adding tests around the event html rendering

- the test helper is a little hacky in order to covert the spans to something human readable

vector/src/androidTest/java/im/vector/app/core/utils/TestSpan.kt

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * 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
+ *
+ *     http://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 im.vector.app.core.utils
+
+import android.graphics.Canvas
+import android.graphics.Paint
+import android.text.Layout
+import android.text.Spannable
+import androidx.core.text.getSpans
+import im.vector.app.features.html.HtmlCodeSpan
+import io.mockk.justRun
+import io.mockk.mockk
+import io.mockk.slot
+import io.mockk.verify
+import io.noties.markwon.core.spans.EmphasisSpan
+import io.noties.markwon.core.spans.OrderedListItemSpan
+import io.noties.markwon.core.spans.StrongEmphasisSpan
+
+fun Spannable.toTestSpan(): String {
+    var output = toString()
+    readSpansWithContent().forEach {
+        val tags = it.span.readTags()
+        val remappedContent = it.span.remapContent(source = this, originalContent = it.content)
+        output = output.replace(it.content, "${tags.open}$remappedContent${tags.close}")
+    }
+    return output
+}
+
+private fun Spannable.readSpansWithContent() = getSpans<Any>().map { span ->
+    val start = getSpanStart(span)
+    val end = getSpanEnd(span)
+    SpanWithContent(
+            content = substring(start, end),
+            span = span
+    )
+}.reversed()
+
+private fun Any.readTags(): SpanTags {
+    return when (this::class) {
+        OrderedListItemSpan::class -> SpanTags("[list item]", "[/list item]")
+        HtmlCodeSpan::class -> SpanTags("[code]", "[/code]")
+        StrongEmphasisSpan::class -> SpanTags("[bold]", "[/bold]")
+        EmphasisSpan::class -> SpanTags("[italic]", "[/italic]")
+        else -> throw IllegalArgumentException("Unknown ${this::class}")
+    }
+}
+
+private fun Any.remapContent(source: CharSequence, originalContent: String): String {
+    return when (this::class) {
+        OrderedListItemSpan::class -> {
+            val prefix = (this as OrderedListItemSpan).collectNumber(source)
+            "$prefix$originalContent"
+        }
+        else -> originalContent
+    }
+}
+
+private fun OrderedListItemSpan.collectNumber(text: CharSequence): String {
+    val fakeCanvas = mockk<Canvas>()
+    val fakeLayout = mockk<Layout>()
+    justRun { fakeCanvas.drawText(any(), any(), any(), any()) }
+    val paint = Paint()
+    drawLeadingMargin(fakeCanvas, paint, 0, 0, 0, 0, 0, text, 0, text.length - 1, true, fakeLayout)
+    val slot = slot<String>()
+    verify { fakeCanvas.drawText(capture(slot), any(), any(), any()) }
+    return slot.captured
+}
+
+private data class SpanTags(
+        val open: String,
+        val close: String,
+)
+
+private data class SpanWithContent(
+        val content: String,
+        val span: Any
+)

vector/src/androidTest/java/im/vector/app/features/html/EventHtmlRendererTest.kt

@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * 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
+ *
+ *     http://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 im.vector.app.features.html
+
+import androidx.core.text.toSpannable
+import androidx.test.platform.app.InstrumentationRegistry
+import im.vector.app.core.resources.ColorProvider
+import im.vector.app.core.utils.toTestSpan
+import im.vector.app.features.settings.VectorPreferences
+import io.mockk.every
+import io.mockk.mockk
+import org.amshove.kluent.shouldBeEqualTo
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+import kotlin.text.Typography.nbsp
+
+@RunWith(JUnit4::class)
+class EventHtmlRendererTest {
+
+    private val context = InstrumentationRegistry.getInstrumentation().targetContext
+    private val fakeVectorPreferences = mockk<VectorPreferences>().also {
+        every { it.latexMathsIsEnabled() } returns false
+    }
+
+    private val renderer = EventHtmlRenderer(
+            MatrixHtmlPluginConfigure(ColorProvider(context), context.resources),
+            context,
+            fakeVectorPreferences
+    )
+
+    @Test
+    fun takesInitialListPositionIntoAccount() {
+        val result = """<ol start="5"><li>first entry<li></ol>""".renderAsTestSpan()
+
+        result shouldBeEqualTo "[list item]5.${nbsp}first entry[/list item]\n"
+    }
+
+    @Test
+    fun doesNotProcessMarkdownWithinCodeBlocks() {
+        val result = """<code>__italic__ **bold**</code>""".renderAsTestSpan()
+
+        result shouldBeEqualTo "[code]__italic__ **bold**[/code]"
+    }
+
+    @Test
+    fun doesNotProcessMarkdownBoldAndItalic() {
+        val result = """__italic__ **bold**""".renderAsTestSpan()
+
+        result shouldBeEqualTo "__italic__ **bold**"
+    }
+
+    @Test
+    fun processesHtmlWithinCodeBlocks() {
+        val result = """<code><i>italic</i> <b>bold</b></code>""".renderAsTestSpan()
+
+        result shouldBeEqualTo "[code][italic]italic[/italic] [bold]bold[/bold][/code]"
+    }
+
+    private fun String.renderAsTestSpan() = renderer.render(this).toSpannable().toTestSpan()
+}