Update regex to match expected format

lint/src/main/kotlin/com/google/samples/apps/nowinandroid/lint/TestMethodDetector.kt

@@ -83,7 +83,7 @@ class TestMethodDetector : Detector(), SourceCodeScanner {
         usageInfo: AnnotationUsageInfo,
     ) {
         if (!context.isAndroidTest()) return
-        if ("""^[^\W_]+_[^\W_]+_[^\W_]+$""".toRegex().matches(name)) return
+        if ("""[^\W_]+(_[^\W_]+){1,2}""".toRegex().matches(name)) return
         context.report(
             issue = FORMAT,
             scope = usageInfo.usage,
@@ -153,8 +153,8 @@ class TestMethodDetector : Detector(), SourceCodeScanner {
         @JvmField
         val FORMAT: Issue = issue(
             id = "TestMethodFormat",
-            briefDescription = "Test method does not follow the `given_when_then` format",
+            briefDescription = "Test method does not follow the `given_when_then` or `when_then` format",
-            explanation = "Test method should follow the `given_when_then` format.",
+            explanation = "Test method should follow the `given_when_then` or `when_then` format.",
         )
     }
 }

lint/src/test/kotlin/com/google/samples/apps/nowinandroid/lint/TestMethodDetectorTest.kt

@@ -81,10 +81,17 @@ class TestMethodDetectorTest {
                     """
                     import org.junit.Test
                     class Test {
+                        @Test
+                        fun when_then() = Unit
                         @Test
                         fun given_when_then() = Unit
+
+                        @Test
+                        fun foo() = Unit
+                        @Test
+                        fun foo_bar_baz_qux() = Unit
                         @Test
-                        fun given_foo_when_bar_then_baz() = Unit
+                        fun `foo bar baz`() = Unit
                     }
                 """,
                 ).indented(),
@@ -92,10 +99,16 @@ class TestMethodDetectorTest {
             .run()
             .expect(
                 """
-                src/androidTest/com/example/Test.kt:6: Warning: Test method does not follow the given_when_then format [TestMethodFormat]
+                src/androidTest/com/example/Test.kt:9: Warning: Test method does not follow the given_when_then or when_then format [TestMethodFormat]
-                    fun given_foo_when_bar_then_baz() = Unit
+                    fun foo() = Unit
-                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                        ~~~
-                0 errors, 1 warnings
+                src/androidTest/com/example/Test.kt:11: Warning: Test method does not follow the given_when_then or when_then format [TestMethodFormat]
+                    fun foo_bar_baz_qux() = Unit
+                        ~~~~~~~~~~~~~~~
+                src/androidTest/com/example/Test.kt:13: Warning: Test method does not follow the given_when_then or when_then format [TestMethodFormat]
+                    fun `foo bar baz`() = Unit
+                        ~~~~~~~~~~~~~
+                0 errors, 3 warnings
                 """.trimIndent(),
             )
     }