added some test cases and refactored old test

app/src/androidTest/java/org/kiwix/kiwixmobile/mimetype/MimeTypeTest.kt

@@ -50,11 +50,11 @@ class MimeTypeTest : BaseActivityTest() {
     zimFile.createNewFile()
     loadFileStream.use { inputStream ->
       val outputStream: OutputStream = FileOutputStream(zimFile)
-      outputStream.use { outputStream ->
+      outputStream.use { it ->
         val buffer = ByteArray(1024)
         var length: Int
         while (inputStream.read(buffer).also { length = it } > 0) {
-          outputStream.write(buffer, 0, length)
+          it.write(buffer, 0, length)
         }
       }
     }
@@ -64,15 +64,19 @@ class MimeTypeTest : BaseActivityTest() {
       NightModeConfig(SharedPreferenceUtil(context), context)
     )
     zimFileReader.getRandomArticleUrl()?.let {
-      val mimeType = zimFileReader.readMimeType(it)
+      val mimeType = zimFileReader.readContentAndMimeType(it)
       if (mimeType.contains("^([^ ]+).*$") || mimeType.contains(";")) {
         Assert.fail(
           "Unable to get mime type from zim file. File = " +
             " $zimFile and url of article = $it"
         )
       }
+    }.also {
+      zimFileReader.dispose()
     } ?: kotlin.run {
       Assert.fail("Unable to get article from zim file $zimFile")
+    }.also {
+      zimFileReader.dispose()
     }
   }
 }

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimFileReader.kt

@@ -126,8 +126,8 @@ class ZimFileReader constructor(
     return loadContent(uri)
   }
 
-  fun readMimeType(uri: String): String = getContentAndMimeType(uri)
+  fun readContentAndMimeType(uri: String): String = getContentAndMimeType(uri)
-    .second.replace("^([^ ]+).*$", "$1").substringBefore(";").also {
+    .second.truncateMimeType.also {
       Log.d(TAG, "getting mimetype for $uri = $it")
     }
 
@@ -268,5 +268,9 @@ private val Uri.filePath: String
 private val String.filePath: String
   get() = substringAfter(CONTENT_PREFIX).substringBefore("#").substringBefore("?")
 
+// Truncate mime-type (everything after the first space and semi-colon(if exists)
+val String.truncateMimeType: String
+  get() = replace("^([^ ]+).*$", "$1").substringBefore(";")
+
 private val Pair.parcelFileDescriptor: ParcelFileDescriptor?
   get() = ParcelFileDescriptor.open(File(filename), ParcelFileDescriptor.MODE_READ_ONLY)

core/src/main/java/org/kiwix/kiwixmobile/core/reader/ZimReaderContainer.kt

@@ -48,7 +48,11 @@ class ZimReaderContainer @Inject constructor(private val zimFileReaderFactory: F
   fun getRedirect(url: String): String = zimFileReader?.getRedirect(url) ?: ""
   fun load(url: String, requestHeaders: Map<String, String>): WebResourceResponse {
     val data = zimFileReader?.load(url)
-    return WebResourceResponse(zimFileReader?.readMimeType(url), Charsets.UTF_8.name(), data)
+    return WebResourceResponse(
+      zimFileReader?.readContentAndMimeType(url),
+      Charsets.UTF_8.name(),
+      data
+    )
       .apply {
         val headers = mutableMapOf("Accept-Ranges" to "bytes")
         if ("Range" in requestHeaders.keys) {

core/src/sharedTestFunctions/java/org/kiwix/kiwixmobile/core/reader/ZimFileReaderTest.kt

@@ -0,0 +1,42 @@
+/*
+ * Kiwix Android
+ * Copyright (c) 2022 Kiwix <android.kiwix.org>
+ * 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 <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package org.kiwix.kiwixmobile.core.reader
+
+import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertEquals
+
+class ZimFileReaderTest {
+  @Test
+  fun checkMimeTypeWithSemicolon() {
+    val mimeTypeHtml = "text/html;"
+    assertEquals("text/html", mimeTypeHtml.truncateMimeType)
+  }
+
+  @Test
+  fun checkMimeTypeWithSpecialCharacters() {
+    val mimeTypeCss = "text/css^([^ ]+).*\$"
+    assertEquals("text/css$1", mimeTypeCss.truncateMimeType)
+  }
+
+  @Test
+  fun checkMimeTypeWithSemicolonBeforeSpecialCharacters() {
+    val mimeTypeCss = "text/application;^([^ ]+).*\$;"
+    assertEquals("text/application", mimeTypeCss.truncateMimeType)
+  }
+}