diff --git a/assembler/test/conftest.py b/assembler/test/conftest.py
new file mode 100644
index 0000000..9825dfd
--- /dev/null
+++ b/assembler/test/conftest.py
@@ -0,0 +1,101 @@
+import pytest
+
+@pytest.fixture
+def basic_machine_definition():
+	return (
+			{
+				"registers": 20
+				, "memory": 100
+				, "program_memory": 500
+			}
+			, [
+				{
+					"mnemonic": "ldi"
+					, "args": ["register", "direct_input"]
+				}
+				, {
+					"mnemonic": "ld"
+					, "args": ["register", "register"]
+				}
+				, {
+					"mnemonic": "st"
+					, "args": ["register", "register"]
+				}
+				, {
+					"mnemonic": "inc"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "dec"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "add"
+					, "args": ["register", "register"]
+				}
+				, {
+					"mnemonic": "sub"
+					, "args": ["register", "register"]
+				}
+				, {
+					"mnemonic": "mul"
+					, "args": ["register", "register"]
+				}
+				, {
+					"mnemonic": "div"
+					, "args": ["register", "register"]
+				}
+				, {
+					"mnemonic": "gt"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "ge"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "lt"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "le"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "eq"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "not"
+					, "args": []
+				}
+				, {
+					"mnemonic": "jmp"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "call"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "ret"
+					, "args": []
+				}
+				, {
+					"mnemonic": "stop"
+					, "args": []
+				}
+				, {
+					"mnemonic": "cl"
+					, "args": []
+				}
+				, {
+					"mnemonic": "cjmp"
+					, "args": ["register"]
+				}
+				, {
+					"mnemonic": "ccall"
+					, "args": ["register"]
+				}
+			]
+		)
diff --git a/assembler/test/test_010_filecontext.py b/assembler/test/test_010_filecontext.py
new file mode 100644
index 0000000..e8340a4
--- /dev/null
+++ b/assembler/test/test_010_filecontext.py
@@ -0,0 +1,24 @@
+from io import StringIO
+from assembler.context import FileContext
+
+
+def test_getc_ungetc():
+	data = StringIO("abc\ndefg")
+	context = FileContext(data)
+
+	assert context.getc() == "a"
+	assert context.getc() == "b"
+	assert context._line == 0
+	assert context._column == 2
+	assert context.getc() == "c"
+	assert context.getc() == "\n"
+	assert context.getc() == "d"
+	assert context._line == 1
+	assert context._column == 1
+
+	context.ungetc("d")
+	context.ungetc("\n")
+
+	assert context._column == 3
+	assert context._line == 0
+	assert context.getc() == "\n"
diff --git a/assembler/test/test_011_tokenize.py b/assembler/test/test_011_tokenize.py
new file mode 100644
index 0000000..2a2955c
--- /dev/null
+++ b/assembler/test/test_011_tokenize.py
@@ -0,0 +1,54 @@
+from io import StringIO
+from assembler.tokenize import Tokenizer
+from assembler.context import FileContext
+
+def test_tokenize_1():
+	data = '''
+	ldi r0, 0xfefe
+	ldi r1, 0xefef
+	add r0, r1
+	'''
+	data = StringIO(data)
+	tokenizer = Tokenizer(FileContext(data))
+
+	result = list(tokenizer)
+
+	assert result == [
+		"ldi", " ", "r0", ",", "0xfefe", "\n"
+		, "ldi", " ", "r1", ",", "0xefef", "\n"
+		, "add", " ", "r0", ",", "r1", "\n"
+		]
+
+def test_tokenize_2():
+	data = '''
+	; This is a comment
+
+	ldi r0, 0xfefe
+	'''
+	data = StringIO(data)
+	tokenizer = Tokenizer(FileContext(data))
+
+	result = list(tokenizer)
+
+	assert result == [
+		";", "This", " ", "is", " ", "a", " ", "comment", "\n"
+		, "ldi", " ", "r0", ",", "0xfefe", "\n"
+		]
+
+
+def test_tokenize_3():
+	data = '''
+	ldi r0, 0xfefe
+	string:
+	.set ['h', 'e', 'l', 'l', 'o']
+	'''
+	data = StringIO(data)
+	tokenizer = Tokenizer(FileContext(data))
+
+	result = list(tokenizer)
+
+	assert result == [
+		"ldi", " ", "r0", ",", "0xfefe", "\n"
+		, "string", ":", "\n"
+		, ".", "set", " ", "[", "'h'", ",", "'e'", ",", "'l'", ",", "'l'", ",", "'o'", "]", "\n"
+		]
diff --git a/assembler/test/test_012_opcodes.py b/assembler/test/test_012_opcodes.py
new file mode 100644
index 0000000..2b7ba68
--- /dev/null
+++ b/assembler/test/test_012_opcodes.py
@@ -0,0 +1,14 @@
+from assembler.opcodes import make_opcodes
+
+
+def test_make_opcodes():
+	mnemonics = ["ldi", "ld", "st", "add", "mul"]
+
+	opcodes = make_opcodes(mnemonics)
+
+	assert opcodes == {"ldi": 32704
+			, "ld" : 16320
+			, "st": 49088
+			, "add": 8128
+			, "mul": 24512
+		}
diff --git a/assembler/test/test_013_util.py b/assembler/test/test_013_util.py
new file mode 100644
index 0000000..32a5c5f
--- /dev/null
+++ b/assembler/test/test_013_util.py
@@ -0,0 +1,35 @@
+from assembler.util import can_be_mark, can_convert_to_int, autoint
+
+
+def test_can_be_mark():
+	assert can_be_mark("this_is_a_mark") == True
+	assert can_be_mark("this_is_a_mark0") == True
+	assert can_be_mark("tHIS0") == True
+
+	assert can_be_mark("This_is_not_a_mark") == False
+	assert can_be_mark("0this_is_no_mark") == False
+	assert can_be_mark("this#is_no_mark") == False
+
+def test_can_convert_to_int():
+	assert can_convert_to_int("0xfe") == True
+	assert can_convert_to_int("0xFE") == True
+	assert can_convert_to_int("10") == True
+	assert can_convert_to_int("0b100") == True
+	assert can_convert_to_int("'a'") == True
+	assert can_convert_to_int("'\\n'") == True
+
+
+	assert can_convert_to_int("0xfg") == False
+	assert can_convert_to_int("0xFG") == False
+	assert can_convert_to_int("10a") == False
+	assert can_convert_to_int("0b20") == False
+	assert can_convert_to_int("'aa'") == False
+	assert can_convert_to_int("'\\z'") == False
+
+def test_autoint():
+	assert autoint("0xfe") == 0xfe
+	assert autoint("0xFE") == 0xfe
+	assert autoint("10") == 10
+	assert autoint("0b1010101") == 0b1010101
+	assert autoint("'a'") == ord("a")
+	assert autoint("'\\n'") == ord("\n")
diff --git a/assembler/test/test_020_basic_parsing.py b/assembler/test/test_020_basic_parsing.py
new file mode 100644
index 0000000..9e89eb9
--- /dev/null
+++ b/assembler/test/test_020_basic_parsing.py
@@ -0,0 +1,22 @@
+from io import StringIO
+import pytest
+
+from assembler.assembler import Assembler
+
+
+def test_commands(basic_machine_definition):
+	memory_definition, command_defintion = basic_machine_definition
+
+	data = StringIO(
+		'''
+		ldi r0, 0xfe
+		ldi r1, 0xfe
+		add r0, r1
+		'''
+		)
+	assembler = Assembler(data, memory_definition, command_defintion, {})
+	assembler.parse()
+
+	assert assembler._code_objects == [32704, 0, 0xfe
+					, 32704, 1, 0xfe
+					, 40896, 0, 1]