From 355cfe67c0ff50a6e179ebd2b4f3d7dd40f6d966 Mon Sep 17 00:00:00 2001
From: Michael Whatcott <mike@smarty.com>
Date: Fri, 6 Oct 2023 10:04:46 -0600
Subject: [PATCH] Assertions whose output begins with "<<FATAL>>" end tests
 immediately.

...via `*testing.T.Fatalf`.
---
 fixture.go      | 10 +++++++---
 fixture_test.go | 38 +++++++++++++++++++++++++++++++++++---
 2 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/fixture.go b/fixture.go
index e628347..97fd7b0 100644
--- a/fixture.go
+++ b/fixture.go
@@ -60,13 +60,17 @@ func (this *Fixture) Run(name string, test func(fixture *Fixture)) {
 // So is a convenience method for reporting assertion failure messages,
 // from the many assertion functions found in github.com/smarty/assertions/should.
 // Example: this.So(actual, should.Equal, expected)
+// Example: this.So(actual, must.Equal, expected) // ends test IMMEDIATELY in case of failure
 func (this *Fixture) So(actual any, assert assertion, expected ...any) bool {
+	const fatalPrefix = "<<FATAL>>"
 	failure := assert(actual, expected...)
-	failed := len(failure) > 0
-	if failed {
+	if strings.HasPrefix(failure, fatalPrefix) {
+		failure = strings.TrimPrefix(failure, fatalPrefix)
+		this.t.Fatalf(reports.FailureReport(failure, reports.StackTrace()))
+	} else if len(failure) > 0 {
 		this.fail(failure)
 	}
-	return !failed
+	return len(failure) == 0
 }
 
 // Assert tests a boolean which, if not true, marks the current test case as failed and
diff --git a/fixture_test.go b/fixture_test.go
index b92110c..49b46a4 100644
--- a/fixture_test.go
+++ b/fixture_test.go
@@ -76,6 +76,29 @@ func TestSoFailsAndLogs(t *testing.T) {
 	}
 }
 
+func TestSoFatal(t *testing.T) {
+	t.Parallel()
+
+	test := Setup(false)
+
+	result := test.fixture.So(true, MustBeFalse)
+	test.fixture.finalize()
+
+	if result {
+		t.Error("Expected false result, got true")
+	}
+	output := strings.TrimSpace(test.out.String())
+	if !strings.Contains(output, "Expected false, got true instead") {
+		t.Errorf("Unexpected output: [%s]", test.out.String())
+	}
+	if strings.Contains(output, "<<FATAL>>") {
+		t.Errorf("Unexpected internal prefix should have been trimmed.")
+	}
+	if !test.fakeT.fatal {
+		t.Error("Test should have been marked as fatal.")
+	}
+}
+
 func TestAssertPasses(t *testing.T) {
 	t.Parallel()
 
@@ -385,6 +408,7 @@ func Setup(verbose bool) *FixtureTestState {
 type FakeTestingT struct {
 	log    *bytes.Buffer
 	failed bool
+	fatal  bool
 }
 
 func (self *FakeTestingT) Helper()                           {}
@@ -394,22 +418,30 @@ func (self *FakeTestingT) Fail()                             { self.failed = tru
 func (self *FakeTestingT) Failed() bool                      { return self.failed }
 func (this *FakeTestingT) Errorf(format string, args ...any) {}
 func (this *FakeTestingT) Fatalf(format string, args ...any) {
-	this.Fail()
+	this.fatal = true
 	this.Log(fmt.Sprintf(format, args...))
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
-func ShouldBeTrue(actual any, expected ...any) string {
+func ShouldBeTrue(actual any, _ ...any) string {
 	if actual != true {
 		return "Expected true, got false instead"
 	}
 	return ""
 }
 
-func ShouldBeFalse(actual any, expected ...any) string {
+func ShouldBeFalse(actual any, _ ...any) string {
 	if actual == true {
 		return "Expected false, got true instead"
 	}
 	return ""
 }
+
+func MustBeFalse(actual any, _ ...any) string {
+	result := ShouldBeFalse(actual)
+	if len(result) > 0 {
+		return "<<FATAL>>" + result
+	}
+	return ""
+}