintln('')
-
-	unsafe { i.free() }
+	runner.assertion_info = *i
 }