fix: Calculate length of posts and polls with emojis correctly (#315)

Mastodon counts post lengths by considering emojis to be single
characters, no matter how many unicode code points they are composed of.
So "😜" has length 1.

Pachli was using `String.length`, which considers "😜" as length 2.

Correct the calculation by using a BreakIterator to count the characters
in the string, which treats multi-character emojis as a length 1.

Poll options had a similar problem, exacerbated by the Mastodon web UI
also having the same problem, see
https://github.com/mastodon/mastodon/issues/28336.

Fix that by creating `MastodonLengthFilter`, an `InputFilter` that does
the right thing for regular text that may contain emojis.

See also https://github.com/tuskyapp/Tusky/pull/4152, which has the fix
for status length but not polls.

---------

Co-authored-by: Konrad Pozniak <opensource@connyduck.at>

app/lint-baseline.xml

@@ -872,7 +872,7 @@
         errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/components/account/AccountActivity.kt"
-            line="484"
+            line="492"
             column="9"/>
     </issue>
 
@@ -2082,7 +2082,7 @@
         errorLine2="                            ~~~~~~~">
         <location
             file="src/main/java/app/pachli/components/account/AccountActivity.kt"
-            line="372"
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@@ -2093,7 +2093,7 @@
         errorLine2="                            ~~~~~~~">
         <location
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     </issue>
 
@@ -2104,7 +2104,7 @@
         errorLine2="                    ~~~~~~~">
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             file="src/main/java/app/pachli/components/account/AccountActivity.kt"
-            line="381"
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@@ -2115,7 +2115,7 @@
         errorLine2="                    ~~~~~~~">
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+            line="390"
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@@ -2126,7 +2126,7 @@
         errorLine2="                    ~~~~~~~">
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-            line="384"
+            line="392"
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     </issue>
 
@@ -2137,7 +2137,7 @@
         errorLine2="                    ~~~~~~~">
         <location
             file="src/main/java/app/pachli/components/account/AccountActivity.kt"
-            line="394"
+            line="402"
             column="21"/>
     </issue>
 
@@ -2159,7 +2159,7 @@
         errorLine2="                            ~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/components/preference/AccountPreferencesFragment.kt"
-            line="318"
+            line="309"
             column="29"/>
     </issue>
 
@@ -2170,7 +2170,7 @@
         errorLine2="                        ~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/components/preference/AccountPreferencesFragment.kt"
-            line="324"
+            line="315"
             column="25"/>
     </issue>
 
@@ -2324,7 +2324,7 @@
         errorLine2="            ~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/BaseActivity.kt"
-            line="105"
+            line="103"
             column="13"/>
     </issue>
 
@@ -3138,7 +3138,7 @@
         errorLine2="                ~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/MainActivity.kt"
-            line="725"
+            line="722"
             column="17"/>
     </issue>
 
@@ -3149,7 +3149,7 @@
         errorLine2="                    ~~~~~~~">
         <location
             file="src/main/java/app/pachli/MainActivity.kt"
-            line="728"
+            line="725"
             column="21"/>
     </issue>
 
@@ -3158,20 +3158,20 @@
         message="Access to `private` method `secondaryDrawerItem` of class `MainActivityKt` requires synthetic accessor"
         errorLine1="                secondaryDrawerItem {"
         errorLine2="                ~~~~~~~~~~~~~~~~~~~">
+        <location
+            file="src/main/java/app/pachli/MainActivity.kt"
+            line="730"
+            column="17"/>
+    </issue>
+
+    <issue
+        id="SyntheticAccessor"
+        message="Access to `private` method `setOnClick` of class `MainActivityKt` requires synthetic accessor"
+        errorLine1="                    onClick = {"
+        errorLine2="                    ~~~~~~~">
         <location
             file="src/main/java/app/pachli/MainActivity.kt"
             line="733"
-            column="17"/>
-    </issue>
-
-    <issue
-        id="SyntheticAccessor"
-        message="Access to `private` method `setOnClick` of class `MainActivityKt` requires synthetic accessor"
-        errorLine1="                    onClick = {"
-        errorLine2="                    ~~~~~~~">
-        <location
-            file="src/main/java/app/pachli/MainActivity.kt"
-            line="736"
             column="21"/>
     </issue>
 
@@ -3182,7 +3182,7 @@
         errorLine2="                ~~~~~~~~~~~~~~~~~~~">
         <location
             file="src/main/java/app/pachli/MainActivity.kt"
-            line="741"
+            line="738"
             column="17"/>
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@@ -3193,7 +3193,7 @@
         errorLine2="                    ~~~~~~~">
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     </issue>
 
@@ -3204,7 +3204,7 @@
         errorLine2="                    ~~~~~~~~~~~~~~~~~">
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             file="src/main/java/app/pachli/MainActivity.kt"
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+            line="748"
             column="21"/>
     </issue>
 
@@ -3215,7 +3215,7 @@
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@@ -3226,7 +3226,7 @@
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@@ -3237,7 +3237,7 @@
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@@ -3248,7 +3248,7 @@
         errorLine2="                ~~~~~~~~~~~~~~~~~~~">
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             file="src/main/java/app/pachli/MainActivity.kt"
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     </issue>
 
@@ -3259,7 +3259,7 @@
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         <location
             file="src/main/java/app/pachli/MainActivity.kt"
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@@ -3270,7 +3270,7 @@
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             file="src/main/java/app/pachli/MainActivity.kt"
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+            line="905"
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     </issue>
 
@@ -3281,7 +3281,7 @@
         errorLine2="                ~~~~~~~~~~~~~~~~~~~~~~~~~">
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             file="src/main/java/app/pachli/MainActivity.kt"
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+            line="907"
             column="17"/>
     </issue>
 
@@ -3292,7 +3292,7 @@
         errorLine2="                ~~~~~~~~~~~~~~~~~~~~~~~~~">
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             file="src/main/java/app/pachli/MainActivity.kt"
-            line="921"
+            line="918"
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     </issue>
 
@@ -3904,7 +3904,7 @@
         errorLine2="                     ~~~~~~~~">
         <location
             file="src/main/res/layout/activity_account.xml"
-            line="242"
+            line="243"
             column="22"/>
     </issue>
 
@@ -3915,7 +3915,7 @@
         errorLine2="                         ~~~~~~~~">
         <location
             file="src/main/res/layout/activity_account.xml"
-            line="278"
+            line="279"
             column="26"/>
     </issue>
 
@@ -3926,7 +3926,7 @@
         errorLine2="                         ~~~~~~~~">
         <location
             file="src/main/res/layout/activity_account.xml"
-            line="305"
+            line="306"
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     </issue>
 
@@ -3937,7 +3937,7 @@
         errorLine2="                         ~~~~~~~~">
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             file="src/main/res/layout/activity_account.xml"
-            line="320"
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     </issue>
 
@@ -3948,7 +3948,7 @@
         errorLine2="                         ~~~~~~~~">
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-            line="347"
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@@ -3959,7 +3959,7 @@
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-            line="378"
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     </issue>
 
@@ -3970,7 +3970,7 @@
         errorLine2="                         ~~~~~~~~">
         <location
             file="src/main/res/layout/activity_account.xml"
-            line="408"
+            line="409"
             column="26"/>
     </issue>
 

app/src/main/java/app/pachli/components/compose/ComposeActivity.kt

@@ -28,6 +28,7 @@ import android.net.Uri
 import android.os.Build
 import android.os.Bundle
 import android.provider.MediaStore
+import android.text.InputFilter
 import android.text.Spanned
 import android.text.style.URLSpan
 import android.view.KeyEvent
@@ -74,6 +75,7 @@ import app.pachli.components.compose.dialog.showAddPollDialog
 import app.pachli.components.compose.view.ComposeOptionsListener
 import app.pachli.components.compose.view.ComposeScheduleView
 import app.pachli.components.instanceinfo.InstanceInfoRepository
+import app.pachli.core.common.string.mastodonLength
 import app.pachli.core.database.model.AccountEntity
 import app.pachli.core.navigation.ComposeActivityIntent
 import app.pachli.core.navigation.ComposeActivityIntent.ComposeOptions
@@ -1323,6 +1325,7 @@ class ComposeActivity :
          *   (https://docs.joinmastodon.org/user/posting/#mentions)
          * - Hashtags are always treated as their actual length, including the "#"
          *   (https://docs.joinmastodon.org/user/posting/#hashtags)
+         * - Emojis are treated as a single character
          *
          * Content warning text is always treated as its full length, URLs and other entities
          * are not treated differently.
@@ -1332,9 +1335,8 @@ class ComposeActivity :
          * @param urlLength the number of characters attributed to URLs
          * @return the effective status length
          */
-        @JvmStatic
         fun statusLength(body: Spanned, contentWarning: Spanned?, urlLength: Int): Int {
-            var length = body.length - body.getSpans(0, body.length, URLSpan::class.java)
+            var length = body.toString().mastodonLength() - body.getSpans(0, body.length, URLSpan::class.java)
                 .fold(0) { acc, span ->
                     // Accumulate a count of characters to be *ignored* in the final length
                     acc + when (span) {
@@ -1347,15 +1349,50 @@ class ComposeActivity :
                         }
                         else -> {
                             // Expected to be negative if the URL length < maxUrlLength
-                            span.url.length - urlLength
+                            span.url.mastodonLength() - urlLength
                         }
                     }
                 }
 
             // Content warning text is treated as is, URLs or mentions there are not special
-            contentWarning?.let { length += it.length }
+            contentWarning?.let { length += it.toString().mastodonLength() }
 
             return length
         }
+
+        /**
+         * [InputFilter] that uses the "Mastodon" length of a string, where emojis always
+         * count as a single character.
+         *
+         * Unlike [InputFilter.LengthFilter] the source input is not trimmed if it is
+         * too long, it's just rejected.
+         */
+        class MastodonLengthFilter(private val maxLength: Int) : InputFilter {
+            override fun filter(
+                source: CharSequence?,
+                start: Int,
+                end: Int,
+                dest: Spanned?,
+                dstart: Int,
+                dend: Int,
+            ): CharSequence? {
+                val destRemovedLength = dest?.subSequence(dstart, dend).toString().mastodonLength()
+                val available = maxLength - dest.toString().mastodonLength() + destRemovedLength
+                val sourceLength = source?.subSequence(start, end).toString().mastodonLength()
+
+                // Not enough space to insert the new text
+                if (sourceLength > available) return REJECT
+
+                return ALLOW
+            }
+
+            companion object {
+                /** Filter result allowing the changes */
+                val ALLOW = null
+
+                /** Filter result preventing the changes */
+                const val REJECT = ""
+            }
+        }
     }
 }

app/src/main/java/app/pachli/components/compose/dialog/AddPollOptionsAdapter.kt

@@ -16,13 +16,13 @@
 
 package app.pachli.components.compose.dialog
 
-import android.text.InputFilter
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.core.widget.doOnTextChanged
 import androidx.recyclerview.widget.RecyclerView
 import app.pachli.R
+import app.pachli.components.compose.ComposeActivity.Companion.MastodonLengthFilter
 import app.pachli.databinding.ItemAddPollOptionBinding
 import app.pachli.util.BindingHolder
 import app.pachli.util.visible
@@ -45,7 +45,7 @@ class AddPollOptionsAdapter(
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BindingHolder<ItemAddPollOptionBinding> {
         val binding = ItemAddPollOptionBinding.inflate(LayoutInflater.from(parent.context), parent, false)
         val holder = BindingHolder(binding)
-        binding.optionEditText.filters = arrayOf(InputFilter.LengthFilter(maxOptionLength))
+        binding.optionEditText.filters = arrayOf(MastodonLengthFilter(maxOptionLength))
 
         binding.optionEditText.doOnTextChanged { s, _, _, _ ->
             val pos = holder.bindingAdapterPosition

app/src/test/java/app/pachli/SpanUtilsTest.kt

@@ -1,6 +1,6 @@
 package app.pachli
 
-import android.text.Spannable
+import app.pachli.core.testing.fakes.FakeSpannable
 import app.pachli.util.highlightSpans
 import org.junit.Assert
 import org.junit.Test
@@ -127,55 +127,4 @@ class SpanUtilsTest {
             Assert.assertEquals(expectedEndIndex, span.end)
         }
     }
-
-    class FakeSpannable(private val text: String) : Spannable {
-        val spans = mutableListOf<BoundedSpan>()
-
-        override fun setSpan(what: Any?, start: Int, end: Int, flags: Int) {
-            spans.add(BoundedSpan(what, start, end))
-        }
-
-        override fun <T : Any> getSpans(start: Int, end: Int, type: Class<T>): Array<T> {
-            return spans.filter { it.start >= start && it.end <= end && type.isInstance(it.span) }
-                .map { it.span }
-                .toTypedArray() as Array<T>
-        }
-
-        override fun removeSpan(what: Any?) {
-            spans.removeIf { span -> span.span == what }
-        }
-
-        override fun toString(): String {
-            return text
-        }
-
-        override val length: Int
-            get() = text.length
-
-        class BoundedSpan(val span: Any?, val start: Int, val end: Int)
-
-        override fun nextSpanTransition(start: Int, limit: Int, type: Class<*>?): Int {
-            throw NotImplementedError()
-        }
-
-        override fun getSpanEnd(tag: Any?): Int {
-            throw NotImplementedError()
-        }
-
-        override fun getSpanFlags(tag: Any?): Int {
-            throw NotImplementedError()
-        }
-
-        override fun get(index: Int): Char {
-            throw NotImplementedError()
-        }
-
-        override fun subSequence(startIndex: Int, endIndex: Int): CharSequence {
-            throw NotImplementedError()
-        }
-
-        override fun getSpanStart(tag: Any?): Int {
-            throw NotImplementedError()
-        }
-    }
 }

app/src/test/java/app/pachli/components/compose/ComposeActivityTest.kt

@@ -238,6 +238,49 @@ class ComposeActivityTest {
         }
     }
 
+    @Test
+    fun whenTextContainsEmoji_emojisAreCountedAsOneCharacter() {
+        val content = "Test 😜"
+        rule.launch()
+        rule.getScenario().onActivity {
+            insertSomeTextInContent(it, content)
+            assertEquals(6, it.calculateTextLength())
+        }
+    }
+
+    @Test
+    fun whenTextContainsConesecutiveEmoji_emojisAreCountedAsSeparateCharacters() {
+        val content = "Test 😜😜"
+        rule.launch()
+        rule.getScenario().onActivity {
+            insertSomeTextInContent(it, content)
+            assertEquals(7, it.calculateTextLength())
+        }
+    }
+
+    @Test
+    fun whenTextContainsUrlWithEmoji_ellipsizedUrlIsCountedCorrectly() {
+        val content = "https://🤪.com"
+        rule.launch()
+        rule.getScenario().onActivity {
+            insertSomeTextInContent(it, content)
+            assertEquals(
+                InstanceInfoRepository.DEFAULT_CHARACTERS_RESERVED_PER_URL,
+                it.calculateTextLength(),
+            )
+        }
+    }
+
+    @Test
+    fun whenTextContainsNonEnglishCharacters_lengthIsCountedCorrectly() {
+        val content = "こんにちは. General Kenobi" // "Hello there. General Kenobi"
+        rule.launch()
+        rule.getScenario().onActivity {
+            insertSomeTextInContent(it, content)
+            assertEquals(21, it.calculateTextLength())
+        }
+    }
+
     @Test
     fun whenTextContainsUrl_onlyEllipsizedURLIsCounted() {
         val url = "https://www.google.dk/search?biw=1920&bih=990&tbm=isch&sa=1&ei=bmDrWuOoKMv6kwWOkIaoDQ&q=indiana+jones+i+hate+snakes+animated&oq=indiana+jones+i+hate+snakes+animated&gs_l=psy-ab.3...54174.55443.0.55553.9.7.0.0.0.0.255.333.1j0j1.2.0....0...1c.1.64.psy-ab..7.0.0....0.40G-kcDkC6A#imgdii=PSp15hQjN1JqvM:&imgrc=H0hyE2JW5wrpBM:"

app/src/test/java/app/pachli/components/compose/MastodonLengthFilterTest.kt

@@ -0,0 +1,169 @@
+/*
+ * Copyright 2023 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.components.compose
+
+import app.pachli.components.compose.ComposeActivity.Companion.MastodonLengthFilter
+import app.pachli.components.compose.ComposeActivity.Companion.MastodonLengthFilter.Companion.ALLOW
+import app.pachli.components.compose.ComposeActivity.Companion.MastodonLengthFilter.Companion.REJECT
+import app.pachli.core.testing.fakes.FakeSpannable
+import com.google.common.truth.Truth.assertThat
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.Parameterized
+import org.junit.runners.Parameterized.Parameters
+
+/**
+ * Parameters to pass to [MastodonLengthFilter.filter] and the expected result.
+ */
+data class TestData(
+    val source: CharSequence?,
+    val start: Int,
+    val end: Int,
+    val dest: String,
+    val dstart: Int,
+    val dend: Int,
+    /** The expected result */
+    val want: String?,
+)
+
+@RunWith(Parameterized::class)
+class MastodonLengthFilterTest(private val testData: TestData) {
+    companion object {
+        @Parameters(name = "{0}")
+        @JvmStatic
+        fun data(): Iterable<TestData> {
+            return listOf(
+                // Inserting 9 characters to empty string
+                TestData(
+                    "some text",
+                    0,
+                    9,
+                    "",
+                    0,
+                    0,
+                    ALLOW,
+                ),
+                // Appending 1 character to length 5 string
+                TestData(
+                    "6",
+                    0,
+                    1,
+                    "12345",
+                    0,
+                    5,
+                    ALLOW,
+                ),
+                // Replacing 1 character in middle of length 5 string
+                TestData(
+                    "x",
+                    0,
+                    1,
+                    "12345",
+                    2,
+                    3,
+                    ALLOW,
+                ),
+                // Replacing all characters in length 5 string
+                TestData(
+                    "xxxxx",
+                    0,
+                    4,
+                    "12345",
+                    0,
+                    4,
+                    ALLOW,
+                ),
+                // Deleting characters with a zero-length replacement
+                TestData(
+                    "",
+                    0,
+                    0,
+                    "12345",
+                    0,
+                    3,
+                    ALLOW,
+                ),
+                // Appending a 2 character emoji to a 9 character string
+                TestData(
+                    "😜",
+                    0,
+                    2,
+                    "123456789",
+                    9,
+                    9,
+                    ALLOW,
+                ),
+                // Extending a 10 character string by 1
+                TestData(
+                    "x",
+                    0,
+                    1,
+                    "1234567890",
+                    10,
+                    10,
+                    REJECT,
+                ),
+                // Extending a 9 character string by 2
+                TestData(
+                    "xx",
+                    0,
+                    2,
+                    "123456789",
+                    9,
+                    9,
+                    REJECT,
+                ),
+                // Replacing 2 characters in a 10 character string with 3
+                TestData(
+                    "xxx",
+                    0,
+                    3,
+                    "1234567890",
+                    5,
+                    7,
+                    REJECT,
+                ),
+                // Appending 2 x 2 character emojis to a 9 character string
+                TestData(
+                    "😜😜",
+                    0,
+                    3,
+                    "123456789",
+                    9,
+                    9,
+                    REJECT,
+                ),
+            )
+        }
+    }
+
+    @Test
+    fun filter_matchesExpectations() {
+        val filter = MastodonLengthFilter(10)
+        assertThat(
+            filter.filter(
+                testData.source,
+                testData.start,
+                testData.end,
+                FakeSpannable(testData.dest),
+                testData.dstart,
+                testData.dend,
+            ),
+        ).isEqualTo(testData.want)
+    }
+}

app/src/test/java/app/pachli/components/compose/StatusLengthTest.kt

@@ -17,7 +17,7 @@
 
 package app.pachli.components.compose
 
-import app.pachli.SpanUtilsTest
+import app.pachli.core.testing.fakes.FakeSpannable
 import app.pachli.util.highlightSpans
 import org.junit.Assert.assertEquals
 import org.junit.Test
@@ -53,7 +53,7 @@ class StatusLengthTest(
 
     @Test
     fun statusLength_matchesExpectations() {
-        val spannedText = SpanUtilsTest.FakeSpannable(text)
+        val spannedText = FakeSpannable(text)
         highlightSpans(spannedText, 0)
 
         assertEquals(
@@ -64,10 +64,10 @@ class StatusLengthTest(
 
     @Test
     fun statusLength_withCwText_matchesExpectations() {
-        val spannedText = SpanUtilsTest.FakeSpannable(text)
+        val spannedText = FakeSpannable(text)
         highlightSpans(spannedText, 0)
 
-        val cwText = SpanUtilsTest.FakeSpannable(
+        val cwText = FakeSpannable(
             "a @example@example.org #hashtagmention and http://example.org URL",
         )
         assertEquals(

core/common/src/main/kotlin/app/pachli/core/common/string/StringUtils.kt

@@ -1,6 +1,7 @@
 package app.pachli.core.common.string
 
 import android.text.Spanned
+import java.text.BreakIterator
 import java.util.Random
 
 private const val POSSIBLE_CHARS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
@@ -44,6 +45,20 @@ fun String.isLessThanOrEqual(other: String): Boolean {
     return this == other || isLessThan(other)
 }
 
+/**
+ * @return the "Mastodon" length of a string. [String.length] counts emojis as
+ * multiple characters, but Mastodon treats them as a single character.
+ */
+fun String.mastodonLength(): Int {
+    val breakIterator = BreakIterator.getCharacterInstance()
+    breakIterator.setText(this)
+    var count = 0
+    while (breakIterator.next() != BreakIterator.DONE) {
+        count++
+    }
+    return count
+}
+
 fun Spanned.trimTrailingWhitespace(): Spanned {
     var i = length
     do {

core/testing/lint-baseline.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<issues format="6" by="lint 8.1.2" type="baseline" client="gradle" dependencies="false" name="AGP (8.1.2)" variant="all" version="8.1.2">
+<issues format="6" by="lint 8.2.0" type="baseline" client="gradle" dependencies="false" name="AGP (8.2.0)" variant="all" version="8.2.0">
 
     <issue
         id="InvalidPackage"
@@ -71,6 +71,17 @@
             file="$GRADLE_USER_HOME/caches/modules-2/files-2.1/org.robolectric/utils/4.11.1/12828864aac49e8ebcf2de03d3d33919ca8a1b01/utils-4.11.1.jar"/>
     </issue>
 
+    <issue
+        id="NewApi"
+        message="Call requires API level 24 (current min is 23): `java.util.Collection#removeIf`"
+        errorLine1="        spans.removeIf { span -> span.span == what }"
+        errorLine2="              ~~~~~~~~">
+        <location
+            file="src/main/kotlin/app/pachli/core/testing/fakes/FakeSpannable.kt"
+            line="36"
+            column="15"/>
+    </issue>
+
     <issue
         id="NewApi"
         message="Call requires API level 24 (current min is 23): `java.util.Map#getOrDefault`"

core/testing/src/main/kotlin/app/pachli/core/testing/fakes/FakeSpannable.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2023 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.testing.fakes
+
+import android.text.Spannable
+
+class FakeSpannable(private val text: String) : Spannable {
+    val spans = mutableListOf<BoundedSpan>()
+
+    override fun setSpan(what: Any?, start: Int, end: Int, flags: Int) {
+        spans.add(BoundedSpan(what, start, end))
+    }
+
+    override fun <T : Any> getSpans(start: Int, end: Int, type: Class<T>): Array<T> {
+        return spans.filter { it.start >= start && it.end <= end && type.isInstance(it.span) }
+            .map { it.span }
+            .toTypedArray() as Array<T>
+    }
+
+    override fun removeSpan(what: Any?) {
+        spans.removeIf { span -> span.span == what }
+    }
+
+    override fun toString(): String {
+        return text
+    }
+
+    override val length: Int
+        get() = text.length
+
+    class BoundedSpan(val span: Any?, val start: Int, val end: Int)
+
+    override fun nextSpanTransition(start: Int, limit: Int, type: Class<*>?): Int {
+        throw NotImplementedError()
+    }
+
+    override fun getSpanEnd(tag: Any?): Int {
+        throw NotImplementedError()
+    }
+
+    override fun getSpanFlags(tag: Any?): Int {
+        throw NotImplementedError()
+    }
+
+    override fun get(index: Int): Char {
+        throw NotImplementedError()
+    }
+
+    override fun subSequence(startIndex: Int, endIndex: Int): CharSequence {
+        return text.subSequence(startIndex, endIndex)
+    }
+
+    override fun getSpanStart(tag: Any?): Int {
+        throw NotImplementedError()
+    }
+}