Merge branch 'main' into docs/instrumented-tests-correction

Say in tests what the file card says when it does not know

CLAUDE.md

@@ -64,16 +64,28 @@ of the first one that fails.
 on this machine (below), so without it an androidTest compile error is not discovered until CI.
 ktlint and detekt also cover the `test`/`androidTest` source sets that `lintDebug` skips.
 
-## Instrumented tests do not run locally
+## Instrumented tests: where they actually run
 
-Two independent reasons, so do not spend time on either:
+This section said the opposite until 2026-08-24, and both of its claims had been false for two
+days. Read it as the current answer, and see the git history if you need the old one.
 
-- **Emulators segfault on this host.** qemu dies on every AVD. Instrumented tests run on CI or on
-  the physical Pixel, never in a local emulator.
-- **The API 37 image is broken.** `android-37.0` crash-loops surfaceflinger inside its own gralloc
-  mapper, so every test fails there regardless of this app. `docs/api-37-emulator-crash.md` records
-  the evidence and the ruled-out fixes; CI's matrix therefore stops at API 36 even though targetSdk
-  is 37. **API 37 needs a manual check on the Pixel 10 Pro XL before each release.**
+- **Local emulators work, for API 33-36.** `tools/local-emulator/run-e2e.sh` runs them on this
+  host. The segfault that made this look impossible was not a broken machine: SwiftShader's Reactor
+  JIT writes generated shader code onto the heap and executes it, Fedora's SELinux policy denies
+  `execheap`, and qemu dies. Choosing a different renderer avoids it entirely — `-gpu host`,
+  `angle_indirect` and `swangle_indirect` all boot, while `auto`, `off`, `guest` and
+  `swiftshader_indirect` do not. `docs/local-emulator.md` has the evidence and the per-API renderer
+  table.
+- **CI runs API 37, and it gates.** The matrix is 33/34/35/36/37. Two Media3 hardware-transcode
+  tests fail inside the emulator's own `c2.goldfish.h264.decoder` rather than on anything this app
+  does; they carry `@FailsOnEmulatorApi37` and run in a separate `continue-on-error` job,
+  `E2E API 37 Media3 hardware transcode (advisory)`. The gating leg runs the other 55.
+  **That advisory job is red on every PR, by design** — do not read it as your change breaking
+  something, and do not read a green run as evidence those two tests pass.
+  `docs/api-37-emulator-crash.md` has the measurements.
+
+Still true, and the reason the advisory job is not simply deleted: **API 37 needs a manual check on
+the Pixel 10 Pro XL before each release.** The advisory pair is the one thing CI cannot answer for.
 
 On a device or emulator, build only the ABI it can execute:
 
@@ -112,9 +124,9 @@ install for code that can never run — and on API 37 the full APK does not fit
     documents the reasoning — turns "needs a device" into "a pure function plus a thin edge".
     Robolectric is in the JVM source set, `compose-ui-test-junit4` with it, so Compose screens are
     unit testable too. Reach for the seam before concluding something cannot be unit tested.
-  - **E2E is runnable locally now.** `tools/local-emulator/run-e2e.sh` runs API 33-36 on this
-    machine; see `docs/local-emulator.md`. That was believed impossible until the SELinux/renderer
-    cause was found, and it is what makes the e2e half of this norm enforceable.
+  - **E2E is runnable locally**, API 33-36, via `tools/local-emulator/run-e2e.sh` — see
+    "Instrumented tests: where they actually run" above. That was believed impossible until the
+    SELinux/renderer cause was found, and it is what makes the e2e half of this norm enforceable.
   - **A test has to bite.** Revert the line it covers, confirm it goes red, restore. A review of
     this codebase ran 46 mutations against a 257-test suite and **9 were vacuous** — five of them
     passing the whole suite over a completely unguarded code path. Green is not evidence.

app/src/test/java/org/libremediaconverter/convert/AdvancedPanelSavedStateTest.kt

@@ -0,0 +1,159 @@
+package org.libremediaconverter.convert
+
+import android.os.Bundle
+import android.os.Parcel
+import android.os.Parcelable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.saveable.LocalSaveableStateRegistry
+import androidx.compose.runtime.saveable.SaveableStateRegistry
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.performClick
+import androidx.media3.common.util.UnstableApi
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.libremediaconverter.createDrainedComposeRule
+import org.libremediaconverter.model.AudioCodec
+import org.libremediaconverter.model.Container
+import org.libremediaconverter.model.OutputSpec
+import org.libremediaconverter.model.Validation
+import org.libremediaconverter.model.VideoCodec
+import org.libremediaconverter.ui.TestTags
+import org.robolectric.RobolectricTestRunner
+
+/**
+ * What `AdvancedPickerTest`'s restoration test cannot see.
+ *
+ * `StateRestorationTester` saves into an **in-memory map**, never a `Bundle`. That is enough to
+ * discriminate `rememberSaveable` from `remember`, and it is where it stops: the map holds object
+ * references, so a value the platform could never parcel goes in and comes back out looking green.
+ * `AppRootRestorationTest` has the same blind spot and `DestinationSaverTest` is the split it
+ * prompted; this is that split for `expanded`, the only `rememberSaveable` on either screen's
+ * leaves.
+ *
+ * ### The saved representation is not the Boolean
+ *
+ * `var expanded by rememberSaveable { mutableStateOf(false) }` passes no `stateSaver`, so
+ * `autoSaver` saves **the `MutableState` itself**, not the `false` inside it. That works only
+ * because `mutableStateOf` on Android returns a `Parcelable` implementation -- the same call on a
+ * plain JVM returns one that is not. So what stands between an open panel and a rotation that
+ * closes it is a platform-specific detail of a factory function nothing here names directly, and
+ * an in-memory map cannot tell the two apart.
+ *
+ * Pinning it is the move `DestinationSaverTest` makes about names versus ordinals. Passing an
+ * explicit `stateSaver` would save a bare `Boolean` instead and is a perfectly reasonable edit --
+ * it is just not the one in the tree, and it should be made on purpose rather than discovered
+ * after a rotation.
+ *
+ * ### Shared bite, stated rather than implied
+ *
+ * `rememberSaveable` -> `remember` empties the registry, so it reddens this file *and* the
+ * restoration test in `AdvancedPickerTest`. Both failures belong in any report of that mutation.
+ */
+@UnstableApi
+@RunWith(RobolectricTestRunner::class)
+class AdvancedPanelSavedStateTest {
+
+    // Not `createComposeRule()` directly: see [drainEscapedCoroutineErrors].
+    @get:Rule
+    val composeRule = createDrainedComposeRule()
+
+    /**
+     * `canBeSaved = { true }` deliberately.
+     *
+     * A predicate mirroring what a `Bundle` accepts would be a hand-written copy of the thing
+     * under test, and a `false` from it *drops* the entry silently -- so the test would fail by
+     * finding nothing saved, which is also how a `remember` regression fails. Two causes, one
+     * symptom, is not a test. The type is checked on the way out instead.
+     */
+    private val registry = SaveableStateRegistry(restoredValues = null, canBeSaved = { true })
+
+    @Test
+    fun `the panel registers its open state with the registry, and nothing else`() {
+        setPicker()
+
+        // Collapsed is a saved value, not an absent one: `rememberSaveable` registers its provider
+        // on first composition, whatever the state happens to be. Exactly one, because `expanded`
+        // is the only saveable in the subtree -- a second would mean something else began saving.
+        assertEquals(1, savedValues().size)
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        val saved = theOneSavedValue()
+        assertTrue("saved as ${saved?.javaClass?.name}", saved is MutableState<*>)
+        assertEquals(true, (saved as MutableState<*>).value)
+    }
+
+    @Test
+    fun `the open panel survives a real Parcel, not just an in-memory map`() {
+        setPicker()
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        val saved = theOneSavedValue()
+
+        // The claim the restoration test cannot make. A `MutableState` that was not `Parcelable`
+        // would satisfy `StateRestorationTester` and then be dropped by the platform.
+        assertTrue("saved as ${saved?.javaClass?.name}", saved is Parcelable)
+
+        val restored = throughARealBundle(saved as Parcelable)
+
+        assertTrue("restored as ${restored.javaClass.name}", restored is MutableState<*>)
+        assertEquals(true, (restored as MutableState<*>).value)
+    }
+
+    private fun setPicker() {
+        composeRule.setContent {
+            CompositionLocalProvider(LocalSaveableStateRegistry provides registry) {
+                AdvancedPicker(
+                    spec = OutputSpec(Container.MP4, VideoCodec.H264, AudioCodec.AAC),
+                    validation = Validation.Valid,
+                    onContainer = {},
+                    onVideoCodec = {},
+                    onAudioCodec = {},
+                    onSuggestion = {},
+                )
+            }
+        }
+    }
+
+    /** Every value the picker hands the host to persist, keys dropped -- they are positional. */
+    private fun savedValues(): List<Any?> = composeRule.runOnIdle { registry.performSave().values.flatten() }
+
+    /**
+     * The single saved value, asserted rather than assumed.
+     *
+     * `single()` on an empty list throws `NoSuchElementException: List is empty`, which names
+     * neither the panel nor the registry -- and an empty registry is exactly how the
+     * `rememberSaveable` -> `remember` regression shows up here.
+     */
+    private fun theOneSavedValue(): Any? {
+        val values = savedValues()
+        assertEquals("the panel should register exactly one saved value", 1, values.size)
+        return values.first()
+    }
+
+    /** A write and a read through a real `Parcel`, which is what the tester's map stands in for. */
+    private fun throughARealBundle(value: Parcelable): Parcelable {
+        val bundle = Bundle().apply { putParcelable(KEY, value) }
+        val parcel = Parcel.obtain()
+        return try {
+            parcel.writeBundle(bundle)
+            parcel.setDataPosition(0)
+            val restored = requireNotNull(parcel.readBundle(javaClass.classLoader)) {
+                "the Bundle did not survive the Parcel"
+            }
+            requireNotNull(restored.getParcelable(KEY, Parcelable::class.java)) {
+                "the saved state did not survive the Parcel"
+            }
+        } finally {
+            parcel.recycle()
+        }
+    }
+
+    private companion object {
+        const val KEY = "expanded"
+    }
+}

app/src/test/java/org/libremediaconverter/convert/AdvancedPickerTest.kt

@@ -0,0 +1,321 @@
+package org.libremediaconverter.convert
+
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.assertTextEquals
+import androidx.compose.ui.test.hasAnyAncestor
+import androidx.compose.ui.test.hasTestTag
+import androidx.compose.ui.test.hasText
+import androidx.compose.ui.test.junit4.StateRestorationTester
+import androidx.compose.ui.test.onAllNodesWithTag
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.performClick
+import androidx.media3.common.util.UnstableApi
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.libremediaconverter.createDrainedComposeRule
+import org.libremediaconverter.model.AudioCodec
+import org.libremediaconverter.model.Container
+import org.libremediaconverter.model.ContainerCapabilities
+import org.libremediaconverter.model.InputProbe
+import org.libremediaconverter.model.OutputSpec
+import org.libremediaconverter.model.Validation
+import org.libremediaconverter.model.VideoCodec
+import org.libremediaconverter.ui.TestTags
+import org.robolectric.RobolectricTestRunner
+
+/**
+ * The gate over the Advanced chips, and the error card that deliberately sits outside it.
+ *
+ * Two defects, and they pull in opposite directions.
+ *
+ * The first is the chips escaping the gate, or never being reachable through it. `AdvancedPicker`
+ * is the one leaf on this screen that is not stateless -- `expanded` is its own `rememberSaveable`
+ * -- and Container, Video and Audio live inside `AnimatedVisibility(visible = expanded)`. Nothing
+ * else on the screen hides anything, so a refactor that flattened the panel, or wired the toggle to
+ * a state nobody reads, would render an app that looks reasonable in a screenshot and is wrong.
+ *
+ * The second is the opposite mistake, and it is the one this file exists for: **moving the
+ * `ValidationError` call inside the `AnimatedVisibility`**. It is invoked after that block, so an
+ * invalid spec explains itself and offers one-tap fixes *while the section is collapsed*. That is
+ * the only route out of an invalid spec for a user who never opened Advanced -- and since the only
+ * way to reach an invalid spec is through Advanced, hiding the way out behind the same toggle looks
+ * locally sensible and is a trap. Tidying the two `if` blocks into one is a plausible edit, it
+ * compiles, and until this file existed nothing went red. Every assertion about the error card here
+ * therefore runs with the toggle untouched, and asserts the panel is absent in the same test, so a
+ * future `expanded = true` default cannot quietly satisfy it either.
+ *
+ * The invalid specs come from [ContainerCapabilities.validate] rather than from a hand-built
+ * [Validation.Invalid], so the messages and the suggestions are the real pairing. A hand-built one
+ * would keep passing after `validate` stopped producing anything like it.
+ *
+ * Node location is by the three separate chip-row tags, never by text. `"Copy"` and `"None"` are
+ * each both a [VideoCodec] and an [AudioCodec], and `"MP3"` and `"FLAC"` are each both a
+ * [Container] and an [AudioCodec], so a text matcher over the open panel is ambiguous for four
+ * chips -- which is what the separate tags are for.
+ */
+@UnstableApi
+@RunWith(RobolectricTestRunner::class)
+class AdvancedPickerTest {
+
+    // Not `createComposeRule()` directly: see [drainEscapedCoroutineErrors].
+    @get:Rule
+    val composeRule = createDrainedComposeRule()
+
+    private val restoration = StateRestorationTester(composeRule)
+
+    private val containers = mutableListOf<Container>()
+    private val videoCodecs = mutableListOf<VideoCodec>()
+    private val audioCodecs = mutableListOf<AudioCodec>()
+    private val applied = mutableListOf<OutputSpec>()
+
+    // --- the expand gate ----------------------------------------------------
+
+    @Test
+    fun `the three chip rows appear only while the panel is expanded`() {
+        setPicker()
+
+        assertPanelHidden()
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_PANEL).assertExists()
+        ROW_TAGS.forEach { composeRule.onNodeWithTag(it).assertExists() }
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        // The exit transition outlives the click, so absence has to be waited for rather than
+        // asserted straight away -- unlike the initial collapsed state, which has no animation
+        // in flight.
+        composeRule.waitUntil { nodeCount(TestTags.Converter.ADVANCED_PANEL) == 0 }
+        assertPanelHidden()
+    }
+
+    /** The toggle is the only affordance the collapsed picker offers, so it has to say so. */
+    @Test
+    fun `the toggle names the direction it will move in`() {
+        setPicker()
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).assertTextEquals("Advanced")
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE)
+            .assertTextEquals("Hide advanced")
+    }
+
+    /**
+     * The four colliding labels, one per row.
+     *
+     * `"Copy"` is a video codec *and* an audio codec; `"MP3"` is a container *and* an audio codec.
+     * Clicking each through its own row is what proves the rows are wired to different callbacks
+     * -- a picker that handed every chip to `onAudioCodec` would look identical on screen.
+     */
+    @Test
+    fun `each chip row reports to its own callback, including the labels that collide`() {
+        setPicker()
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        chipIn(TestTags.Converter.ADVANCED_VIDEO_CHIPS, "Copy").performClick()
+
+        assertEquals(listOf(VideoCodec.COPY), videoCodecs)
+        assertEquals(emptyList<AudioCodec>(), audioCodecs)
+
+        chipIn(TestTags.Converter.ADVANCED_AUDIO_CHIPS, "Copy").performClick()
+
+        assertEquals(listOf(AudioCodec.COPY), audioCodecs)
+
+        chipIn(TestTags.Converter.ADVANCED_CONTAINER_CHIPS, "MP3").performClick()
+
+        assertEquals(listOf(Container.MP3), containers)
+        // Still only the one audio click. `MP3` is an AudioCodec label too, and the container row
+        // must not be reporting through that callback.
+        assertEquals(listOf(AudioCodec.COPY), audioCodecs)
+    }
+
+    // --- the error card, which is outside the gate --------------------------
+
+    /**
+     * The headline case. Dropping both tracks is reachable from the collapsed screen -- the
+     * `None`/`None` pair is set inside Advanced, but the user can close it again -- and the
+     * explanation has to still be there.
+     */
+    @Test
+    fun `an empty output explains itself while the section is collapsed`() {
+        val spec = OutputSpec(Container.MP4, VideoCodec.NONE, AudioCodec.NONE)
+        val invalid = invalidFor(spec)
+
+        assertEquals("This would produce an empty file — keep at least one track.", invalid.message)
+
+        setPicker(spec, invalid)
+
+        assertPanelHidden()
+        composeRule.onNodeWithTag(TestTags.Converter.VALIDATION_ERROR).assertExists()
+        composeRule.onNodeWithText(invalid.message).assertIsDisplayed()
+    }
+
+    @Test
+    fun `a codec the container cannot hold explains itself while the section is collapsed`() {
+        val spec = OutputSpec(Container.WEBM, VideoCodec.H264, AudioCodec.OPUS)
+        val invalid = invalidFor(spec)
+
+        assertEquals("WebM cannot hold H.264 video.", invalid.message)
+
+        setPicker(spec, invalid)
+
+        assertPanelHidden()
+        composeRule.onNodeWithText(invalid.message).assertIsDisplayed()
+    }
+
+    /**
+     * Clicking a suggestion, with the toggle never touched.
+     *
+     * The second suggestion rather than the first, and its count pinned first: with one suggestion
+     * a picker that handed every chip `suggestions[0]` would pass, and `onNodeWithTag` on a
+     * suggestion index that no longer exists reports an unhelpful matcher failure rather than
+     * saying the list shrank.
+     */
+    @Test
+    fun `a suggestion chip applies its own spec without the section ever being opened`() {
+        val spec = OutputSpec(Container.WEBM, VideoCodec.H264, AudioCodec.OPUS)
+        val invalid = invalidFor(spec)
+
+        assertEquals(2, invalid.suggestions.size)
+        val second = invalid.suggestions[1]
+
+        setPicker(spec, invalid)
+
+        assertPanelHidden()
+        composeRule.onNodeWithTag(TestTags.Converter.suggestion(1)).assertTextEquals(describe(second))
+        composeRule.onNodeWithTag(TestTags.Converter.suggestion(1)).performClick()
+
+        assertEquals(listOf(second), applied)
+        // What the chips offer is what `validate` said would work, not a repair of the test's own.
+        assertTrue(
+            "suggestion $second should itself validate",
+            ContainerCapabilities.validate(second, PROBE).isValid,
+        )
+    }
+
+    /** A valid spec has nothing to say, collapsed or not. */
+    @Test
+    fun `a valid spec renders no error card`() {
+        setPicker()
+
+        composeRule.onNodeWithTag(TestTags.Converter.VALIDATION_ERROR).assertDoesNotExist()
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+
+        composeRule.onNodeWithTag(TestTags.Converter.VALIDATION_ERROR).assertDoesNotExist()
+    }
+
+    // --- recreation ---------------------------------------------------------
+
+    /**
+     * `expanded` is the only `rememberSaveable` on either screen's leaves.
+     *
+     * `MainActivity` declares no `configChanges`, so a rotation destroys and rebuilds the whole
+     * composition. A panel the user opened, set three chips in, and left open must not close
+     * itself on the way back. `remember` would.
+     *
+     * What this cannot see is the saved *representation* -- `StateRestorationTester` saves into an
+     * in-memory map rather than a `Bundle`. `AdvancedPanelSavedStateTest` covers that half.
+     */
+    @Test
+    fun `an open panel is still open after recreation`() {
+        restoration.setContent {
+            AdvancedPicker(
+                spec = VALID_SPEC,
+                validation = Validation.Valid,
+                onContainer = {},
+                onVideoCodec = {},
+                onAudioCodec = {},
+                onSuggestion = {},
+            )
+        }
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE).performClick()
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_PANEL).assertExists()
+
+        restoration.emulateSavedInstanceStateRestore()
+
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_PANEL).assertExists()
+        ROW_TAGS.forEach { composeRule.onNodeWithTag(it).assertExists() }
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_TOGGLE)
+            .assertTextEquals("Hide advanced")
+    }
+
+    /** The default has to survive too, or the panel would spring open on every rotation. */
+    @Test
+    fun `a collapsed panel is still collapsed after recreation`() {
+        restoration.setContent {
+            AdvancedPicker(
+                spec = VALID_SPEC,
+                validation = Validation.Valid,
+                onContainer = {},
+                onVideoCodec = {},
+                onAudioCodec = {},
+                onSuggestion = {},
+            )
+        }
+
+        assertPanelHidden()
+
+        restoration.emulateSavedInstanceStateRestore()
+
+        assertPanelHidden()
+    }
+
+    // --- helpers ------------------------------------------------------------
+
+    private fun setPicker(spec: OutputSpec = VALID_SPEC, validation: Validation = Validation.Valid) {
+        composeRule.setContent {
+            AdvancedPicker(
+                spec = spec,
+                validation = validation,
+                onContainer = { containers += it },
+                onVideoCodec = { videoCodecs += it },
+                onAudioCodec = { audioCodecs += it },
+                onSuggestion = { applied += it },
+            )
+        }
+    }
+
+    /** The whole panel, by every tag it owns, so a partial escape counts as a failure. */
+    private fun assertPanelHidden() {
+        composeRule.onNodeWithTag(TestTags.Converter.ADVANCED_PANEL).assertDoesNotExist()
+        ROW_TAGS.forEach { composeRule.onNodeWithTag(it).assertDoesNotExist() }
+    }
+
+    private fun nodeCount(tag: String) = composeRule.onAllNodesWithTag(tag).fetchSemanticsNodes().size
+
+    private fun chipIn(rowTag: String, label: String) =
+        composeRule.onNode(hasText(label) and hasAnyAncestor(hasTestTag(rowTag)))
+
+    private fun invalidFor(spec: OutputSpec): Validation.Invalid {
+        val validation = ContainerCapabilities.validate(spec, PROBE)
+        return validation as? Validation.Invalid
+            ?: throw AssertionError("$spec was expected to be invalid, but validate said $validation")
+    }
+
+    private companion object {
+        val ROW_TAGS = listOf(
+            TestTags.Converter.ADVANCED_CONTAINER_CHIPS,
+            TestTags.Converter.ADVANCED_VIDEO_CHIPS,
+            TestTags.Converter.ADVANCED_AUDIO_CHIPS,
+        )
+
+        val VALID_SPEC = OutputSpec(Container.MP4, VideoCodec.H264, AudioCodec.AAC)
+
+        /** An ordinary H.264/AAC MP4, so the suggestions have a real source to repair towards. */
+        val PROBE = InputProbe(
+            videoCodec = "h264",
+            audioCodec = "aac",
+            durationMs = 90_000,
+            container = Container.MP4,
+        )
+    }
+}

app/src/test/java/org/libremediaconverter/convert/ConverterFormattersTest.kt

@@ -0,0 +1,152 @@
+package org.libremediaconverter.convert
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.libremediaconverter.model.AudioCodec
+import org.libremediaconverter.model.Container
+import org.libremediaconverter.model.EnginePreference
+import org.libremediaconverter.model.OutputSpec
+import org.libremediaconverter.model.VideoCodec
+
+/**
+ * The four pure helpers behind the converter screen's prose, pinned at the points where they
+ * change what they say.
+ *
+ * No Compose rule and no Robolectric: these are `String` in, `String` out, and running them under a
+ * device sandbox would buy nothing while hiding the boundaries in a rendered tree.
+ *
+ * The defect each group bites on:
+ *
+ * - **[formatBytes] picks a unit by comparing against three thresholds.** Every one of them is a
+ *   `>=`, and a `>` would move a file sitting exactly on a boundary into the unit below -- `1 GB`
+ *   shown as `1000.0 MB`. Only a value *on* the threshold can tell the two apart, so each of the
+ *   three is asserted at the boundary and one below it. The unit prefixes are decimal, matching
+ *   what the file manager and the provider report, not powers of two.
+ * - **[formatDuration] has no hours field.** An hour-long recording reads `60:00`, and that is the
+ *   contract rather than an oversight -- the row is a length, not a clock. Pinned so that adding
+ *   hours is a deliberate change with a red test in front of it instead of a silent reformat.
+ * - **[describe] builds the suggestion-chip label out of up to three parts**, and the parts are
+ *   conditional: [VideoCodec.NONE] and [AudioCodec.NONE] drop out entirely, so an image output
+ *   with neither track has to render as the container alone rather than as a container followed
+ *   by a dangling separator.
+ * - **[EnginePreference] carries no `label` property**, unlike every other enum the screen
+ *   renders; its three display strings live in a `when` in the screen file. Adding a constant is
+ *   caught by the compiler because that `when` is exhaustive, but nothing stops two constants
+ *   being given the same string, which is what the distinctness assertion is for.
+ */
+class ConverterFormattersTest {
+
+    @Test
+    fun `bytes below a kilobyte are counted exactly`() {
+        assertEquals("0 B", formatBytes(0))
+        assertEquals("1 B", formatBytes(1))
+        assertEquals("999 B", formatBytes(999))
+    }
+
+    @Test
+    fun `each unit starts exactly on its threshold rather than one byte past it`() {
+        assertEquals("1 kB", formatBytes(1_000))
+        assertEquals("1.0 MB", formatBytes(1_000_000))
+        assertEquals("1.0 GB", formatBytes(1_000_000_000))
+    }
+
+    /**
+     * One byte below each threshold, which is the half a `>=` to `>` change leaves alone. Both
+     * halves are needed: the boundary values alone would still pass if the comparison let
+     * everything through.
+     */
+    @Test
+    fun `a value just below a threshold stays in the smaller unit`() {
+        assertEquals("999 B", formatBytes(999))
+        assertEquals("1000 kB", formatBytes(999_999))
+        assertEquals("1000.0 MB", formatBytes(999_999_999))
+    }
+
+    @Test
+    fun `a real file size reads as one decimal place`() {
+        assertEquals("12.3 MB", formatBytes(12_345_678))
+        assertEquals("1.5 GB", formatBytes(1_500_000_000))
+    }
+
+    @Test
+    fun `a duration is minutes and zero-padded seconds`() {
+        assertEquals("0:00", formatDuration(0))
+        assertEquals("0:01", formatDuration(1_000))
+        assertEquals("0:59", formatDuration(59_000))
+        assertEquals("1:00", formatDuration(60_000))
+        assertEquals("1:30", formatDuration(90_000))
+    }
+
+    /** Sub-second remainders are dropped rather than rounded up into the next second. */
+    @Test
+    fun `a partial second does not become a whole one`() {
+        assertEquals("0:00", formatDuration(999))
+        assertEquals("0:59", formatDuration(59_999))
+    }
+
+    /** No hours field, deliberately: an hour is `60:00` and two hours are `120:00`. */
+    @Test
+    fun `an hour and beyond keeps counting in minutes`() {
+        assertEquals("60:00", formatDuration(3_600_000))
+        assertEquals("61:01", formatDuration(3_661_000))
+        assertEquals("120:00", formatDuration(7_200_000))
+    }
+
+    @Test
+    fun `a spec with both tracks names the container and joins the two codecs`() {
+        assertEquals(
+            "MP4 · H.264 + AAC",
+            describe(OutputSpec(Container.MP4, VideoCodec.H264, AudioCodec.AAC)),
+        )
+    }
+
+    @Test
+    fun `a track set to none is left out instead of being named none`() {
+        assertEquals(
+            "MP3 · MP3",
+            describe(OutputSpec(Container.MP3, VideoCodec.NONE, AudioCodec.MP3)),
+        )
+        assertEquals(
+            "MP4 · H.264",
+            describe(OutputSpec(Container.MP4, VideoCodec.H264, AudioCodec.NONE)),
+        )
+    }
+
+    /** An image output has neither track, so there is nothing for the separator to separate. */
+    @Test
+    fun `a spec with no tracks at all is the container alone, with no trailing separator`() {
+        assertEquals("GIF", describe(OutputSpec(Container.GIF, VideoCodec.NONE, AudioCodec.NONE)))
+        assertEquals(
+            "PNG frames",
+            describe(OutputSpec(Container.IMAGE_SEQUENCE, VideoCodec.NONE, AudioCodec.NONE)),
+        )
+    }
+
+    /** `Copy` is a codec here, not the absence of one, so a remux describes both tracks. */
+    @Test
+    fun `a remux names copy on both tracks rather than dropping them`() {
+        assertEquals(
+            "Matroska · Copy + Copy",
+            describe(OutputSpec(Container.MKV, VideoCodec.COPY, AudioCodec.COPY)),
+        )
+    }
+
+    @Test
+    fun `each engine preference has the wording the chips show`() {
+        assertEquals("Automatic", EnginePreference.AUTO.label())
+        assertEquals("Prefer hardware", EnginePreference.PREFER_HARDWARE.label())
+        assertEquals("Force software", EnginePreference.FORCE_SOFTWARE.label())
+    }
+
+    /**
+     * Two constants sharing a label would render as two identical chips, one of which the user
+     * could not choose deliberately. The exhaustive `when` cannot catch that; this does.
+     */
+    @Test
+    fun `no two engine preferences render the same chip`() {
+        val labels = EnginePreference.entries.map { it.label() }
+
+        assertEquals(EnginePreference.entries.size, labels.toSet().size)
+        assertEquals(emptyList<String>(), labels.filter { it.isBlank() })
+    }
+}

app/src/test/java/org/libremediaconverter/convert/FileCardTest.kt

@@ -0,0 +1,254 @@
+package org.libremediaconverter.convert
+
+import android.net.Uri
+import androidx.compose.ui.test.assertCountEquals
+import androidx.compose.ui.test.assertTextEquals
+import androidx.compose.ui.test.onChildren
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.media3.common.util.UnstableApi
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.libremediaconverter.createDrainedComposeRule
+import org.libremediaconverter.model.AudioCodec
+import org.libremediaconverter.model.Container
+import org.libremediaconverter.model.InputKind
+import org.libremediaconverter.model.InputProbe
+import org.libremediaconverter.model.VideoCodec
+import org.libremediaconverter.ui.TestTags
+import org.robolectric.RobolectricTestRunner
+
+/**
+ * What the source-info card says when it does not know something.
+ *
+ * The defect is a card that invents an answer instead of admitting it has none. Two of them are
+ * live here and neither had a test before this file:
+ *
+ * - **`InputFile.sizeBytes` is nullable and the card is the reader that has to say so in words.**
+ *   `sizeBytes` used to be `0L` for "nobody told me", and [UnknownInputSizeTest] records what that
+ *   cost at the space check. The card is the other reader, and its failure mode is the mirror
+ *   image: hand the null to `formatBytes` and it renders `"0 B"` -- a measurement, shown to the
+ *   user, that no provider ever made. It renders **independently of the probe**, which is why the
+ *   same assertion appears twice below, with the probe present and absent. That independence is
+ *   the contract; a test covering only the probed case would leave the branch a user actually hits
+ *   first -- the card is on screen before the probe finishes -- unguarded.
+ * - **The codec rows degrade in words too.** `CodecNames.describeVideo`/`describeAudio` answer
+ *   `"Unknown"` for a codec nothing named, the `VIDEO` branch answers `"No audio track"` for a file
+ *   with no audio, and the two `> 0` guards drop the dimension and length rows rather than printing
+ *   `0` and `0:00`. Each of those has a case below on **both** sides of the guard, because a test
+ *   of the present side alone stays green with the guard deleted.
+ *
+ * ### What cannot be asserted here, so that it is a decision rather than an omission
+ *
+ * The `probe == null` branch exits before `HorizontalDivider`, and **the divider's absence is not
+ * observable from a test**: Material 3 renders it as a `Box` with no semantics modifier, so it
+ * contributes no node to the semantics tree at all. What is asserted instead is everything the
+ * divider precedes -- no detail row for any label the four kind branches can emit -- plus the
+ * card's child count, which pins "these three texts and nothing else" without having to enumerate.
+ *
+ * The early exit itself is enforced by the compiler rather than by this file, which the PR body
+ * records: deleting `return@Column` un-smart-casts `probe`, and the `probe.kind` below it stops
+ * compiling. The mutation that reddens the test here is the compilable form of that regression --
+ * defaulting the null away with `?: InputProbe()` and letting the kind rows render.
+ */
+@UnstableApi
+@RunWith(RobolectricTestRunner::class)
+class FileCardTest {
+
+    @get:Rule
+    val composeRule = createDrainedComposeRule()
+
+    @Test
+    fun `a file no provider could measure says so in words rather than showing a zero`() {
+        setFileCard(input(sizeBytes = null, probe = VIDEO_PROBE))
+
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD_BYTES)
+            .assertTextEquals("Size unknown")
+    }
+
+    /**
+     * The same line, with no probe at all. Separate from the case above rather than folded into
+     * it because `setContent` may only be called once per rule, and because two independent reds
+     * are the evidence that the size line does not depend on the probe.
+     */
+    @Test
+    fun `the size line says the same thing while the probe is still running`() {
+        setFileCard(input(sizeBytes = null, probe = null))
+
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD_BYTES)
+            .assertTextEquals("Size unknown")
+    }
+
+    @Test
+    fun `a size that was reported is formatted rather than replaced by the unknown line`() {
+        setFileCard(input(sizeBytes = 12_345_678L, probe = VIDEO_PROBE))
+
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD_NAME).assertTextEquals("clip.mkv")
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD_BYTES).assertTextEquals("12.3 MB")
+    }
+
+    /**
+     * The note and the emptiness are one behaviour, so they are one test: a regression that keeps
+     * the note but renders the rows anyway would leave a note-only test green.
+     */
+    @Test
+    fun `while the probe is still running the card shows the reading note and nothing else`() {
+        setFileCard(input(probe = null))
+
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD_NOTE)
+            .assertTextEquals("Reading…")
+        assertNoDetailRows()
+        // Name, size, note. Catches a row whose label is not in EVERY_ROW_LABEL as well.
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD).onChildren().assertCountEquals(3)
+    }
+
+    @Test
+    fun `a file nothing could read gets the explanatory line instead of unknown codecs`() {
+        setFileCard(input(probe = InputProbe(kind = InputKind.UNPARSEABLE)))
+
+        composeRule.onNodeWithTag(TestTags.Converter.FILE_CARD_NOTE)
+            .assertTextEquals("Could not identify this file. It will be converted with FFmpeg.")
+        assertNoDetailRows()
+    }
+
+    @Test
+    fun `an image gets its type and its pixel dimensions`() {
+        setFileCard(input(probe = InputProbe(kind = InputKind.IMAGE, width = 1920, height = 1080)))
+
+        assertRow("Type", "Image")
+        assertRow("Size", "1920×1080")
+    }
+
+    /** The `width > 0` guard, from the side that would print `0×0` if it were dropped. */
+    @Test
+    fun `an image whose dimensions nothing reported gets the type row alone`() {
+        setFileCard(input(probe = InputProbe(kind = InputKind.IMAGE)))
+
+        assertRow("Type", "Image")
+        assertNoRow("Size")
+    }
+
+    @Test
+    fun `an audio-only file says it has no video track rather than leaving the row blank`() {
+        setFileCard(
+            input(
+                probe = InputProbe(
+                    audioCodec = "aac",
+                    hasVideo = false,
+                    durationMs = 90_000,
+                    kind = InputKind.AUDIO_ONLY,
+                    container = Container.MP3,
+                ),
+            ),
+        )
+
+        assertRow("Container", Container.MP3.label)
+        assertRow("Video", "No video track")
+        assertRow("Audio", AudioCodec.AAC.label)
+        assertRow("Length", "1:30")
+        assertNoRow("Type")
+        assertNoRow("Size")
+    }
+
+    /**
+     * Everything the audio branch can fail to know, at once: no container, no codec name, no
+     * duration. Each degrades in its own words, and the length row disappears rather than
+     * claiming `0:00`.
+     */
+    @Test
+    fun `an audio-only file nothing else could describe degrades one row at a time`() {
+        setFileCard(input(probe = InputProbe(hasVideo = false, kind = InputKind.AUDIO_ONLY)))
+
+        assertRow("Container", "Unknown")
+        assertRow("Video", "No video track")
+        assertRow("Audio", "Unknown")
+        assertNoRow("Length")
+    }
+
+    @Test
+    fun `a video file composes its codec with its dimensions on one row`() {
+        setFileCard(input(probe = VIDEO_PROBE))
+
+        assertRow("Container", Container.MP4.label)
+        assertRow("Video", "${VideoCodec.H264.label} · 1920×1080")
+        assertRow("Audio", AudioCodec.AAC.label)
+        assertRow("Length", "1:30")
+    }
+
+    /**
+     * `"No audio track"` rather than `describeAudio(null)`'s `"Unknown"`. The video branch knows
+     * the difference between a track it could not name and a track that is not there; the audio
+     * branch above cannot, because a file with no audio is not audio-only.
+     */
+    @Test
+    fun `a video file with no audio track says so instead of naming an unknown codec`() {
+        setFileCard(input(probe = VIDEO_PROBE.copy(audioCodec = null)))
+
+        assertRow("Audio", "No audio track")
+    }
+
+    /** Both `> 0` guards on the video branch, plus the codec name nothing supplied. */
+    @Test
+    fun `a video file missing its codec, dimensions and duration omits them rather than faking them`() {
+        setFileCard(
+            input(
+                probe = VIDEO_PROBE.copy(
+                    videoCodec = null,
+                    width = 0,
+                    height = 0,
+                    durationMs = 0,
+                ),
+            ),
+        )
+
+        assertRow("Video", "Unknown")
+        assertNoRow("Length")
+    }
+
+    /**
+     * The row is one node, not a label node beside a value node. A test matching on `"Container"`
+     * alone would pass against either shape.
+     */
+    @Test
+    fun `a detail row renders its label and its value as a single node`() {
+        composeRule.setContent { DetailRow("Container", "Matroska") }
+
+        composeRule.onNodeWithTag(TestTags.Converter.detailRow("Container"))
+            .assertTextEquals("Container: Matroska")
+    }
+
+    private fun setFileCard(input: InputFile) = composeRule.setContent { FileCard(input) }
+
+    private fun input(sizeBytes: Long? = 12_345_678L, probe: InputProbe? = VIDEO_PROBE) = InputFile(
+        uri = Uri.parse("content://test/clip.mkv"),
+        displayName = "clip.mkv",
+        sizeBytes = sizeBytes,
+        probe = probe,
+    )
+
+    private fun assertRow(label: String, value: String) {
+        composeRule.onNodeWithTag(TestTags.Converter.detailRow(label))
+            .assertTextEquals("$label: $value")
+    }
+
+    private fun assertNoRow(label: String) {
+        composeRule.onNodeWithTag(TestTags.Converter.detailRow(label)).assertDoesNotExist()
+    }
+
+    private fun assertNoDetailRows() = EVERY_ROW_LABEL.forEach(::assertNoRow)
+
+    private companion object {
+        /** Every label the four kind branches can emit, so absence can be asserted exhaustively. */
+        val EVERY_ROW_LABEL = listOf("Container", "Video", "Audio", "Length", "Type", "Size")
+
+        val VIDEO_PROBE = InputProbe(
+            videoCodec = "h264",
+            audioCodec = "aac",
+            durationMs = 90_000,
+            kind = InputKind.VIDEO,
+            container = Container.MP4,
+            width = 1920,
+            height = 1080,
+        )
+    }
+}