diff --git a/app/src/test/java/org/fairscan/app/data/ImageRepositoryTest.kt b/app/src/test/java/org/fairscan/app/data/ImageRepositoryTest.kt
index 61da0ee..4deab91 100644
--- a/app/src/test/java/org/fairscan/app/data/ImageRepositoryTest.kt
+++ b/app/src/test/java/org/fairscan/app/data/ImageRepositoryTest.kt
@@ -111,6 +111,13 @@ class ImageRepositoryTest {
         assertThat(repo().imageIds()).containsExactly("1")
     }
 
+    @Test
+    fun `should find existing files at initialization if json is invalid`() {
+        writeDocumentDotJson("xxx")
+        File(scanDir(), "1.jpg").writeBytes(byteArrayOf(101, 102, 103))
+        assertThat(repo().imageIds()).containsExactly("1")
+    }
+
     @Test
     fun `no json and two files with same id`() {
         scanDir().mkdirs()
@@ -132,9 +139,7 @@ class ImageRepositoryTest {
 
     @Test
     fun `should filter pages in json at initialization`() {
-        scanDir().mkdirs()
-        val json = """{"pages":[{"file":"1.jpg"}, {"file":"2.jpg"}]}"""
-        File(scanDir(), "document.json").writeText(json)
+        writeDocumentDotJson("""{"pages":[{"file":"1.jpg"}, {"file":"2.jpg"}]}""")
         File(scanDir(), "2.jpg").writeBytes(byteArrayOf(101, 102, 103))
         assertThat(repo().imageIds()).containsExactly("2")
     }
@@ -192,6 +197,13 @@ class ImageRepositoryTest {
         assertThat(repo.pages().last().metadata).isEqualTo(metadata1.copy(manualRotation = R270))
     }
 
+    @Test
+    fun rotate_unknown_id() {
+        val repo = repo()
+        repo.rotate("x", true)
+        assertThat(repo.imageIds()).isEmpty()
+    }
+
     @Test
     fun movePage() {
         val repo = repo()
@@ -207,6 +219,13 @@ class ImageRepositoryTest {
         assertThat(repo2.imageIds()).containsExactly(id1, id0)
     }
 
+    @Test
+    fun move_unknown_id() {
+        val repo = repo()
+        repo.movePage("x", 0)
+        assertThat(repo.imageIds()).isEmpty()
+    }
+
     @Test
     fun metadata() {
         val quad = quad1.toSerializable()
@@ -229,6 +248,11 @@ class ImageRepositoryTest {
     private fun jpegFiles(dir: File): Array<out File?>?
         = dir.listFiles { f -> f.name.endsWith(".jpg") }
 
+    private fun writeDocumentDotJson(json: String) {
+        scanDir().mkdirs()
+        File(scanDir(), "document.json").writeText(json)
+    }
+
     fun ImageRepository.imageIds(): PersistentList<String> =
         pages().map { it.id }.toPersistentList()
 }
diff --git a/app/src/test/java/org/fairscan/app/data/PageStoreTest.kt b/app/src/test/java/org/fairscan/app/data/PageStoreTest.kt
new file mode 100644
index 0000000..61072d9
--- /dev/null
+++ b/app/src/test/java/org/fairscan/app/data/PageStoreTest.kt
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2025 Pierre-Yves Nicolas
+ *
+ * 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.
+ * This program 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
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.fairscan.app.data
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+
+class PageStoreTest {
+
+    val page1 = PageV2("1")
+    val page2 = PageV2("2")
+
+    @Test
+    fun pages() {
+        val store = PageStore(listOf())
+        assertThat(store.pages()).isEmpty()
+
+        store.addOrReplace(page1)
+        assertThat(store.pages()).containsExactly(page1)
+
+        store.addOrReplace(page2)
+        assertThat(store.pages()).containsExactly(page1, page2)
+    }
+
+    @Test
+    fun get() {
+        val store = PageStore(listOf(page1))
+        assertThat(store.get(page1.id)).isEqualTo(page1)
+        assertThat(store.get("x")).isNull()
+    }
+
+    @Test
+    fun addOrReplace() {
+        val store = PageStore(listOf())
+        store.addOrReplace(page1)
+        assertThat(store.pages()).containsExactly(page1)
+
+        val page1b = PageV2("1", 90)
+        store.addOrReplace(page1b)
+        assertThat(store.pages()).containsExactly(page1b)
+        assertThat(page1b).isNotEqualTo(page1)
+    }
+
+    @Test
+    fun update() {
+        val page = PageV2("3", baseRotationDegrees = 90)
+        val store = PageStore(listOf(page))
+        store.update(page.id) { p -> p.copy(baseRotationDegrees = p.baseRotationDegrees + 180) }
+        assertThat(store.get(page.id)!!.baseRotationDegrees).isEqualTo(270)
+    }
+
+    @Test
+    fun delete() {
+        val store = PageStore(listOf(page1, page2))
+        assertThat(store.pages()).containsExactly(page1, page2)
+        store.delete(page1.id)
+        assertThat(store.pages()).containsExactly(page2)
+    }
+
+    @Test
+    fun clear() {
+        val store = PageStore(listOf(page1, page2))
+        store.clear()
+        assertThat(store.pages()).isEmpty()
+    }
+
+    @Test
+    fun move() {
+        val store = PageStore(listOf(page1, page2))
+        assertThat(store.pages()).containsExactly(page1, page2)
+        store.move(page2.id, 0)
+        assertThat(store.pages()).containsExactly(page2, page1)
+        store.move(page2.id, 1)
+        assertThat(store.pages()).containsExactly(page1, page2)
+        store.move("x", 0)
+        assertThat(store.pages()).containsExactly(page1, page2)
+    }
+
+}