diff --git a/app/src/test/java/agzam/vyatsu/data/remote/GroupsParserTest.kt b/app/src/test/java/agzam/vyatsu/data/remote/GroupsParserTest.kt
new file mode 100644
index 0000000..05d9f77
--- /dev/null
+++ b/app/src/test/java/agzam/vyatsu/data/remote/GroupsParserTest.kt
@@ -0,0 +1,162 @@
+package agzam.vyatsu.data.remote
+
+import agzam.vyatsu.domain.model.DateRange
+import agzam.vyatsu.domain.model.Season
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import java.io.InputStream
+
+class GroupsParserTest {
+
+    private val faculty = "Факультет автоматики и вычислительной техники (ОРУ)"
+    private val facultyShort = "ФАВТ (Факультет автоматики и вычислительной техники)"
+
+    private fun page(vararg blocks: String): String = blocks.joinToString("\n")
+
+    private fun facultyDiv(name: String): String = """<div class="fak_name">$name</div>"""
+
+    private fun groupDiv(periodId: String, name: String): String =
+        """<div class="grpPeriod" data-grp_period_id="$periodId">$name</div>"""
+
+    private fun pdfLink(url: String): String = """<a href="$url">x</a>"""
+
+    private fun parse(html: String): ParsedGroups =
+        GroupsParser.parseStream(html.byteInputStream(Charsets.UTF_8))
+
+    private fun parseLineByLine(html: String): ParsedGroups {
+        val lines = html.split("\n").map { "$it\n" }
+        var index = 0
+        val stream = object : InputStream() {
+            override fun read(): Int = -1
+            override fun read(b: ByteArray, off: Int, len: Int): Int {
+                if (index >= lines.size) return -1
+                val bytes = lines[index].toByteArray(Charsets.UTF_8)
+                val n = minOf(len, bytes.size)
+                System.arraycopy(bytes, 0, b, off, n)
+                index++
+                return n
+            }
+        }
+        return GroupsParser.parseStream(stream)
+    }
+
+    @Test
+    fun dropsLastDigitFromPeriodId() {
+        val html = page(
+            facultyDiv(faculty),
+            groupDiv("123456", "ИВТб-3304-05-00 (бакалавриат)")
+        )
+
+        val group = parse(html).groups.single()
+
+        assertEquals("12345", group.id)
+        assertEquals("ИВТб-3304-05-00", group.name)
+        assertEquals(facultyShort, group.faculty)
+    }
+
+    @Test
+    fun removesParenthesizedSuffixFromGroupName() {
+        val html = page(facultyDiv(faculty), groupDiv("777", "Группа А (подгруппа)"))
+
+        val group = parse(html).groups.single()
+
+        assertEquals("77", group.id)
+        assertEquals("Группа А", group.name)
+    }
+
+    @Test
+    fun keepsFacultyNameWhenNoShorthand() {
+        val html = page(facultyDiv("Некий институт (ОРУ)"), groupDiv("5555", "Гр"))
+
+        val group = parse(html).groups.single()
+
+        assertEquals("Некий институт", group.faculty)
+    }
+
+    @Test
+    fun facultyAppliesToGroupsUntilChanged() {
+        val html = page(
+            facultyDiv(faculty),
+            groupDiv("1111", "А-1"),
+            groupDiv("2222", "А-2"),
+            facultyDiv("Юридический институт (факультет) (ОРУ)"),
+            groupDiv("3333", "Ю-1")
+        )
+
+        val faculties = parse(html).groups.map { it.faculty }
+
+        assertEquals(
+            listOf(facultyShort, facultyShort, "ЮИ (Юридический институт)"),
+            faculties
+        )
+    }
+
+    @Test
+    fun parsesDateRangesGroupedBySeason() {
+        val html = page(
+            pdfLink("/reports/schedule/Group/12345_1_14092026_27092026.pdf"),
+            pdfLink("/reports/schedule/Group/12345_1_28092026_11102026.pdf"),
+            pdfLink("/reports/schedule/Group/12345_2_09022027_22022027.pdf")
+        )
+
+        val ranges = parse(html).dateRanges
+
+        assertEquals(
+            listOf(DateRange("14092026", "27092026"), DateRange("28092026", "11102026")),
+            ranges["12345"]?.get(Season.AUTUMN)
+        )
+        assertEquals(
+            listOf(DateRange("09022027", "22022027")),
+            ranges["12345"]?.get(Season.SPRING)
+        )
+    }
+
+    @Test
+    fun ignoresUnrelatedLinks() {
+        val html = page(
+            pdfLink("/other/12345_1_14092026_27092026.pdf"),
+            pdfLink("/reports/schedule/Group/123_1_14092026_27092026.pdf")
+        )
+
+        assertTrue(parse(html).dateRanges.isEmpty())
+    }
+
+    @Test
+    fun extractsRangesFromTextBeforeTag() {
+        val html = "/reports/schedule/Group/12345_1_14092026_27092026.pdf " + pdfLink("#")
+
+        val ranges = parse(html).dateRanges
+
+        assertEquals(
+            listOf(DateRange("14092026", "27092026")),
+            ranges["12345"]?.get(Season.AUTUMN)
+        )
+    }
+
+    @Test
+    fun greaterThanInsideQuotedAttributeDoesNotBreakTag() {
+        val html = page(
+            facultyDiv(faculty),
+            """<div class="grpPeriod" data-grp_period_id="555" title="a>b">Группа Б</div>"""
+        )
+
+        val group = parse(html).groups.single()
+
+        assertEquals("55", group.id)
+        assertEquals("Группа Б", group.name)
+    }
+
+    @Test
+    fun multipleReadsProduceSameResultAsSingleRead() {
+        val html = page(
+            facultyDiv(faculty),
+            groupDiv("123456", "ИВТб-3304-05-00 (бакалавриат)"),
+            pdfLink("/reports/schedule/Group/12345_1_14092026_27092026.pdf"),
+            groupDiv("7654321", "ИВТб-3304-05-01"),
+            pdfLink("/reports/schedule/Group/765432_2_09022027_22022027.pdf")
+        )
+
+        assertEquals(parse(html), parseLineByLine(html))
+    }
+}