ENH: tests: _appearance_stream

Add tests for the TextStreamAppearance.

Author: PJBrs

tests/test_appearance_stream.py

@@ -0,0 +1,62 @@
+"""Test the pypdf.generic._appearance_stream module."""
+
+from pypdf.generic._appearance_stream import TextStreamAppearance
+
+
+def test_scale_text():
+    rect = (0, 0, 9.1, 55.4)
+    font_size = 10.1
+    text = "Hello World"
+    multiline = False
+    appearance_stream = TextStreamAppearance(
+        text, rect=rect, font_size=font_size, multiline=multiline
+    )
+    assert (str(font_size) + r" Tf").encode() in appearance_stream.get_data()
+    text = "This is a very very long sentence that probably will scale below the minimum font size"
+    font_size = 0.0
+    appearance_stream = TextStreamAppearance(
+        text, rect=rect, font_size=font_size, multiline=multiline
+    )
+    assert (b"4.0 Tf") in appearance_stream.get_data()
+    rect = (0, 0, 160, 360)
+    font_size = 0.0
+    text = """Welcome to pypdf
+pypdf is a free and open source pure-python PDF library capable of splitting, merging, cropping, and
+transforming the pages of PDF files. It can also add custom data, viewing options, and passwords to PDF
+files. pypdf can retrieve text and metadata from PDFs as well.
+
+See pdfly for a CLI application that uses pypdf to interact with PDFs.
+    """
+    multiline = True
+    appearance_stream = TextStreamAppearance(
+        text, rect=rect, font_size=font_size, multiline=multiline
+    )
+    assert (b"12 Tf") in appearance_stream.get_data()
+    assert b"pypdf is a free and open" in appearance_stream.get_data()
+    rect = (0, 0, 160, 160)
+    appearance_stream = TextStreamAppearance(
+        text, rect=rect, font_size=font_size, multiline=multiline
+    )
+    assert (b"8.8 Tf") in appearance_stream.get_data()
+    rect = (0, 0, 160, 12)
+    appearance_stream = TextStreamAppearance(
+        text, rect=rect, font_size=font_size, multiline=multiline
+    )
+    text = """Option A
+Option B
+Option C
+Option D
+"""
+    selection = "Option A"
+    assert (b"4.0 Tf") in appearance_stream.get_data()
+    text = "pneumonoultramicroscopicsilicovolcanoconiosis"
+    appearance_stream = TextStreamAppearance(
+        text, selection, rect=rect, font_size=font_size, multiline=multiline
+    )
+    assert (b"7.2 Tf") in appearance_stream.get_data()
+    rect = (0, 0, 10, 100)
+    text = "OneWord"
+    appearance_stream = TextStreamAppearance(
+        text, rect=rect, font_size=font_size, multiline=multiline
+    )
+    assert (b"OneWord") in appearance_stream.get_data()