From 0ea9e415c351ca7289a4aacfd4ec79585e452d29 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Wed, 17 Jan 2024 22:20:26 -0800
Subject: [PATCH 01/11] First cut at a test.

---
 .../kotlin/undertest/junit5/UT_BinaryTest.kt  | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 undertest-junit5/src/test/kotlin/undertest/junit5/UT_BinaryTest.kt

diff --git a/undertest-junit5/src/test/kotlin/undertest/junit5/UT_BinaryTest.kt b/undertest-junit5/src/test/kotlin/undertest/junit5/UT_BinaryTest.kt
new file mode 100644
index 00000000..d93c7045
--- /dev/null
+++ b/undertest-junit5/src/test/kotlin/undertest/junit5/UT_BinaryTest.kt
@@ -0,0 +1,22 @@
+package undertest.junit5
+
+import com.diffplug.selfie.Selfie.expectSelfie
+import kotlin.test.Test
+
+class UT_BinaryTest {
+  @Test fun emptyOnDisk() {
+    expectSelfie(byteArrayOf()).toMatchDisk_TODO()
+  }
+
+  @Test fun emptyInline() {
+    expectSelfie(byteArrayOf()).toBe_TODO()
+  }
+
+  @Test fun bigishOnDisk() {
+    expectSelfie(ByteArray(256) { it.toByte() }).toMatchDisk_TODO()
+  }
+
+  @Test fun bigishInline() {
+    expectSelfie(ByteArray(256) { it.toByte() }).toBe_TODO()
+  }
+}

From 2367fc93e2f4c6f66f389d29bb2260a50aa5b3b0 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Wed, 17 Jan 2024 23:08:05 -0800
Subject: [PATCH 02/11] Replace our made-up `StringWriter` with `Appendable`
 which is part of KMP it turns out!

---
 .../kotlin/com/diffplug/selfie/Selfie.kt      |  7 ++-
 .../com/diffplug/selfie/SnapshotFile.kt       | 46 ++++++++++++-------
 .../com/diffplug/selfie/SnapshotFileTest.kt   |  6 +--
 .../junit5/SelfieTestExecutionListener.kt     |  2 +-
 4 files changed, 37 insertions(+), 24 deletions(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
index 94807560..170612cf 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
@@ -203,8 +203,7 @@ object Selfie {
    * missing facets.
    */
   private fun serializeOnlyFacets(snapshot: Snapshot, keys: Collection<String>): String {
-    val buf = StringBuilder()
-    val writer = StringWriter { buf.append(it) }
+    val writer = StringBuilder()
     for (key in keys) {
       if (key.isEmpty()) {
         SnapshotFile.writeValue(writer, snapshot.subjectOrFacet(key))
@@ -215,8 +214,8 @@ object Selfie {
         }
       }
     }
-    buf.setLength(buf.length - 1)
-    return buf.toString()
+    writer.setLength(writer.length - 1)
+    return writer.toString()
   }
 }
 
diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
index c519708b..53318fbf 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
@@ -136,10 +136,8 @@ class SnapshotFile {
   // this will probably become `<String, JsonObject>` we'll cross that bridge when we get to it
   var metadata: Map.Entry<String, String>? = null
   var snapshots = ArrayMap.empty<String, Snapshot>()
-  fun serialize(valueWriterRaw: StringWriter) {
-    val valueWriter =
-        if (unixNewlines) valueWriterRaw
-        else StringWriter { valueWriterRaw.write(it.efficientReplace("\n", "\r\n")) }
+  fun serialize(valueWriterRaw: Appendable) {
+    val valueWriter = if (unixNewlines) valueWriterRaw else ConvertToWindowsNewlines(valueWriterRaw)
     metadata?.let {
       writeKey(valueWriter, "📷 ${it.key}", null)
       writeValue(valueWriter, SnapshotValue.of(it.value))
@@ -198,17 +196,17 @@ class SnapshotFile {
       result.unixNewlines = unixNewlines
       return result
     }
-    internal fun writeKey(valueWriter: StringWriter, key: String, facet: String?) {
-      valueWriter.write("╔═ ")
-      valueWriter.write(SnapshotValueReader.nameEsc.escape(key))
+    internal fun writeKey(valueWriter: Appendable, key: String, facet: String?) {
+      valueWriter.append("╔═ ")
+      valueWriter.append(SnapshotValueReader.nameEsc.escape(key))
       if (facet != null) {
-        valueWriter.write("[")
-        valueWriter.write(SnapshotValueReader.nameEsc.escape(facet))
-        valueWriter.write("]")
+        valueWriter.append("[")
+        valueWriter.append(SnapshotValueReader.nameEsc.escape(facet))
+        valueWriter.append("]")
       }
-      valueWriter.write(" ═╗\n")
+      valueWriter.append(" ═╗\n")
     }
-    internal fun writeValue(valueWriter: StringWriter, value: SnapshotValue) {
+    internal fun writeValue(valueWriter: Appendable, value: SnapshotValue) {
       if (value.isBinary) {
         TODO("BASE64")
       } else {
@@ -216,8 +214,8 @@ class SnapshotFile {
             SnapshotValueReader.bodyEsc
                 .escape(value.valueString())
                 .efficientReplace("\n╔", "\n\uD801\uDF41")
-        valueWriter.write(escaped)
-        valueWriter.write("\n")
+        valueWriter.append(escaped)
+        valueWriter.append("\n")
       }
     }
   }
@@ -377,6 +375,22 @@ expect class LineReader {
     fun forBinary(content: ByteArray): LineReader
   }
 }
-fun interface StringWriter {
-  fun write(string: String)
+
+internal class ConvertToWindowsNewlines(val sink: Appendable) : Appendable {
+  override fun append(value: Char): Appendable {
+    if (value != '\n') sink.append(value)
+    else {
+      sink.append('\r')
+      sink.append('\n')
+    }
+    return this
+  }
+  override fun append(value: CharSequence?): Appendable {
+    value?.let { sink.append(it.toString().efficientReplace("\n", "\r\n")) }
+    return this
+  }
+  override fun append(value: CharSequence?, startIndex: Int, endIndex: Int): Appendable {
+    value?.let { sink.append(it.substring(startIndex, endIndex).efficientReplace("\n", "\r\n")) }
+    return this
+  }
 }
diff --git a/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotFileTest.kt b/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotFileTest.kt
index 721766be..0a0a82c7 100644
--- a/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotFileTest.kt
+++ b/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotFileTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 DiffPlug
+ * Copyright (C) 2023-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,8 +72,8 @@ class SnapshotFileTest {
             "Apple",
             Snapshot.of("Granny Smith").plusFacet("color", "green").plusFacet("crisp", "yes"))
     underTest.snapshots = underTest.snapshots.plus("Orange", Snapshot.of("Orange"))
-    val buffer = StringBuffer()
-    underTest.serialize { line -> buffer.append(line) }
+    val buffer = StringBuilder()
+    underTest.serialize(buffer)
     buffer.toString() shouldBe
         """
             ╔═ 📷 com.acme.AcmeTest ═╗
diff --git a/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/junit5/SelfieTestExecutionListener.kt b/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/junit5/SelfieTestExecutionListener.kt
index 0b1a6bf8..6c6e6722 100644
--- a/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/junit5/SelfieTestExecutionListener.kt
+++ b/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/junit5/SelfieTestExecutionListener.kt
@@ -177,7 +177,7 @@ internal class ClassProgress(val parent: Progress, val className: String) {
           parent.markPathAsWritten(parent.layout.snapshotPathForClass(className))
           Files.createDirectories(snapshotPath.toPath().parent)
           Files.newBufferedWriter(snapshotPath.toPath(), StandardCharsets.UTF_8).use { writer ->
-            file!!.serialize(writer::write)
+            file!!.serialize(writer)
           }
         }
       }

From 7e584447b80a3658e9446d9ab671293f936432aa Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Wed, 17 Jan 2024 23:15:54 -0800
Subject: [PATCH 03/11] Write binary to disk.

---
 .../commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
index 53318fbf..0f339cff 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
@@ -15,6 +15,8 @@
  */
 package com.diffplug.selfie
 
+import kotlin.io.encoding.Base64
+import kotlin.io.encoding.ExperimentalEncodingApi
 import kotlin.jvm.JvmStatic
 
 class ParseException private constructor(val line: Int, message: String?, cause: Throwable?) :
@@ -206,17 +208,19 @@ class SnapshotFile {
       }
       valueWriter.append(" ═╗\n")
     }
+
+    @OptIn(ExperimentalEncodingApi::class)
     internal fun writeValue(valueWriter: Appendable, value: SnapshotValue) {
       if (value.isBinary) {
-        TODO("BASE64")
+        Base64.Mime.encodeToAppendable(value.valueBinary(), valueWriter)
       } else {
         val escaped =
             SnapshotValueReader.bodyEsc
                 .escape(value.valueString())
                 .efficientReplace("\n╔", "\n\uD801\uDF41")
         valueWriter.append(escaped)
-        valueWriter.append("\n")
       }
+      valueWriter.append("\n")
     }
   }
 }

From e27a6e6ace7cfa96a76749ae0819c57efd691e90 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Wed, 17 Jan 2024 23:16:10 -0800
Subject: [PATCH 04/11] Write binary to inline snapshot.

---
 .../src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt     | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
index 170612cf..51fe94a2 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
@@ -25,6 +25,8 @@ import com.diffplug.selfie.guts.LiteralValue
 import com.diffplug.selfie.guts.SnapshotStorage
 import com.diffplug.selfie.guts.initStorage
 import com.diffplug.selfie.guts.recordCall
+import kotlin.io.encoding.Base64
+import kotlin.io.encoding.ExperimentalEncodingApi
 import kotlin.jvm.JvmOverloads
 import kotlin.jvm.JvmStatic
 
@@ -93,12 +95,14 @@ object Selfie {
     fun facet(facet: String) = LiteralStringSelfie(actual, listOf(facet))
     /** Extract a multiple facets from a snapshot in order to do an inline snapshot. */
     fun facets(vararg facets: String) = LiteralStringSelfie(actual, facets.toList())
+
+    @OptIn(ExperimentalEncodingApi::class)
     private fun actualString(): String {
       if (actual.facets.isEmpty() || onlyFacets?.size == 1) {
         // single value doesn't have to worry about escaping at all
         val onlyValue = actual.subjectOrFacet(onlyFacets?.first() ?: "")
         return if (onlyValue.isBinary) {
-          TODO("BASE64")
+          Base64.Mime.encode(onlyValue.valueBinary())
         } else onlyValue.valueString()
       } else {
         return serializeOnlyFacets(

From 5b449488998d9efcff80960060faf1f9151252a4 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Wed, 17 Jan 2024 23:22:56 -0800
Subject: [PATCH 05/11] Fix carriage returns in inline snapshots.

---
 selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
index 51fe94a2..05eb7748 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
@@ -102,7 +102,7 @@ object Selfie {
         // single value doesn't have to worry about escaping at all
         val onlyValue = actual.subjectOrFacet(onlyFacets?.first() ?: "")
         return if (onlyValue.isBinary) {
-          Base64.Mime.encode(onlyValue.valueBinary())
+          Base64.Mime.encode(onlyValue.valueBinary()).replace("\r", ""  )
         } else onlyValue.valueString()
       } else {
         return serializeOnlyFacets(

From 518b589dadcccd50c3c364bdf4233e553067bea0 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Wed, 17 Jan 2024 23:23:02 -0800
Subject: [PATCH 06/11] Fix carriage returns on disk.

---
 selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt | 2 +-
 .../src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt  | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
index 05eb7748..e94749ab 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
@@ -102,7 +102,7 @@ object Selfie {
         // single value doesn't have to worry about escaping at all
         val onlyValue = actual.subjectOrFacet(onlyFacets?.first() ?: "")
         return if (onlyValue.isBinary) {
-          Base64.Mime.encode(onlyValue.valueBinary()).replace("\r", ""  )
+          Base64.Mime.encode(onlyValue.valueBinary()).replace("\r", "")
         } else onlyValue.valueString()
       } else {
         return serializeOnlyFacets(
diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
index 0f339cff..81442a4c 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
@@ -212,7 +212,8 @@ class SnapshotFile {
     @OptIn(ExperimentalEncodingApi::class)
     internal fun writeValue(valueWriter: Appendable, value: SnapshotValue) {
       if (value.isBinary) {
-        Base64.Mime.encodeToAppendable(value.valueBinary(), valueWriter)
+        val escaped = Base64.Mime.encode(value.valueBinary())
+        valueWriter.append(escaped.efficientReplace("\r", ""))
       } else {
         val escaped =
             SnapshotValueReader.bodyEsc

From 102c266f6b92668019853c4b7f8070a66828f0fb Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Thu, 18 Jan 2024 00:19:08 -0800
Subject: [PATCH 07/11] Add support for parsing binary values in snapshots.

---
 .../com/diffplug/selfie/SnapshotFile.kt       | 11 ++++++--
 .../com/diffplug/selfie/SnapshotReaderTest.kt | 28 ++++++++++++++++++-
 .../selfie/SnapshotValueReaderTest.kt         | 11 +++++++-
 3 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
index 81442a4c..d4eed8bf 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
@@ -253,7 +253,7 @@ class SnapshotReader(val valueReader: SnapshotValueReader) {
       val facetEndIdx = nextKey.indexOf(']', facetIdx + 1)
       require(facetEndIdx != -1) { "Missing ] in $nextKey" }
       val facetName = nextKey.substring(facetIdx + 1, facetEndIdx)
-      snapshot = snapshot.plusFacet(facetName, valueReader.nextValue().valueString())
+      snapshot = snapshot.plusFacet(facetName, valueReader.nextValue())
     }
   }
   fun skipSnapshot() {
@@ -276,9 +276,11 @@ class SnapshotValueReader(val lineReader: LineReader) {
   }
 
   /** Reads the next value. */
+  @OptIn(ExperimentalEncodingApi::class)
   fun nextValue(): SnapshotValue {
     // validate key
     nextKey()
+    val isBase64 = nextLine()!!.contains(FLAG_BASE64)
     resetLine()
 
     // read value
@@ -292,12 +294,14 @@ class SnapshotValueReader(val lineReader: LineReader) {
       }
       buffer.append('\n')
     }
-    return SnapshotValue.of(
+    val stringValue =
         if (buffer.isEmpty()) ""
         else {
           buffer.setLength(buffer.length - 1)
           bodyEsc.unescape(buffer.toString())
-        })
+        }
+    return if (isBase64) SnapshotValue.of(Base64.Mime.decode(stringValue))
+    else SnapshotValue.of(stringValue)
   }
 
   /** Same as nextValue, but faster. */
@@ -359,6 +363,7 @@ class SnapshotValueReader(val lineReader: LineReader) {
     private const val KEY_FIRST_CHAR = '╔'
     private const val KEY_START = "╔═ "
     private const val KEY_END = " ═╗"
+    private const val FLAG_BASE64 = " ═╗ base64"
 
     /**
      * https://github.com/diffplug/selfie/blob/main/selfie-lib/src/commonTest/resources/com/diffplug/selfie/scenarios_and_lenses.ss
diff --git a/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotReaderTest.kt b/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotReaderTest.kt
index e9f52a33..d10921ba 100644
--- a/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotReaderTest.kt
+++ b/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotReaderTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 DiffPlug
+ * Copyright (C) 2023-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,4 +44,30 @@ class SnapshotReaderTest {
     reader.nextSnapshot() shouldBe Snapshot.of("Orange")
     reader.peekKey() shouldBe null
   }
+
+  @Test
+  fun binary() {
+    val reader =
+        SnapshotReader(
+            SnapshotValueReader.of(
+                """
+            ╔═ Apple ═╗
+            Apple
+            ╔═ Apple[color] ═╗ base64 length 3 bytes
+            c2Fk
+            ╔═ Apple[crisp] ═╗
+            yes
+            ╔═ Orange ═╗ base64 length 3 bytes
+            c2Fk
+        """
+                    .trimIndent()))
+    reader.peekKey() shouldBe "Apple"
+    reader.peekKey() shouldBe "Apple"
+    reader.nextSnapshot() shouldBe
+        Snapshot.of("Apple").plusFacet("color", "sad".toByteArray()).plusFacet("crisp", "yes")
+    reader.peekKey() shouldBe "Orange"
+    reader.peekKey() shouldBe "Orange"
+    reader.nextSnapshot() shouldBe Snapshot.of("sad".toByteArray())
+    reader.peekKey() shouldBe null
+  }
 }
diff --git a/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotValueReaderTest.kt b/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotValueReaderTest.kt
index dcd10298..785accd8 100644
--- a/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotValueReaderTest.kt
+++ b/selfie-lib/src/jvmTest/kotlin/com/diffplug/selfie/SnapshotValueReaderTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 DiffPlug
+ * Copyright (C) 2023-2024 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -163,4 +163,13 @@ class SnapshotValueReaderTest {
       reader.skipValue()
     }
   }
+
+  @Test
+  fun binary() {
+    val reader = SnapshotValueReader.of("""╔═ Apple ═╗ base64 length 3 bytes
+c2Fk
+""")
+    reader.peekKey() shouldBe "Apple"
+    reader.nextValue().valueBinary() shouldBe "sad".toByteArray()
+  }
 }

From 04e59ce9bc58ab34fc579ac6caab33dea03c2186 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Thu, 18 Jan 2024 00:49:18 -0800
Subject: [PATCH 08/11] Write binary snapshots.

---
 .../kotlin/com/diffplug/selfie/Selfie.kt      | 17 +++++----
 .../com/diffplug/selfie/SnapshotFile.kt       | 37 ++++++++++++-------
 2 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
index e94749ab..2b904037 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Selfie.kt
@@ -210,16 +210,19 @@ object Selfie {
     val writer = StringBuilder()
     for (key in keys) {
       if (key.isEmpty()) {
-        SnapshotFile.writeValue(writer, snapshot.subjectOrFacet(key))
+        SnapshotFile.writeEntry(writer, "", null, snapshot.subjectOrFacet(key))
       } else {
-        snapshot.subjectOrFacetMaybe(key)?.let {
-          SnapshotFile.writeKey(writer, "", key)
-          SnapshotFile.writeValue(writer, it)
-        }
+        snapshot.subjectOrFacetMaybe(key)?.let { SnapshotFile.writeEntry(writer, "", key, it) }
       }
     }
-    writer.setLength(writer.length - 1)
-    return writer.toString()
+    val EMPTY_KEY_AND_FACET = "╔═  ═╗\n"
+    return if (writer.startsWith(EMPTY_KEY_AND_FACET)) {
+      // this codepath is triggered by the `key.isEmpty()` line above
+      writer.subSequence(EMPTY_KEY_AND_FACET.length, writer.length - 1).toString()
+    } else {
+      writer.setLength(writer.length - 1)
+      writer.toString()
+    }
   }
 }
 
diff --git a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
index d4eed8bf..5f1f53f3 100644
--- a/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
+++ b/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/SnapshotFile.kt
@@ -140,19 +140,14 @@ class SnapshotFile {
   var snapshots = ArrayMap.empty<String, Snapshot>()
   fun serialize(valueWriterRaw: Appendable) {
     val valueWriter = if (unixNewlines) valueWriterRaw else ConvertToWindowsNewlines(valueWriterRaw)
-    metadata?.let {
-      writeKey(valueWriter, "📷 ${it.key}", null)
-      writeValue(valueWriter, SnapshotValue.of(it.value))
-    }
+    metadata?.let { writeEntry(valueWriter, "📷 ${it.key}", null, SnapshotValue.of(it.value)) }
     snapshots.entries.forEach { entry ->
-      writeKey(valueWriter, entry.key, null)
-      writeValue(valueWriter, entry.value.subject)
+      writeEntry(valueWriter, entry.key, null, entry.value.subject)
       for (facet in entry.value.facets.entries) {
-        writeKey(valueWriter, entry.key, facet.key)
-        writeValue(valueWriter, facet.value)
+        writeEntry(valueWriter, entry.key, facet.key, facet.value)
       }
     }
-    writeKey(valueWriter, "", "end of file")
+    writeEntry(valueWriter, "", "end of file", SnapshotValue.of(""))
   }
 
   var wasSetAtTestTime: Boolean = false
@@ -198,7 +193,14 @@ class SnapshotFile {
       result.unixNewlines = unixNewlines
       return result
     }
-    internal fun writeKey(valueWriter: Appendable, key: String, facet: String?) {
+
+    @OptIn(ExperimentalEncodingApi::class)
+    internal fun writeEntry(
+        valueWriter: Appendable,
+        key: String,
+        facet: String?,
+        value: SnapshotValue
+    ) {
       valueWriter.append("╔═ ")
       valueWriter.append(SnapshotValueReader.nameEsc.escape(key))
       if (facet != null) {
@@ -206,11 +208,18 @@ class SnapshotFile {
         valueWriter.append(SnapshotValueReader.nameEsc.escape(facet))
         valueWriter.append("]")
       }
-      valueWriter.append(" ═╗\n")
-    }
+      valueWriter.append(" ═╗")
+      if (value.isBinary) {
+        valueWriter.append(" base64 length ")
+        valueWriter.append(value.valueBinary().size.toString())
+        valueWriter.append(" bytes")
+      }
+      valueWriter.append("\n")
+
+      if (key.isEmpty() && facet == "end of file") {
+        return
+      }
 
-    @OptIn(ExperimentalEncodingApi::class)
-    internal fun writeValue(valueWriter: Appendable, value: SnapshotValue) {
       if (value.isBinary) {
         val escaped = Base64.Mime.encode(value.valueBinary())
         valueWriter.append(escaped.efficientReplace("\r", ""))

From 523ff8006386b39301ef3e7b4065f759110ac1aa Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Thu, 18 Jan 2024 00:52:45 -0800
Subject: [PATCH 09/11] Add an end-to-end test of the base64.

---
 .../com/diffplug/selfie/junit5/BinaryTest.kt  | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 selfie-runner-junit5/src/test/kotlin/com/diffplug/selfie/junit5/BinaryTest.kt

diff --git a/selfie-runner-junit5/src/test/kotlin/com/diffplug/selfie/junit5/BinaryTest.kt b/selfie-runner-junit5/src/test/kotlin/com/diffplug/selfie/junit5/BinaryTest.kt
new file mode 100644
index 00000000..82eb0eab
--- /dev/null
+++ b/selfie-runner-junit5/src/test/kotlin/com/diffplug/selfie/junit5/BinaryTest.kt
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2024 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.selfie.junit5
+
+import kotlin.test.Test
+import org.junit.jupiter.api.MethodOrderer
+import org.junit.jupiter.api.Order
+import org.junit.jupiter.api.TestMethodOrder
+import org.junitpioneer.jupiter.DisableIfTestFails
+
+@TestMethodOrder(MethodOrderer.OrderAnnotation::class)
+@DisableIfTestFails
+class BinaryTest : Harness("undertest-junit5") {
+  @Test @Order(1)
+  fun readFailsBecauseTodo() {
+    gradleReadSSFail()
+  }
+
+  @Test @Order(2)
+  fun writeSucceeds() {
+    gradleWriteSS()
+  }
+
+  @Test @Order(3)
+  fun nowReadSucceeds() {
+    gradleReadSS()
+  }
+
+  @Test @Order(4)
+  fun cleanup() {
+    ut_mirror().restoreFromGit()
+    ut_snapshot().deleteIfExists()
+  }
+}

From cdaa255268ea5304298bc422c3e51e0fdcffcc4d Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Thu, 18 Jan 2024 00:57:51 -0800
Subject: [PATCH 10/11] Update changelog and readme now that we're
 1.0-complete.

---
 CHANGELOG.md | 4 ++++
 README.md    | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 77d6fd3d..e4a3abe9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Full support for binary snapshots. ([#108](https://github.com/diffplug/selfie/pull/108))
+### Fixed
+- Groovy multiline string values just go into `"` strings instead of `"""` until we have a chance to implement them properly. ([#107](https://github.com/diffplug/selfie/pull/107))
 
 ## [0.3.0] - 2024-01-17
 ### Added
diff --git a/README.md b/README.md
index 0822ab48..153a2616 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@ Snapshot testing is the [fastest and most precise mechanism to record and specif
 
 Robots are writing their own code. Are you still writing assertions by hand?
 
-- *Almost* production ready for [JVM](https://selfie.diffplug.com/jvm).
+- Production ready for [JVM](https://selfie.diffplug.com/jvm).
   - see [the changelog](CHANGELOG.md) to see the remaining "known broken" items.
 - Help wanted using Kotlin Multiplatform for js and wasm (node and browser) ([#84](https://github.com/diffplug/selfie/issues/84)).
 - Help also wanted for non-Kotlin platforms such as python and go ([#85](https://github.com/diffplug/selfie/issues/85)).

From b8ada400ac3835e09e36835612b9f4d055f4e560 Mon Sep 17 00:00:00 2001
From: Ned Twigg <ned.twigg@diffplug.com>
Date: Thu, 18 Jan 2024 01:02:28 -0800
Subject: [PATCH 11/11] Missed on save.

---
 README.md | 1 -
 1 file changed, 1 deletion(-)

diff --git a/README.md b/README.md
index 153a2616..b9a21688 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,6 @@ Snapshot testing is the [fastest and most precise mechanism to record and specif
 Robots are writing their own code. Are you still writing assertions by hand?
 
 - Production ready for [JVM](https://selfie.diffplug.com/jvm).
-  - see [the changelog](CHANGELOG.md) to see the remaining "known broken" items.
 - Help wanted using Kotlin Multiplatform for js and wasm (node and browser) ([#84](https://github.com/diffplug/selfie/issues/84)).
 - Help also wanted for non-Kotlin platforms such as python and go ([#85](https://github.com/diffplug/selfie/issues/85)).