Adds tests for API

api/src/test/java/com/github/gtache/autosubtitle/TestFile.java

@@ -0,0 +1,37 @@
+package com.github.gtache.autosubtitle;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.api.io.TempDir;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Objects;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class TestFile {
+
+    private final File file;
+
+    TestFile(@Mock final File file) {
+        this.file = Objects.requireNonNull(file);
+    }
+
+    @Test
+    void testGetInputStream(@TempDir final Path dir) throws IOException {
+        final var path = dir.resolve("path");
+        Files.writeString(path, "test");
+
+        when(file.getInputStream()).thenCallRealMethod();
+        when(file.path()).thenReturn(path);
+        try (final var in = file.getInputStream()) {
+            assertEquals("test", new String(in.readAllBytes()));
+        }
+    }
+}