diff --git a/config.go b/config.go
index 3d8b295..2800c1d 100644
--- a/config.go
+++ b/config.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"math"
 	"strings"
+	"unicode/utf8"
 )
 
 const (
@@ -37,25 +38,35 @@ type failure[T any] struct {
 // String implements [fmt.Stringer] for failure, allowing it to print itself in the test log.
 func (f failure[T]) String() string {
 	s := &strings.Builder{}
-	s.WriteByte('\n')
-
-	s.WriteString(f.cfg.title)
-	s.WriteByte('\n')
-	s.WriteString(strings.Repeat("-", len(f.cfg.title)))
-	s.WriteString("\n\n")
+	f.cfg.writeHeader(s)
 
 	fmt.Fprintf(s, "Got:\t%+v\n", f.got)
 	fmt.Fprintf(s, "Wanted:\t%+v\n", f.want)
 
-	if f.cfg.context != "" {
-		fmt.Fprintf(s, "\n(%s)\n", f.cfg.context)
-	}
+	f.cfg.writeFooter(s)
+
+	return s.String()
+}
 
-	if f.cfg.reason != "" {
-		fmt.Fprintf(s, "\nBecause: %s\n", f.cfg.reason)
+// writeHeader writes the title block (leading blank line, title, underline, blank line)
+// to s. The underline is sized by rune count so multi-byte titles align correctly.
+func (c config) writeHeader(s *strings.Builder) {
+	s.WriteByte('\n')
+	s.WriteString(c.title)
+	s.WriteByte('\n')
+	s.WriteString(strings.Repeat("-", utf8.RuneCountInString(c.title)))
+	s.WriteString("\n\n")
+}
+
+// writeFooter writes any optional context and reason lines to s.
+func (c config) writeFooter(s *strings.Builder) {
+	if c.context != "" {
+		fmt.Fprintf(s, "\n(%s)\n", c.context)
 	}
 
-	return s.String()
+	if c.reason != "" {
+		fmt.Fprintf(s, "\nBecause: %s\n", c.reason)
+	}
 }
 
 // Option is a configuration option for a test.
@@ -79,7 +90,7 @@ func (o option) apply(cfg *config) error {
 // two floating point numbers before they are considered equal. This setting is only
 // used in [NearlyEqual] and [NotNearlyEqual].
 //
-// Setting threshold to ±math.Inf is an error and will fail the test.
+// Setting threshold to ±[math.Inf] is an error and will fail the test.
 //
 // The default is 1e-8, a sensible default for most cases.
 func FloatEqualityThreshold(threshold float64) Option {
@@ -137,12 +148,12 @@ func Title(title string) Option {
 //	test.Ok(t, err, test.Context("something complicated failed"))
 func Context(format string, args ...any) Option {
 	f := func(cfg *config) error {
-		if format == "" {
+		context := strings.TrimSpace(fmt.Sprintf(format, args...))
+		if context == "" {
 			return errors.New("cannot set context to an empty string")
 		}
 
-		context := fmt.Sprintf(format, args...)
-		cfg.context = strings.TrimSpace(context)
+		cfg.context = context
 
 		return nil
 	}
diff --git a/test.go b/test.go
index 446b899..7e3122d 100644
--- a/test.go
+++ b/test.go
@@ -11,7 +11,7 @@ import (
 	"io"
 	"math"
 	"os"
-	"sync"
+	"strings"
 	"testing"
 
 	"go.followtheprocess.codes/diff"
@@ -19,6 +19,11 @@ import (
 	"go.followtheprocess.codes/hue"
 )
 
+// errAny is a sentinel rendered in failure output when the caller expected
+// an error but got nil — it reads more naturally than the previous
+// placeholder errors.New("error") (which printed "Wanted: error").
+var errAny = errors.New("<any error>")
+
 // ColorEnabled sets whether the output from this package is colourised.
 //
 // test defaults to automatic detection based on a number of attributes:
@@ -125,7 +130,7 @@ func EqualFunc[T any](tb testing.TB, got, want T, equal func(a, b T) bool, optio
 	}
 }
 
-// NotEqualFunc is like [Equal] but accepts a custom comparator function, useful
+// NotEqualFunc is like [NotEqual] but accepts a custom comparator function, useful
 // when the items to be compared do not implement the comparable generic constraint.
 //
 // The signature of the comparator is such that standard library functions such as
@@ -133,8 +138,8 @@ func EqualFunc[T any](tb testing.TB, got, want T, equal func(a, b T) bool, optio
 //
 // The comparator should return true if the two items should be considered equal.
 //
-//	test.EqualFunc(t, []int{1, 2, 3}, []int{1, 2, 3}, slices.Equal) // Fails
-//	test.EqualFunc(t, []int{1, 2, 3}, []int{4, 5, 6}, slices.Equal) // Passes
+//	test.NotEqualFunc(t, []int{1, 2, 3}, []int{1, 2, 3}, slices.Equal) // Fails
+//	test.NotEqualFunc(t, []int{1, 2, 3}, []int{4, 5, 6}, slices.Equal) // Passes
 func NotEqualFunc[T any](tb testing.TB, got, want T, equal func(a, b T) bool, options ...Option) {
 	tb.Helper()
 
@@ -181,13 +186,53 @@ func NearlyEqual[T ~float32 | ~float64](tb testing.TB, got, want T, options ...O
 		}
 	}
 
-	diff := math.Abs(float64(got - want))
-	if diff > cfg.floatEqualityThreshold {
+	delta := math.Abs(float64(got - want))
+	if delta > cfg.floatEqualityThreshold {
 		cfg.reason = fmt.Sprintf(
 			"Difference %v - %v = %v exceeds maximum tolerance of %v",
 			got,
 			want,
-			diff,
+			delta,
+			cfg.floatEqualityThreshold,
+		)
+		fail := failure[T]{
+			got:  got,
+			want: want,
+			cfg:  cfg,
+		}
+		tb.Fatal(fail.String())
+	}
+}
+
+// NotNearlyEqual is the opposite of [NearlyEqual]. It fails when got and want
+// are within the float equality threshold of each other.
+//
+// The threshold defaults to 1e-8 and can be configured with the
+// [FloatEqualityThreshold] option.
+//
+//	test.NotNearlyEqual(t, 3.0000001, 3.0) // Passes, different enough
+//	test.NotNearlyEqual(t, 3.0000000001, 3.0) // Fails, too close to be considered different
+func NotNearlyEqual[T ~float32 | ~float64](tb testing.TB, got, want T, options ...Option) {
+	tb.Helper()
+
+	cfg := defaultConfig()
+	cfg.title = "NearlyEqual"
+
+	for _, option := range options {
+		if err := option.apply(&cfg); err != nil {
+			tb.Fatalf("NotNearlyEqual: could not apply options: %v", err)
+
+			return
+		}
+	}
+
+	delta := math.Abs(float64(got - want))
+	if delta <= cfg.floatEqualityThreshold {
+		cfg.reason = fmt.Sprintf(
+			"Difference %v - %v = %v is within tolerance of %v",
+			got,
+			want,
+			delta,
 			cfg.floatEqualityThreshold,
 		)
 		fail := failure[T]{
@@ -248,7 +293,7 @@ func Err(tb testing.TB, err error, options ...Option) {
 	if err == nil {
 		fail := failure[error]{
 			got:  nil,
-			want: errors.New("error"),
+			want: errAny,
 			cfg:  cfg,
 		}
 		tb.Fatal(fail.String())
@@ -287,7 +332,7 @@ func WantErr(tb testing.TB, err error, want bool, options ...Option) {
 
 		if want {
 			reason = fmt.Sprintf("Wanted an error but got %v", err)
-			wanted = errors.New("error")
+			wanted = errAny
 		} else {
 			reason = fmt.Sprintf("Got an unexpected error: %v", err)
 			wanted = nil
@@ -364,9 +409,9 @@ func False(tb testing.TB, got bool, options ...Option) {
 //
 // If either got or want do not end in a newline, one is added to avoid a
 // "No newline at end of file" warning in the diff which is visually distracting.
-func Diff(tb testing.TB, got, want string) {
+func Diff(tb testing.TB, got, want string, options ...Option) {
 	tb.Helper()
-	DiffBytes(tb, []byte(got), []byte(want))
+	DiffBytes(tb, []byte(got), []byte(want), options...)
 }
 
 // DiffBytes fails if the two []byte got and want are not equal and provides a rich
@@ -374,16 +419,31 @@ func Diff(tb testing.TB, got, want string) {
 //
 // If either got or want do not end in a newline, one is added to avoid a
 // "No newline at end of file" warning in the diff which is visually distracting.
-func DiffBytes(tb testing.TB, got, want []byte) {
+func DiffBytes(tb testing.TB, got, want []byte, options ...Option) {
 	tb.Helper()
 
+	cfg := defaultConfig()
+	cfg.title = "Diff"
+
+	for _, option := range options {
+		if err := option.apply(&cfg); err != nil {
+			tb.Fatalf("DiffBytes: could not apply options: %v", err)
+
+			return
+		}
+	}
+
 	got = fixNL(got)
 	want = fixNL(want)
 
 	d := diff.New("want", want, "got", got)
 
 	if !d.Equal() {
-		tb.Fatalf("\nDiff\n----\n%s\n", render.Render(d))
+		s := &strings.Builder{}
+		cfg.writeHeader(s)
+		s.Write(render.Render(d))
+		cfg.writeFooter(s)
+		tb.Fatal(s.String())
 	}
 }
 
@@ -392,20 +452,20 @@ func DiffBytes(tb testing.TB, got, want []byte) {
 //
 // If either got or want do not end in a newline, one is added to avoid
 // a "No newline at end of file" warning in the diff which is visually distracting.
-func DiffReader(tb testing.TB, got, want io.Reader) {
+func DiffReader(tb testing.TB, got, want io.Reader, options ...Option) {
 	tb.Helper()
 
 	gotData, err := io.ReadAll(got)
 	if err != nil {
-		tb.Fatalf("DiffReader: could not read from got: %v\n", err)
+		tb.Fatalf("DiffReader: could not read from got: %v", err)
 	}
 
 	wantData, err := io.ReadAll(want)
 	if err != nil {
-		tb.Fatalf("DiffReader: could not read from want: %v\n", err)
+		tb.Fatalf("DiffReader: could not read from want: %v", err)
 	}
 
-	DiffBytes(tb, gotData, wantData)
+	DiffBytes(tb, gotData, wantData, options...)
 }
 
 // CaptureOutput captures and returns data printed to [os.Stdout] and [os.Stderr] by the provided function fn, allowing
@@ -415,6 +475,9 @@ func DiffReader(tb testing.TB, got, want io.Reader) {
 //
 // If any error occurs capturing stdout or stderr, the test will also be failed with a descriptive log.
 //
+// CaptureOutput replaces the process-wide [os.Stdout] and [os.Stderr] for the duration of the call,
+// so it is NOT safe to use from tests marked with [testing.T.Parallel].
+//
 //	fn := func() error {
 //		fmt.Println("hello stdout")
 //		return nil
@@ -426,84 +489,88 @@ func DiffReader(tb testing.TB, got, want io.Reader) {
 func CaptureOutput(tb testing.TB, fn func() error) (stdout, stderr string) {
 	tb.Helper()
 
-	// Take copies of the original streams
 	oldStdout := os.Stdout
 	oldStderr := os.Stderr
 
-	defer func() {
-		// Restore everything back to normal
-		os.Stdout = oldStdout
-		os.Stderr = oldStderr
-	}()
-
 	stdoutReader, stdoutWriter, err := os.Pipe()
 	if err != nil {
 		tb.Fatalf("CaptureOutput: could not construct an os.Pipe(): %v", err)
+
+		return "", ""
 	}
 
 	stderrReader, stderrWriter, err := os.Pipe()
 	if err != nil {
+		stdoutReader.Close()
+		stdoutWriter.Close()
 		tb.Fatalf("CaptureOutput: could not construct an os.Pipe(): %v", err)
+
+		return "", ""
 	}
 
-	// Set stdout and stderr streams to the pipe writers
 	os.Stdout = stdoutWriter
 	os.Stderr = stderrWriter
 
-	stdoutCapture := make(chan string)
-	stderrCapture := make(chan string)
-
-	var wg sync.WaitGroup
-
-	// Copy in goroutines to avoid blocking
-	wg.Go(func() {
-		defer func() {
-			close(stdoutCapture)
-		}()
-
-		buf := &bytes.Buffer{}
-		if _, err := io.Copy(buf, stdoutReader); err != nil {
-			tb.Fatalf("CaptureOutput: failed to copy from stdout reader: %v", err)
+	// Buffered so the copy goroutines can always deliver their result, even if
+	// the main goroutine exits early via Fatalf / runtime.Goexit / panic.
+	stdoutCapture := make(chan string, 1)
+	stderrCapture := make(chan string, 1)
+
+	// Goroutines use Errorf rather than Fatalf — the testing contract says
+	// FailNow/Fatal* must only be called from the main test goroutine.
+	go copyInto(tb, "stdout", stdoutReader, stdoutCapture)
+	go copyInto(tb, "stderr", stderrReader, stderrCapture)
+
+	// Ensure the real streams are restored and the pipe writers are closed on
+	// every exit path (including panic / Goexit). Closing the writers lets the
+	// copy goroutines see EOF and deliver their buffers to the channels.
+	writersClosed := false
+	closeWriters := func() {
+		if writersClosed {
+			return
 		}
 
-		stdoutCapture <- buf.String()
-	})
+		writersClosed = true
 
-	wg.Go(func() {
-		defer func() {
-			close(stderrCapture)
-		}()
+		stdoutWriter.Close()
+		stderrWriter.Close()
+	}
 
-		buf := &bytes.Buffer{}
-		if _, err := io.Copy(buf, stderrReader); err != nil {
-			tb.Fatalf("CaptureOutput: failed to copy from stderr reader: %v", err)
-		}
+	defer func() {
+		closeWriters()
 
-		stderrCapture <- buf.String()
-	})
+		os.Stdout = oldStdout
+		os.Stderr = oldStderr
+	}()
 
-	// Call the test function that produces the output
-	if err := fn(); err != nil {
-		tb.Fatalf("CaptureOutput: user function returned an error: %v", err)
-	}
+	if fnErr := fn(); fnErr != nil {
+		tb.Fatalf("CaptureOutput: user function returned an error: %v", fnErr)
 
-	// Close the writers
-	stdoutCloseErr := stdoutWriter.Close()
-	if stdoutCloseErr != nil {
-		tb.Fatalf("CaptureOutput: could not close stdout pipe: %v", stdoutCloseErr)
+		return "", ""
 	}
 
-	stderrCloseErr := stderrWriter.Close()
-	if stderrCloseErr != nil {
-		tb.Fatalf("CaptureOutput: could not close stderr pipe: %v", stderrCloseErr)
-	}
+	// Happy path: close writers now so we can receive the captured data before
+	// the defer runs (the defer's close is then a no-op).
+	closeWriters()
+
+	return <-stdoutCapture, <-stderrCapture
+}
+
+// copyInto reads from r into a buffer and sends the result on out. Any copy
+// error is reported against tb via Errorf — Fatal* is unsafe from non-main
+// goroutines. The send uses a buffered channel so it never blocks.
+func copyInto(tb testing.TB, name string, r io.Reader, out chan<- string) {
+	tb.Helper()
 
-	capturedStdout := <-stdoutCapture
-	capturedStderr := <-stderrCapture
+	buf := &bytes.Buffer{}
 
-	wg.Wait()
+	defer func() {
+		out <- buf.String()
+	}()
 
-	return capturedStdout, capturedStderr
+	if _, err := io.Copy(buf, r); err != nil {
+		tb.Errorf("CaptureOutput: failed to copy from %s reader: %v", name, err)
+	}
 }
 
 // If data is empty or ends in \n, fixNL returns data.
diff --git a/test_test.go b/test_test.go
index bd40b83..cbd4cf2 100644
--- a/test_test.go
+++ b/test_test.go
@@ -6,6 +6,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"math"
 	"os"
 	"slices"
 	"testing"
@@ -240,6 +241,34 @@ func TestTest(t *testing.T) {
 			},
 			wantFail: true,
 		},
+		{
+			name: "NotNearlyEqual/pass",
+			fn: func(tb testing.TB) {
+				test.NotNearlyEqual(tb, 3.0000001, 3.0)
+			},
+			wantFail: false,
+		},
+		{
+			name: "NotNearlyEqual/fail",
+			fn: func(tb testing.TB) {
+				test.NotNearlyEqual(tb, 3.0000000001, 3.0)
+			},
+			wantFail: true,
+		},
+		{
+			name: "NotNearlyEqual/fail custom tolerance",
+			fn: func(tb testing.TB) {
+				test.NotNearlyEqual(tb, 3.05, 3.0, test.FloatEqualityThreshold(0.1))
+			},
+			wantFail: true,
+		},
+		{
+			name: "NotNearlyEqual/fail with context",
+			fn: func(tb testing.TB) {
+				test.NotNearlyEqual(tb, 3.0000000001, 3.0, test.Context("Numbers don't work that way"))
+			},
+			wantFail: true,
+		},
 		{
 			name: "Ok/pass",
 			fn: func(tb testing.TB) {
@@ -471,6 +500,59 @@ func TestTest(t *testing.T) {
 			},
 			wantFail: true,
 		},
+		{
+			name: "Diff/fail with title",
+			fn: func(tb testing.TB) {
+				got := "Some\nstuff here in this file\nlines as well wow\nsome more stuff\n"
+				want := "Some\ndifferent stuff here in this file\nthis line is different\nsome more stuff\n"
+				test.Diff(tb, got, want, test.Title("File drift"))
+			},
+			wantFail: true,
+		},
+		{
+			name: "Diff/fail with context",
+			fn: func(tb testing.TB) {
+				got := "Some\nstuff here in this file\nlines as well wow\nsome more stuff\n"
+				want := "Some\ndifferent stuff here in this file\nthis line is different\nsome more stuff\n"
+				test.Diff(tb, got, want, test.Context("config file drifted from checked-in copy"))
+			},
+			wantFail: true,
+		},
+		{
+			name: "Option errors/Title empty",
+			fn: func(tb testing.TB) {
+				test.Equal(tb, 1, 1, test.Title(""))
+			},
+			wantFail: true,
+		},
+		{
+			name: "Option errors/Context empty",
+			fn: func(tb testing.TB) {
+				test.Equal(tb, 1, 1, test.Context(""))
+			},
+			wantFail: true,
+		},
+		{
+			name: "Option errors/Context format resolves empty",
+			fn: func(tb testing.TB) {
+				test.Equal(tb, 1, 1, test.Context("%s", ""))
+			},
+			wantFail: true,
+		},
+		{
+			name: "Option errors/FloatEqualityThreshold positive infinity",
+			fn: func(tb testing.TB) {
+				test.NearlyEqual(tb, 1.0, 1.0, test.FloatEqualityThreshold(math.Inf(1)))
+			},
+			wantFail: true,
+		},
+		{
+			name: "Option errors/FloatEqualityThreshold negative infinity",
+			fn: func(tb testing.TB) {
+				test.NearlyEqual(tb, 1.0, 1.0, test.FloatEqualityThreshold(math.Inf(-1)))
+			},
+			wantFail: true,
+		},
 	}
 
 	for _, tt := range tests {
diff --git a/testdata/snapshots/TestTest/Diff/fail.snap b/testdata/snapshots/TestTest/Diff/fail.snap
index 9158e73..7f78a77 100644
--- a/testdata/snapshots/TestTest/Diff/fail.snap
+++ b/testdata/snapshots/TestTest/Diff/fail.snap
@@ -1,10 +1,11 @@
 source: test_test.go
 expression: buf.String()
 ---
-|+
+|
 
   Diff
   ----
+
   diff want got
   --- want
   +++ got
@@ -15,4 +16,3 @@ expression: buf.String()
   - this line is different
   + lines as well wow
     some more stuff
-
diff --git a/testdata/snapshots/TestTest/Diff/fail_no_trailing_newline.snap b/testdata/snapshots/TestTest/Diff/fail_no_trailing_newline.snap
index 9158e73..7f78a77 100644
--- a/testdata/snapshots/TestTest/Diff/fail_no_trailing_newline.snap
+++ b/testdata/snapshots/TestTest/Diff/fail_no_trailing_newline.snap
@@ -1,10 +1,11 @@
 source: test_test.go
 expression: buf.String()
 ---
-|+
+|
 
   Diff
   ----
+
   diff want got
   --- want
   +++ got
@@ -15,4 +16,3 @@ expression: buf.String()
   - this line is different
   + lines as well wow
     some more stuff
-
diff --git a/testdata/snapshots/TestTest/Diff/fail_with_context.snap b/testdata/snapshots/TestTest/Diff/fail_with_context.snap
new file mode 100644
index 0000000..cfca7f9
--- /dev/null
+++ b/testdata/snapshots/TestTest/Diff/fail_with_context.snap
@@ -0,0 +1,20 @@
+source: test_test.go
+expression: buf.String()
+---
+|
+
+  Diff
+  ----
+
+  diff want got
+  --- want
+  +++ got
+  @@ -1,4 +1,4 @@
+    Some
+  - different stuff here in this file
+  + stuff here in this file
+  - this line is different
+  + lines as well wow
+    some more stuff
+
+  (config file drifted from checked-in copy)
diff --git a/testdata/snapshots/TestTest/Diff/fail_with_title.snap b/testdata/snapshots/TestTest/Diff/fail_with_title.snap
new file mode 100644
index 0000000..2c8ec29
--- /dev/null
+++ b/testdata/snapshots/TestTest/Diff/fail_with_title.snap
@@ -0,0 +1,18 @@
+source: test_test.go
+expression: buf.String()
+---
+|
+
+  File drift
+  ----------
+
+  diff want got
+  --- want
+  +++ got
+  @@ -1,4 +1,4 @@
+    Some
+  - different stuff here in this file
+  + stuff here in this file
+  - this line is different
+  + lines as well wow
+    some more stuff
diff --git a/testdata/snapshots/TestTest/DiffBytes/fail.snap b/testdata/snapshots/TestTest/DiffBytes/fail.snap
index 9158e73..7f78a77 100644
--- a/testdata/snapshots/TestTest/DiffBytes/fail.snap
+++ b/testdata/snapshots/TestTest/DiffBytes/fail.snap
@@ -1,10 +1,11 @@
 source: test_test.go
 expression: buf.String()
 ---
-|+
+|
 
   Diff
   ----
+
   diff want got
   --- want
   +++ got
@@ -15,4 +16,3 @@ expression: buf.String()
   - this line is different
   + lines as well wow
     some more stuff
-
diff --git a/testdata/snapshots/TestTest/DiffReader/fail.snap b/testdata/snapshots/TestTest/DiffReader/fail.snap
index 9158e73..7f78a77 100644
--- a/testdata/snapshots/TestTest/DiffReader/fail.snap
+++ b/testdata/snapshots/TestTest/DiffReader/fail.snap
@@ -1,10 +1,11 @@
 source: test_test.go
 expression: buf.String()
 ---
-|+
+|
 
   Diff
   ----
+
   diff want got
   --- want
   +++ got
@@ -15,4 +16,3 @@ expression: buf.String()
   - this line is different
   + lines as well wow
     some more stuff
-
diff --git a/testdata/snapshots/TestTest/Err/fail.snap b/testdata/snapshots/TestTest/Err/fail.snap
index b409248..38d6194 100644
--- a/testdata/snapshots/TestTest/Err/fail.snap
+++ b/testdata/snapshots/TestTest/Err/fail.snap
@@ -7,4 +7,4 @@ expression: buf.String()
   -------
 
   Got:	<nil>
-  Wanted:	error
+  Wanted:	<any error>
diff --git a/testdata/snapshots/TestTest/Err/fail_with_context.snap b/testdata/snapshots/TestTest/Err/fail_with_context.snap
index df511ae..526d9f3 100644
--- a/testdata/snapshots/TestTest/Err/fail_with_context.snap
+++ b/testdata/snapshots/TestTest/Err/fail_with_context.snap
@@ -7,6 +7,6 @@ expression: buf.String()
   -------
 
   Got:	<nil>
-  Wanted:	error
+  Wanted:	<any error>
 
   (Frobnicated the baz when it should have failed)
diff --git a/testdata/snapshots/TestTest/Err/fail_with_title.snap b/testdata/snapshots/TestTest/Err/fail_with_title.snap
index 8cdb2e2..af5c511 100644
--- a/testdata/snapshots/TestTest/Err/fail_with_title.snap
+++ b/testdata/snapshots/TestTest/Err/fail_with_title.snap
@@ -7,4 +7,4 @@ expression: buf.String()
   -------------------
 
   Got:	<nil>
-  Wanted:	error
+  Wanted:	<any error>
diff --git a/testdata/snapshots/TestTest/NotNearlyEqual/fail.snap b/testdata/snapshots/TestTest/NotNearlyEqual/fail.snap
new file mode 100644
index 0000000..b25cd85
--- /dev/null
+++ b/testdata/snapshots/TestTest/NotNearlyEqual/fail.snap
@@ -0,0 +1,12 @@
+source: test_test.go
+expression: buf.String()
+---
+|
+
+  NearlyEqual
+  -----------
+
+  Got:	3.0000000001
+  Wanted:	3
+
+  Because: Difference 3.0000000001 - 3 = 1.000000082740371e-10 is within tolerance of 1e-08
diff --git a/testdata/snapshots/TestTest/NotNearlyEqual/fail_custom_tolerance.snap b/testdata/snapshots/TestTest/NotNearlyEqual/fail_custom_tolerance.snap
new file mode 100644
index 0000000..67354d0
--- /dev/null
+++ b/testdata/snapshots/TestTest/NotNearlyEqual/fail_custom_tolerance.snap
@@ -0,0 +1,12 @@
+source: test_test.go
+expression: buf.String()
+---
+|
+
+  NearlyEqual
+  -----------
+
+  Got:	3.05
+  Wanted:	3
+
+  Because: Difference 3.05 - 3 = 0.04999999999999982 is within tolerance of 0.1
diff --git a/testdata/snapshots/TestTest/NotNearlyEqual/fail_with_context.snap b/testdata/snapshots/TestTest/NotNearlyEqual/fail_with_context.snap
new file mode 100644
index 0000000..6d62fb2
--- /dev/null
+++ b/testdata/snapshots/TestTest/NotNearlyEqual/fail_with_context.snap
@@ -0,0 +1,14 @@
+source: test_test.go
+expression: buf.String()
+---
+|
+
+  NearlyEqual
+  -----------
+
+  Got:	3.0000000001
+  Wanted:	3
+
+  (Numbers don't work that way)
+
+  Because: Difference 3.0000000001 - 3 = 1.000000082740371e-10 is within tolerance of 1e-08
diff --git a/testdata/snapshots/TestTest/Option_errors/Context_empty.snap b/testdata/snapshots/TestTest/Option_errors/Context_empty.snap
new file mode 100644
index 0000000..0c7b0c4
--- /dev/null
+++ b/testdata/snapshots/TestTest/Option_errors/Context_empty.snap
@@ -0,0 +1,4 @@
+source: test_test.go
+expression: buf.String()
+---
+'Equal: could not apply options: cannot set context to an empty string'
diff --git a/testdata/snapshots/TestTest/Option_errors/Context_format_resolves_empty.snap b/testdata/snapshots/TestTest/Option_errors/Context_format_resolves_empty.snap
new file mode 100644
index 0000000..0c7b0c4
--- /dev/null
+++ b/testdata/snapshots/TestTest/Option_errors/Context_format_resolves_empty.snap
@@ -0,0 +1,4 @@
+source: test_test.go
+expression: buf.String()
+---
+'Equal: could not apply options: cannot set context to an empty string'
diff --git a/testdata/snapshots/TestTest/Option_errors/FloatEqualityThreshold_negative_infinity.snap b/testdata/snapshots/TestTest/Option_errors/FloatEqualityThreshold_negative_infinity.snap
new file mode 100644
index 0000000..1cab5cd
--- /dev/null
+++ b/testdata/snapshots/TestTest/Option_errors/FloatEqualityThreshold_negative_infinity.snap
@@ -0,0 +1,4 @@
+source: test_test.go
+expression: buf.String()
+---
+'NearlyEqual: could not apply options: cannot set floating point equality threshold to ±infinity'
diff --git a/testdata/snapshots/TestTest/Option_errors/FloatEqualityThreshold_positive_infinity.snap b/testdata/snapshots/TestTest/Option_errors/FloatEqualityThreshold_positive_infinity.snap
new file mode 100644
index 0000000..1cab5cd
--- /dev/null
+++ b/testdata/snapshots/TestTest/Option_errors/FloatEqualityThreshold_positive_infinity.snap
@@ -0,0 +1,4 @@
+source: test_test.go
+expression: buf.String()
+---
+'NearlyEqual: could not apply options: cannot set floating point equality threshold to ±infinity'
diff --git a/testdata/snapshots/TestTest/Option_errors/Title_empty.snap b/testdata/snapshots/TestTest/Option_errors/Title_empty.snap
new file mode 100644
index 0000000..7305a09
--- /dev/null
+++ b/testdata/snapshots/TestTest/Option_errors/Title_empty.snap
@@ -0,0 +1,4 @@
+source: test_test.go
+expression: buf.String()
+---
+'Equal: could not apply options: cannot set title to an empty string'
diff --git a/testdata/snapshots/TestTest/WantErr/fail_nil.snap b/testdata/snapshots/TestTest/WantErr/fail_nil.snap
index 594ae96..5cd6321 100644
--- a/testdata/snapshots/TestTest/WantErr/fail_nil.snap
+++ b/testdata/snapshots/TestTest/WantErr/fail_nil.snap
@@ -7,6 +7,6 @@ expression: buf.String()
   -------
 
   Got:	<nil>
-  Wanted:	error
+  Wanted:	<any error>
 
   Because: Wanted an error but got <nil>