From cd2cb106f317f6b4e4d3a7de249f7860f3b0ac64 Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sat, 7 Aug 2021 15:47:20 -0300
Subject: [PATCH 01/14] Add initial tests

---
 tests/conftest.py        | 19 +++++++++++++++++++
 tests/test_solidmotor.py | 19 ++++++++++++++++++-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/tests/conftest.py b/tests/conftest.py
index e446d0a1..70601255 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,4 +1,5 @@
 import pytest
+from rocketpy import SolidMotor
 
 
 def pytest_addoption(parser):
@@ -11,6 +12,24 @@ def pytest_configure(config):
     config.addinivalue_line("markers", "slow: mark test as slow to run")
 
 
+@pytest.fixture
+def solid_motor():
+    example_motor = SolidMotor(
+        thrustSource="data/motors/Cesaroni_M1670.eng",
+        burnOut=3.9,
+        grainNumber=5,
+        grainSeparation=5 / 1000,
+        grainDensity=1815,
+        grainOuterRadius=33 / 1000,
+        grainInitialInnerRadius=15 / 1000,
+        grainInitialHeight=120 / 1000,
+        nozzleRadius=33 / 1000,
+        throatRadius=11 / 1000,
+        interpolationMethod="linear",
+    )
+    return example_motor
+
+
 def pytest_collection_modifyitems(config, items):
     if config.getoption("--runslow"):
         # --runslow given in cli: do not skip slow tests
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 8f545bd9..34c62baf 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -1,8 +1,9 @@
 from unittest.mock import patch
 
+import numpy as np
 import pytest
 
-from rocketpy import Environment, SolidMotor, Rocket, Flight
+from rocketpy import SolidMotor, Function
 
 
 @patch("matplotlib.pyplot.show")
@@ -22,3 +23,19 @@ def test_motor(mock_show):
     )
 
     assert example_motor.allInfo() == None
+
+@patch("matplotlib.pyplot.show")
+def test_initilize_motor_correctly(mock_plt, solid_motor):
+    grain_vol = 0.12 * (np.pi * (0.033**2 - 0.015**2))
+    grain_mass = grain_vol * 1815
+
+    assert solid_motor.maxThrust == 2200.0
+    assert solid_motor.maxThrustTime == 0.15
+    assert solid_motor.burnOutTime == 3.9
+    assert solid_motor.totalImpulse == solid_motor.thrust.integral(0, 3.9)
+    assert solid_motor.averageThrust == solid_motor.thrust.integral(0, 3.9) / 3.9
+    assert solid_motor.grainInitialVolume == grain_vol
+    assert solid_motor.grainInitialMass == grain_mass
+    assert solid_motor.propellantInitialMass == 5 * grain_mass
+    assert solid_motor.exaust_velocity == solid_motor.thrust.integral(0, 3.9) / (5 * grain_mass)
+

From 90207d69b1b077bf5e286493ac33cbac8f6d373b Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sat, 7 Aug 2021 16:34:31 -0300
Subject: [PATCH 02/14] Added SolidMotor tests #1

---
 rocketpy/SolidMotor.py   | 48 +++++++++++++++++++++++++---------------
 tests/test_solidmotor.py | 11 ++++++---
 2 files changed, 38 insertions(+), 21 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index aa22aed7..75d6a656 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -435,6 +435,10 @@ def evaluateMass(self):
         # Return Mass Function
         return self.mass
 
+    @property
+    def throatArea(self):
+        return np.pi * self.throatRadius ** 2
+
     def evaluateGeometry(self):
         """Calculates grain inner radius and grain height as a
         function of time by assuming that every propellant mass
@@ -464,10 +468,10 @@ def evaluateGeometry(self):
         # Define time mesh
         t = self.massDot.source[:, 0]
 
-        # Define system of differential equations
         density = self.grainDensity
         rO = self.grainOuterRadius
 
+        # Define system of differential equations
         def geometryDot(y, t):
             grainMassDot = self.massDot(t) / self.grainNumber
             rI, h = y
@@ -497,25 +501,37 @@ def geometryDot(y, t):
         )
 
         # Create functions describing burn rate, Kn and burn area
-        # Burn Area
+        self.evaluateBurnArea()
+        self.evaluateKn()
+        self.evaluateBurnRate()
+
+        return [self.grainInnerRadius, self.grainHeight]
+
+    def evaluateBurnArea(self):
         self.burnArea = (
-            2
-            * np.pi
-            * (
-                self.grainOuterRadius ** 2
-                - self.grainInnerRadius ** 2
-                + self.grainInnerRadius * self.grainHeight
-            )
-            * self.grainNumber
+                2
+                * np.pi
+                * (
+                        self.grainOuterRadius ** 2
+                        - self.grainInnerRadius ** 2
+                        + self.grainInnerRadius * self.grainHeight
+                )
+                * self.grainNumber
         )
         self.burnArea.setOutputs("Burn Area (m2)")
-        # Kn
-        throatArea = np.pi * (self.throatRadius) ** 2
+        return self.burnArea
+
+    def evaluateBurnRate(self):
+        self.burnRate = (-1) * self.massDot / (self.burnArea * self.grainDensity)
+        self.burnRate.setOutputs("Burn Rate (m/s)")
+        return self.burnRate
+
+    def evaluateKn(self):
         KnSource = (
             np.concatenate(
                 (
                     [self.grainInnerRadius.source[:, 1]],
-                    [self.burnArea.source[:, 1] / throatArea],
+                    [self.burnArea.source[:, 1] / self.throatArea],
                 )
             ).transpose()
         ).tolist()
@@ -526,11 +542,7 @@ def geometryDot(y, t):
             self.interpolate,
             "constant",
         )
-        # Burn Rate
-        self.burnRate = (-1) * self.massDot / (self.burnArea * self.grainDensity)
-        self.burnRate.setOutputs("Burn Rate (m/s)")
-
-        return [self.grainInnerRadius, self.grainHeight]
+        return self.Kn
 
     def evaluateInertia(self):
         """Calculates propellant inertia I, relative to directions
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 34c62baf..14bf2dfb 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -24,8 +24,8 @@ def test_motor(mock_show):
 
     assert example_motor.allInfo() == None
 
-@patch("matplotlib.pyplot.show")
-def test_initilize_motor_correctly(mock_plt, solid_motor):
+
+def test_initilize_motor_correctly(solid_motor):
     grain_vol = 0.12 * (np.pi * (0.033**2 - 0.015**2))
     grain_mass = grain_vol * 1815
 
@@ -37,5 +37,10 @@ def test_initilize_motor_correctly(mock_plt, solid_motor):
     assert solid_motor.grainInitialVolume == grain_vol
     assert solid_motor.grainInitialMass == grain_mass
     assert solid_motor.propellantInitialMass == 5 * grain_mass
-    assert solid_motor.exaust_velocity == solid_motor.thrust.integral(0, 3.9) / (5 * grain_mass)
+    assert solid_motor.exhaustVelocity == solid_motor.thrust.integral(0, 3.9) / (5 * grain_mass)
+
 
+def test_grain_geometry_progession(solid_motor):
+    assert np.allclose(solid_motor.grainInnerRadius.getSource()[-1][-1], solid_motor.grainOuterRadius)
+    assert solid_motor.grainInnerRadius.getSource()[0][-1] < solid_motor.grainInnerRadius.getSource()[-1][-1]
+    assert solid_motor.grainHeight.getSource()[0][-1] > solid_motor.grainHeight.getSource()[-1][-1]

From b0bcb629d397253f85a078be10b2d7eab9ae368b Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 01:33:48 -0300
Subject: [PATCH 03/14] Tests: Added docs for burnArea and burnRate alongside
 with unit tests

---
 rocketpy/SolidMotor.py   | 45 ++++++++++++++++++++++++++--------------
 tests/test_solidmotor.py | 25 ++++++++++++++++++++--
 2 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index 75d6a656..e3939f4b 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -228,7 +228,6 @@ def __init__(
         self.grainInitialInnerRadius = grainInitialInnerRadius
         self.grainInitialHeight = grainInitialHeight
         # Other quantities that will be computed
-        self.exhaustVelocity = None
         self.massDot = None
         self.mass = None
         self.grainInnerRadius = None
@@ -259,7 +258,6 @@ def __init__(
         self.grainInitialMass = self.grainDensity * self.grainInitialVolume
         self.propellantInitialMass = self.grainNumber * self.grainInitialMass
         # Dynamic quantities
-        self.evaluateExhaustVelocity()
         self.evaluateMassDot()
         self.evaluateMass()
         self.evaluateGeometry()
@@ -339,7 +337,8 @@ def evaluateTotalImpulse(self):
         # Return total impulse
         return self.totalImpulse
 
-    def evaluateExhaustVelocity(self):
+    @property
+    def exhaustVelocity(self):
         """Calculates and returns exhaust velocity by assuming it
         as a constant. The formula used is total impulse/propellant
         initial mass. The value is also stored in
@@ -354,15 +353,7 @@ def evaluateExhaustVelocity(self):
         self.exhaustVelocity : float
             Constant gas exhaust velocity of the motor.
         """
-        # Calculate total impulse if not yet done so
-        if self.totalImpulse is None:
-            self.evaluateTotalImpulse()
-
-        # Calculate exhaust velocity
-        self.exhaustVelocity = self.totalImpulse / self.propellantInitialMass
-
-        # Return exhaust velocity
-        return self.exhaustVelocity
+        return self.totalImpulse / self.propellantInitialMass
 
     def evaluateMassDot(self):
         """Calculates and returns the time derivative of propellant
@@ -381,10 +372,6 @@ def evaluateMassDot(self):
             Time derivative of total propellant mas as a function
             of time.
         """
-        # Calculate exhaust velocity if not done so already
-        if self.exhaustVelocity is None:
-            self.evaluateExhaustVelocity()
-
         # Create mass dot Function
         self.massDot = self.thrust / (-self.exhaustVelocity)
         self.massDot.setOutputs("Mass Dot (kg/s)")
@@ -508,6 +495,19 @@ def geometryDot(y, t):
         return [self.grainInnerRadius, self.grainHeight]
 
     def evaluateBurnArea(self):
+        """Calculates the BurnArea of the grain for
+        each time. Assuming that the grains are cylindrical
+        BATES grains.
+
+        Parameters
+        ----------
+        None
+
+        Returns
+        -------
+        burnArea : Function
+        Function representing the burn area progression with the time.
+        """
         self.burnArea = (
                 2
                 * np.pi
@@ -522,6 +522,19 @@ def evaluateBurnArea(self):
         return self.burnArea
 
     def evaluateBurnRate(self):
+        """Calculates the BurnRate with respect to time.
+        This evaluation assumes that it was already
+        calculated the massDot, burnArea timeseries.
+
+        Parameters
+        ----------
+        None
+
+        Returns
+        -------
+        burnRate : Function
+        Rate of progression of the inner radius during the combustion.
+        """
         self.burnRate = (-1) * self.massDot / (self.burnArea * self.grainDensity)
         self.burnRate.setOutputs("Burn Rate (m/s)")
         return self.burnRate
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 14bf2dfb..8fb14955 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -25,7 +25,7 @@ def test_motor(mock_show):
     assert example_motor.allInfo() == None
 
 
-def test_initilize_motor_correctly(solid_motor):
+def test_initilize_motor_asserts_dynamic_values(solid_motor):
     grain_vol = 0.12 * (np.pi * (0.033**2 - 0.015**2))
     grain_mass = grain_vol * 1815
 
@@ -40,7 +40,28 @@ def test_initilize_motor_correctly(solid_motor):
     assert solid_motor.exhaustVelocity == solid_motor.thrust.integral(0, 3.9) / (5 * grain_mass)
 
 
-def test_grain_geometry_progession(solid_motor):
+def test_grain_geometry_progession_asserts_extreme_values(solid_motor):
     assert np.allclose(solid_motor.grainInnerRadius.getSource()[-1][-1], solid_motor.grainOuterRadius)
     assert solid_motor.grainInnerRadius.getSource()[0][-1] < solid_motor.grainInnerRadius.getSource()[-1][-1]
     assert solid_motor.grainHeight.getSource()[0][-1] > solid_motor.grainHeight.getSource()[-1][-1]
+
+
+def test_mass_curve_asserts_extreme_values(solid_motor):
+    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
+    grain_mass = grain_vol * 1815
+
+    assert np.allclose(solid_motor.mass.getSource()[-1][-1], 0)
+    assert np.allclose(solid_motor.mass.getSource()[0][-1], 5 * grain_mass)
+
+
+def test_burn_area_asserts_extreme_values(solid_motor):
+    initial_burn_area = 2 * np.pi * (
+            solid_motor.grainOuterRadius**2 - solid_motor.grainInitialInnerRadius**2 +
+            solid_motor.grainInitialInnerRadius * solid_motor.grainInitialHeight
+    ) * 5
+    final_burn_area = 2 * np.pi * (
+        solid_motor.grainInnerRadius.getSource()[-1][-1] * solid_motor.grainHeight.getSource()[-1][-1]
+    ) * 5
+
+    assert np.allclose(solid_motor.burnArea.getSource()[0][-1], initial_burn_area)
+    assert np.allclose(solid_motor.burnArea.getSource()[-1][-1], final_burn_area)

From ce8ee5f02623806d3f37a47033dcd71a8d64c89a Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 10:00:10 -0300
Subject: [PATCH 04/14] Update makefile

---
 Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 5de27676..b89cf095 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,11 @@
 test:
-	pytest tests -vv
+	python -m pytest tests -vv
 
 tests: 
 	test
 
 coverage: 
-	pytest --cov=rocketpy tests -vv
+	python -m pytest --cov=rocketpy tests -vv
 
 install: 
 	python -m pip install --upgrade pip

From ccfa5bb05f547f8378e124f62975d28f59ba815b Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 10:00:33 -0300
Subject: [PATCH 05/14] Improved readbility of InertiaZDot

---
 rocketpy/SolidMotor.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index e3939f4b..eb2cf17c 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -626,8 +626,9 @@ def evaluateInertia(self):
 
         # Inertia Z Dot
         self.inertiaZDot = (
-            (1 / 2.0) * (self.massDot * self.grainOuterRadius ** 2)
-            + (1 / 2.0) * (self.massDot * self.grainInnerRadius ** 2)
+            (1 / 2.0)
+            * self.massDot
+            * (self.grainOuterRadius ** 2 + self.grainInnerRadius ** 2)
             + self.mass * self.grainInnerRadius * self.burnRate
         )
         self.inertiaZDot.setOutputs("Propellant Inertia Z Dot (kg*m2/s)")

From d3fc7dafcc77a85b0110797a2a359a5b7c8cc272 Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 10:03:34 -0300
Subject: [PATCH 06/14] Add inertiaZDot to __init__

---
 rocketpy/SolidMotor.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index eb2cf17c..847fb4b9 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -238,7 +238,7 @@ def __init__(
         self.inertiaI = None
         self.inertiaIDot = None
         self.inertiaZ = None
-        self.inertiaDot = None
+        self.inertiaZDot = None
         self.maxThrust = None
         self.maxThrustTime = None
         self.averageThrust = None
@@ -611,7 +611,7 @@ def evaluateInertia(self):
         )
 
         # Calculate inertia I dot for all grains
-        self.inertiaIDot = grainNumber * (grainInertiaIDot) + grainMassDot * np.sum(
+        self.inertiaIDot = grainNumber * grainInertiaIDot + grainMassDot * np.sum(
             d ** 2
         )
         self.inertiaIDot.setOutputs("Propellant Inertia I Dot (kg*m2/s)")

From 8989d4e4050eb7bcb507be5452919d496df3bbde Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 10:26:41 -0300
Subject: [PATCH 07/14] Add coverage html report

---
 Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Makefile b/Makefile
index b89cf095..4c66b4b8 100644
--- a/Makefile
+++ b/Makefile
@@ -7,6 +7,9 @@ tests:
 coverage: 
 	python -m pytest --cov=rocketpy tests -vv
 
+coverage-report:
+	python -m pytest --cov=rocketpy tests -vv --cov-report html
+
 install: 
 	python -m pip install --upgrade pip
 	pip install -r requirements.txt

From 23c9790211393f1c4bc119e4a3420460b5aaaef2 Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 10:28:46 -0300
Subject: [PATCH 08/14] Add tests for inertia Z and I

---
 rocketpy/SolidMotor.py   |  4 ++--
 tests/test_solidmotor.py | 35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index 847fb4b9..d0ff24b5 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -590,11 +590,11 @@ def evaluateInertia(self):
 
         # Calculate each grain's distance d to propellant center of mass
         initialValue = (grainNumber - 1) / 2
-        d = np.linspace(-initialValue, initialValue, self.grainNumber)
+        d = np.linspace(-initialValue, initialValue, grainNumber)
         d = d * (self.grainInitialHeight + self.grainSeparation)
 
         # Calculate inertia for all grains
-        self.inertiaI = grainNumber * (grainInertiaI) + grainMass * np.sum(d ** 2)
+        self.inertiaI = grainNumber * grainInertiaI + grainMass * np.sum(d ** 2)
         self.inertiaI.setOutputs("Propellant Inertia I (kg*m2)")
 
         # Inertia I Dot
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 8fb14955..682f8af8 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -3,7 +3,7 @@
 import numpy as np
 import pytest
 
-from rocketpy import SolidMotor, Function
+from rocketpy import SolidMotor
 
 
 @patch("matplotlib.pyplot.show")
@@ -65,3 +65,36 @@ def test_burn_area_asserts_extreme_values(solid_motor):
 
     assert np.allclose(solid_motor.burnArea.getSource()[0][-1], initial_burn_area)
     assert np.allclose(solid_motor.burnArea.getSource()[-1][-1], final_burn_area)
+
+
+def test_evaluate_inertia_I_asserts_extreme_values(solid_motor):
+    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
+    grain_mass = grain_vol * 1815
+
+    grainNumber = 5
+    grainInertiaI_initial = grain_mass * (
+            (1 / 4) * (0.033 ** 2 + 0.016 ** 2)
+            + (1 / 12) * 0.12 ** 2
+    )
+
+    initialValue = (grainNumber - 1) / 2
+    d = np.linspace(-initialValue, initialValue, grainNumber)
+    d = d * (0.12 + 0.005)
+
+    inertiaI_initial = grainNumber * grainInertiaI_initial + grain_mass * np.sum(d ** 2)
+
+    assert np.allclose(solid_motor.inertiaI.getSource()[0][-1], inertiaI_initial, atol=0.01)
+    assert np.allclose(solid_motor.inertiaI.getSource()[-1][-1], 0, atol=1e-16)
+
+
+def test_evaluate_inertia_Z_asserts_extreme_values(solid_motor):
+    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
+    grain_mass = grain_vol * 1815
+
+    grainInertiaZ_initial = \
+        grain_mass \
+        * (1 / 2.0) \
+        * (0.016 ** 2 + 0.033 ** 2)
+
+    assert np.allclose(solid_motor.inertiaZ.getSource()[0][-1], grainInertiaZ_initial, atol=0.01)
+    assert np.allclose(solid_motor.inertiaZ.getSource()[-1][-1], 0, atol=1e-16)

From fc6ab9efec7f8a93356b06366e3bcef0d5b1af58 Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 11:28:08 -0300
Subject: [PATCH 09/14] Add tests for reshaped thrust curve

---
 rocketpy/SolidMotor.py                        |  3 +-
 tests/fixtures/motor/Cesaroni_M1670.eng       | 18 ++++
 .../fixtures/motor/Cesaroni_M1670_shifted.eng | 16 ++++
 tests/test_solidmotor.py                      | 92 ++++++++++++++++++-
 4 files changed, 126 insertions(+), 3 deletions(-)
 create mode 100644 tests/fixtures/motor/Cesaroni_M1670.eng
 create mode 100644 tests/fixtures/motor/Cesaroni_M1670_shifted.eng

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index d0ff24b5..41279275 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -295,7 +295,6 @@ def reshapeThrustCurve(
         # Retrieve current thrust curve data points
         timeArray = self.thrust.source[:, 0]
         thrustArray = self.thrust.source[:, 1]
-
         # Move start to time = 0
         if startAtZero and timeArray[0] != 0:
             timeArray = timeArray - timeArray[0]
@@ -715,7 +714,7 @@ def exportEng(self, fileName, motorName):
         )
 
         # Write thrust curve data points
-        for item in self.thrust.source[:-1, :]:
+        for item in self.thrust.source[:-1, :][1:]:
             time = item[0]
             thrust = item[1]
             file.write("{:.4f} {:.3f}\n".format(time, thrust))
diff --git a/tests/fixtures/motor/Cesaroni_M1670.eng b/tests/fixtures/motor/Cesaroni_M1670.eng
new file mode 100644
index 00000000..3cb9e1bb
--- /dev/null
+++ b/tests/fixtures/motor/Cesaroni_M1670.eng
@@ -0,0 +1,18 @@
+M1670-BS 75 757 0 3.101 5.231 CTI 
+0.055 100
+0.092 1500
+0.1 2000
+0.15 2200
+0.2 1800
+0.5 1950
+1 2034
+;this motor is COTS
+1.5 2000
+2 1900
+2.5 1760
+2.9 1700
+3 1650
+;3.9 burnTime
+3.3 530
+3.4 350
+3.9 0
diff --git a/tests/fixtures/motor/Cesaroni_M1670_shifted.eng b/tests/fixtures/motor/Cesaroni_M1670_shifted.eng
new file mode 100644
index 00000000..f3a229f1
--- /dev/null
+++ b/tests/fixtures/motor/Cesaroni_M1670_shifted.eng
@@ -0,0 +1,16 @@
+M1670-BS 75 757 0 3.101 5.231 CTI 
+0.155 100
+0.192 1500
+0.2 2000
+0.25 2200
+0.3 1800
+0.6 1950
+1.1 2034
+1.6 2000
+2.1 1900
+2.6 1760
+3 1700
+3.1 1650
+3.4 530
+3.5 350
+4.0 0
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 682f8af8..564d159e 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -1,4 +1,5 @@
 from unittest.mock import patch
+import os
 
 import numpy as np
 import pytest
@@ -9,7 +10,7 @@
 @patch("matplotlib.pyplot.show")
 def test_motor(mock_show):
     example_motor = SolidMotor(
-        thrustSource="data/motors/Cesaroni_M1670.eng",
+        thrustSource="tests/fixtures/motor/Cesaroni_M1670.eng",
         burnOut=3.9,
         grainNumber=5,
         grainSeparation=5 / 1000,
@@ -98,3 +99,92 @@ def test_evaluate_inertia_Z_asserts_extreme_values(solid_motor):
 
     assert np.allclose(solid_motor.inertiaZ.getSource()[0][-1], grainInertiaZ_initial, atol=0.01)
     assert np.allclose(solid_motor.inertiaZ.getSource()[-1][-1], 0, atol=1e-16)
+
+
+def tests_import_eng_asserts_read_values_correctly(solid_motor):
+    comments, description, dataPoints = solid_motor.importEng("tests/fixtures/motor/Cesaroni_M1670.eng")
+
+    assert comments == [';this motor is COTS\n', ';3.9 burnTime\n']
+    assert description == ['M1670-BS', '75', '757', '0', '3.101', '5.231', 'CTI', '\n']
+    assert dataPoints == [
+        [0, 0],
+        [0.055, 100.0],
+        [0.092, 1500.0],
+        [0.1, 2000.0],
+        [0.15, 2200.0],
+        [0.2, 1800.0],
+        [0.5, 1950.0],
+        [1.0, 2034.0],
+        [1.5, 2000.0],
+        [2.0, 1900.0],
+        [2.5, 1760.0],
+        [2.9, 1700.0],
+        [3.0, 1650.0],
+        [3.3, 530.0],
+        [3.4, 350.0],
+        [3.9, 0.0]
+    ]
+
+
+def tests_export_eng_asserts_exported_values_correct(solid_motor):
+    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
+    grain_mass = grain_vol * 1815 * 5
+
+    solid_motor.exportEng(fileName='tests/solid_motor.eng', motorName='test_motor')
+    comments, description, dataPoints = solid_motor.importEng('tests/solid_motor.eng')
+    os.remove('tests/solid_motor.eng')
+
+    assert comments == []
+    assert description == [
+        'test_motor',
+        '{:3.1f}'.format(2000 * 0.033),
+        '{:3.1f}'.format(1000 * 5 * (0.12 + 0.005)),
+        '0',
+        '{:2.3}'.format(grain_mass),
+        '{:2.3}'.format(grain_mass),
+        'PJ',
+        '\n'
+    ]
+
+    assert dataPoints == [
+        [0, 0],
+        [0.055, 100.0],
+        [0.092, 1500.0],
+        [0.1, 2000.0],
+        [0.15, 2200.0],
+        [0.2, 1800.0],
+        [0.5, 1950.0],
+        [1.0, 2034.0],
+        [1.5, 2000.0],
+        [2.0, 1900.0],
+        [2.5, 1760.0],
+        [2.9, 1700.0],
+        [3.0, 1650.0],
+        [3.3, 530.0],
+        [3.4, 350.0],
+        [3.9, 0.0]
+    ]
+
+
+def test_reshape_thrust_curve_asserts_resultant_thrust_curve_correct():
+    example_motor = SolidMotor(
+        thrustSource="tests/fixtures/motor/Cesaroni_M1670_shifted.eng",
+        burnOut=3.9,
+        grainNumber=5,
+        grainSeparation=5 / 1000,
+        grainDensity=1815,
+        grainOuterRadius=33 / 1000,
+        grainInitialInnerRadius=15 / 1000,
+        grainInitialHeight=120 / 1000,
+        nozzleRadius=33 / 1000,
+        throatRadius=11 / 1000,
+        reshapeThrustCurve=(5, 3000),
+        interpolationMethod="linear",
+    )
+
+    thrust_reshaped = example_motor.thrust.getSource()
+    assert thrust_reshaped[1][0] == 0.155 * (5/4)
+    assert thrust_reshaped[-1][0] == 5
+
+    assert thrust_reshaped[1][1] == 100 * (3000/7539.1875)
+    assert thrust_reshaped[7][1] == 2034 * (3000/7539.1875)

From ae277e314f293f6dddf21d8c18dc5d06fafbe464 Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 11:29:42 -0300
Subject: [PATCH 10/14] Apply linter

---
 rocketpy/SolidMotor.py   |  25 +++++-----
 tests/test_solidmotor.py | 102 ++++++++++++++++++++++++---------------
 2 files changed, 74 insertions(+), 53 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index 41279275..f4d62268 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -508,14 +508,14 @@ def evaluateBurnArea(self):
         Function representing the burn area progression with the time.
         """
         self.burnArea = (
-                2
-                * np.pi
-                * (
-                        self.grainOuterRadius ** 2
-                        - self.grainInnerRadius ** 2
-                        + self.grainInnerRadius * self.grainHeight
-                )
-                * self.grainNumber
+            2
+            * np.pi
+            * (
+                self.grainOuterRadius ** 2
+                - self.grainInnerRadius ** 2
+                + self.grainInnerRadius * self.grainHeight
+            )
+            * self.grainNumber
         )
         self.burnArea.setOutputs("Burn Area (m2)")
         return self.burnArea
@@ -624,12 +624,9 @@ def evaluateInertia(self):
         self.inertiaZ.setOutputs("Propellant Inertia Z (kg*m2)")
 
         # Inertia Z Dot
-        self.inertiaZDot = (
-            (1 / 2.0)
-            * self.massDot
-            * (self.grainOuterRadius ** 2 + self.grainInnerRadius ** 2)
-            + self.mass * self.grainInnerRadius * self.burnRate
-        )
+        self.inertiaZDot = (1 / 2.0) * self.massDot * (
+            self.grainOuterRadius ** 2 + self.grainInnerRadius ** 2
+        ) + self.mass * self.grainInnerRadius * self.burnRate
         self.inertiaZDot.setOutputs("Propellant Inertia Z Dot (kg*m2/s)")
 
         return [self.inertiaI, self.inertiaZ]
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 564d159e..1176d6a5 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -27,7 +27,7 @@ def test_motor(mock_show):
 
 
 def test_initilize_motor_asserts_dynamic_values(solid_motor):
-    grain_vol = 0.12 * (np.pi * (0.033**2 - 0.015**2))
+    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
     grain_mass = grain_vol * 1815
 
     assert solid_motor.maxThrust == 2200.0
@@ -38,13 +38,23 @@ def test_initilize_motor_asserts_dynamic_values(solid_motor):
     assert solid_motor.grainInitialVolume == grain_vol
     assert solid_motor.grainInitialMass == grain_mass
     assert solid_motor.propellantInitialMass == 5 * grain_mass
-    assert solid_motor.exhaustVelocity == solid_motor.thrust.integral(0, 3.9) / (5 * grain_mass)
+    assert solid_motor.exhaustVelocity == solid_motor.thrust.integral(0, 3.9) / (
+        5 * grain_mass
+    )
 
 
 def test_grain_geometry_progession_asserts_extreme_values(solid_motor):
-    assert np.allclose(solid_motor.grainInnerRadius.getSource()[-1][-1], solid_motor.grainOuterRadius)
-    assert solid_motor.grainInnerRadius.getSource()[0][-1] < solid_motor.grainInnerRadius.getSource()[-1][-1]
-    assert solid_motor.grainHeight.getSource()[0][-1] > solid_motor.grainHeight.getSource()[-1][-1]
+    assert np.allclose(
+        solid_motor.grainInnerRadius.getSource()[-1][-1], solid_motor.grainOuterRadius
+    )
+    assert (
+        solid_motor.grainInnerRadius.getSource()[0][-1]
+        < solid_motor.grainInnerRadius.getSource()[-1][-1]
+    )
+    assert (
+        solid_motor.grainHeight.getSource()[0][-1]
+        > solid_motor.grainHeight.getSource()[-1][-1]
+    )
 
 
 def test_mass_curve_asserts_extreme_values(solid_motor):
@@ -56,13 +66,25 @@ def test_mass_curve_asserts_extreme_values(solid_motor):
 
 
 def test_burn_area_asserts_extreme_values(solid_motor):
-    initial_burn_area = 2 * np.pi * (
-            solid_motor.grainOuterRadius**2 - solid_motor.grainInitialInnerRadius**2 +
-            solid_motor.grainInitialInnerRadius * solid_motor.grainInitialHeight
-    ) * 5
-    final_burn_area = 2 * np.pi * (
-        solid_motor.grainInnerRadius.getSource()[-1][-1] * solid_motor.grainHeight.getSource()[-1][-1]
-    ) * 5
+    initial_burn_area = (
+        2
+        * np.pi
+        * (
+            solid_motor.grainOuterRadius ** 2
+            - solid_motor.grainInitialInnerRadius ** 2
+            + solid_motor.grainInitialInnerRadius * solid_motor.grainInitialHeight
+        )
+        * 5
+    )
+    final_burn_area = (
+        2
+        * np.pi
+        * (
+            solid_motor.grainInnerRadius.getSource()[-1][-1]
+            * solid_motor.grainHeight.getSource()[-1][-1]
+        )
+        * 5
+    )
 
     assert np.allclose(solid_motor.burnArea.getSource()[0][-1], initial_burn_area)
     assert np.allclose(solid_motor.burnArea.getSource()[-1][-1], final_burn_area)
@@ -74,8 +96,7 @@ def test_evaluate_inertia_I_asserts_extreme_values(solid_motor):
 
     grainNumber = 5
     grainInertiaI_initial = grain_mass * (
-            (1 / 4) * (0.033 ** 2 + 0.016 ** 2)
-            + (1 / 12) * 0.12 ** 2
+        (1 / 4) * (0.033 ** 2 + 0.016 ** 2) + (1 / 12) * 0.12 ** 2
     )
 
     initialValue = (grainNumber - 1) / 2
@@ -84,7 +105,9 @@ def test_evaluate_inertia_I_asserts_extreme_values(solid_motor):
 
     inertiaI_initial = grainNumber * grainInertiaI_initial + grain_mass * np.sum(d ** 2)
 
-    assert np.allclose(solid_motor.inertiaI.getSource()[0][-1], inertiaI_initial, atol=0.01)
+    assert np.allclose(
+        solid_motor.inertiaI.getSource()[0][-1], inertiaI_initial, atol=0.01
+    )
     assert np.allclose(solid_motor.inertiaI.getSource()[-1][-1], 0, atol=1e-16)
 
 
@@ -92,20 +115,21 @@ def test_evaluate_inertia_Z_asserts_extreme_values(solid_motor):
     grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
     grain_mass = grain_vol * 1815
 
-    grainInertiaZ_initial = \
-        grain_mass \
-        * (1 / 2.0) \
-        * (0.016 ** 2 + 0.033 ** 2)
+    grainInertiaZ_initial = grain_mass * (1 / 2.0) * (0.016 ** 2 + 0.033 ** 2)
 
-    assert np.allclose(solid_motor.inertiaZ.getSource()[0][-1], grainInertiaZ_initial, atol=0.01)
+    assert np.allclose(
+        solid_motor.inertiaZ.getSource()[0][-1], grainInertiaZ_initial, atol=0.01
+    )
     assert np.allclose(solid_motor.inertiaZ.getSource()[-1][-1], 0, atol=1e-16)
 
 
 def tests_import_eng_asserts_read_values_correctly(solid_motor):
-    comments, description, dataPoints = solid_motor.importEng("tests/fixtures/motor/Cesaroni_M1670.eng")
+    comments, description, dataPoints = solid_motor.importEng(
+        "tests/fixtures/motor/Cesaroni_M1670.eng"
+    )
 
-    assert comments == [';this motor is COTS\n', ';3.9 burnTime\n']
-    assert description == ['M1670-BS', '75', '757', '0', '3.101', '5.231', 'CTI', '\n']
+    assert comments == [";this motor is COTS\n", ";3.9 burnTime\n"]
+    assert description == ["M1670-BS", "75", "757", "0", "3.101", "5.231", "CTI", "\n"]
     assert dataPoints == [
         [0, 0],
         [0.055, 100.0],
@@ -122,7 +146,7 @@ def tests_import_eng_asserts_read_values_correctly(solid_motor):
         [3.0, 1650.0],
         [3.3, 530.0],
         [3.4, 350.0],
-        [3.9, 0.0]
+        [3.9, 0.0],
     ]
 
 
@@ -130,20 +154,20 @@ def tests_export_eng_asserts_exported_values_correct(solid_motor):
     grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
     grain_mass = grain_vol * 1815 * 5
 
-    solid_motor.exportEng(fileName='tests/solid_motor.eng', motorName='test_motor')
-    comments, description, dataPoints = solid_motor.importEng('tests/solid_motor.eng')
-    os.remove('tests/solid_motor.eng')
+    solid_motor.exportEng(fileName="tests/solid_motor.eng", motorName="test_motor")
+    comments, description, dataPoints = solid_motor.importEng("tests/solid_motor.eng")
+    os.remove("tests/solid_motor.eng")
 
     assert comments == []
     assert description == [
-        'test_motor',
-        '{:3.1f}'.format(2000 * 0.033),
-        '{:3.1f}'.format(1000 * 5 * (0.12 + 0.005)),
-        '0',
-        '{:2.3}'.format(grain_mass),
-        '{:2.3}'.format(grain_mass),
-        'PJ',
-        '\n'
+        "test_motor",
+        "{:3.1f}".format(2000 * 0.033),
+        "{:3.1f}".format(1000 * 5 * (0.12 + 0.005)),
+        "0",
+        "{:2.3}".format(grain_mass),
+        "{:2.3}".format(grain_mass),
+        "PJ",
+        "\n",
     ]
 
     assert dataPoints == [
@@ -162,7 +186,7 @@ def tests_export_eng_asserts_exported_values_correct(solid_motor):
         [3.0, 1650.0],
         [3.3, 530.0],
         [3.4, 350.0],
-        [3.9, 0.0]
+        [3.9, 0.0],
     ]
 
 
@@ -183,8 +207,8 @@ def test_reshape_thrust_curve_asserts_resultant_thrust_curve_correct():
     )
 
     thrust_reshaped = example_motor.thrust.getSource()
-    assert thrust_reshaped[1][0] == 0.155 * (5/4)
+    assert thrust_reshaped[1][0] == 0.155 * (5 / 4)
     assert thrust_reshaped[-1][0] == 5
 
-    assert thrust_reshaped[1][1] == 100 * (3000/7539.1875)
-    assert thrust_reshaped[7][1] == 2034 * (3000/7539.1875)
+    assert thrust_reshaped[1][1] == 100 * (3000 / 7539.1875)
+    assert thrust_reshaped[7][1] == 2034 * (3000 / 7539.1875)

From e691415de31351ebbb50aca83a6494933bb69be0 Mon Sep 17 00:00:00 2001
From: patrick <patricksampaio@usp.br>
Date: Sun, 8 Aug 2021 13:37:21 -0300
Subject: [PATCH 11/14] Improve test code

---
 tests/test_solidmotor.py | 58 +++++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 25 deletions(-)

diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 1176d6a5..a08ee4cf 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -6,6 +6,15 @@
 
 from rocketpy import SolidMotor
 
+burnOut = 3.9
+grainNumber = 5
+grainSeparation = 5 / 1000
+grainDensity = 1815
+grainOuterRadius = 33 / 1000
+grainInitialInnerRadius = 15 / 1000
+grainInitialHeight = 120 / 1000
+nozzleRadius = 33 / 1000
+throatRadius = 11 / 1000
 
 @patch("matplotlib.pyplot.show")
 def test_motor(mock_show):
@@ -27,19 +36,19 @@ def test_motor(mock_show):
 
 
 def test_initilize_motor_asserts_dynamic_values(solid_motor):
-    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
-    grain_mass = grain_vol * 1815
+    grain_vol = grainInitialHeight * (np.pi * (grainOuterRadius ** 2 - grainInitialInnerRadius ** 2))
+    grain_mass = grain_vol * grainDensity
 
     assert solid_motor.maxThrust == 2200.0
     assert solid_motor.maxThrustTime == 0.15
-    assert solid_motor.burnOutTime == 3.9
-    assert solid_motor.totalImpulse == solid_motor.thrust.integral(0, 3.9)
-    assert solid_motor.averageThrust == solid_motor.thrust.integral(0, 3.9) / 3.9
+    assert solid_motor.burnOutTime == burnOut
+    assert solid_motor.totalImpulse == solid_motor.thrust.integral(0, burnOut)
+    assert solid_motor.averageThrust == solid_motor.thrust.integral(0, burnOut) / burnOut
     assert solid_motor.grainInitialVolume == grain_vol
     assert solid_motor.grainInitialMass == grain_mass
-    assert solid_motor.propellantInitialMass == 5 * grain_mass
-    assert solid_motor.exhaustVelocity == solid_motor.thrust.integral(0, 3.9) / (
-        5 * grain_mass
+    assert solid_motor.propellantInitialMass == grainNumber * grain_mass
+    assert solid_motor.exhaustVelocity == solid_motor.thrust.integral(0, burnOut) / (
+        grainNumber * grain_mass
     )
 
 
@@ -58,11 +67,11 @@ def test_grain_geometry_progession_asserts_extreme_values(solid_motor):
 
 
 def test_mass_curve_asserts_extreme_values(solid_motor):
-    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
-    grain_mass = grain_vol * 1815
+    grain_vol = grainInitialHeight * (np.pi * (grainOuterRadius ** 2 - grainInitialInnerRadius ** 2))
+    grain_mass = grain_vol * grainDensity
 
     assert np.allclose(solid_motor.mass.getSource()[-1][-1], 0)
-    assert np.allclose(solid_motor.mass.getSource()[0][-1], 5 * grain_mass)
+    assert np.allclose(solid_motor.mass.getSource()[0][-1], grainNumber * grain_mass)
 
 
 def test_burn_area_asserts_extreme_values(solid_motor):
@@ -70,11 +79,11 @@ def test_burn_area_asserts_extreme_values(solid_motor):
         2
         * np.pi
         * (
-            solid_motor.grainOuterRadius ** 2
-            - solid_motor.grainInitialInnerRadius ** 2
-            + solid_motor.grainInitialInnerRadius * solid_motor.grainInitialHeight
+            grainOuterRadius ** 2
+            - grainInitialInnerRadius ** 2
+            + grainInitialInnerRadius * grainInitialHeight
         )
-        * 5
+        * grainNumber
     )
     final_burn_area = (
         2
@@ -83,7 +92,7 @@ def test_burn_area_asserts_extreme_values(solid_motor):
             solid_motor.grainInnerRadius.getSource()[-1][-1]
             * solid_motor.grainHeight.getSource()[-1][-1]
         )
-        * 5
+        * grainNumber
     )
 
     assert np.allclose(solid_motor.burnArea.getSource()[0][-1], initial_burn_area)
@@ -91,17 +100,16 @@ def test_burn_area_asserts_extreme_values(solid_motor):
 
 
 def test_evaluate_inertia_I_asserts_extreme_values(solid_motor):
-    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
-    grain_mass = grain_vol * 1815
+    grain_vol = grainInitialHeight * (np.pi * (grainOuterRadius ** 2 - grainInitialInnerRadius ** 2))
+    grain_mass = grain_vol * grainDensity
 
-    grainNumber = 5
     grainInertiaI_initial = grain_mass * (
-        (1 / 4) * (0.033 ** 2 + 0.016 ** 2) + (1 / 12) * 0.12 ** 2
+        (1 / 4) * (grainOuterRadius ** 2 + grainInitialInnerRadius ** 2) + (1 / 12) * grainInitialHeight ** 2
     )
 
     initialValue = (grainNumber - 1) / 2
     d = np.linspace(-initialValue, initialValue, grainNumber)
-    d = d * (0.12 + 0.005)
+    d = d * (grainInitialHeight + grainSeparation)
 
     inertiaI_initial = grainNumber * grainInertiaI_initial + grain_mass * np.sum(d ** 2)
 
@@ -112,10 +120,10 @@ def test_evaluate_inertia_I_asserts_extreme_values(solid_motor):
 
 
 def test_evaluate_inertia_Z_asserts_extreme_values(solid_motor):
-    grain_vol = 0.12 * (np.pi * (0.033 ** 2 - 0.015 ** 2))
-    grain_mass = grain_vol * 1815
+    grain_vol = grainInitialHeight * (np.pi * (grainOuterRadius ** 2 - grainInitialInnerRadius ** 2))
+    grain_mass = grain_vol * grainDensity
 
-    grainInertiaZ_initial = grain_mass * (1 / 2.0) * (0.016 ** 2 + 0.033 ** 2)
+    grainInertiaZ_initial = grain_mass * (1 / 2.0) * (grainInitialInnerRadius ** 2 + grainOuterRadius ** 2)
 
     assert np.allclose(
         solid_motor.inertiaZ.getSource()[0][-1], grainInertiaZ_initial, atol=0.01
@@ -161,7 +169,7 @@ def tests_export_eng_asserts_exported_values_correct(solid_motor):
     assert comments == []
     assert description == [
         "test_motor",
-        "{:3.1f}".format(2000 * 0.033),
+        "{:3.1f}".format(2000 * grainOuterRadius),
         "{:3.1f}".format(1000 * 5 * (0.12 + 0.005)),
         "0",
         "{:2.3}".format(grain_mass),

From 945210d5620d0d833516be98dc45779e625aaf50 Mon Sep 17 00:00:00 2001
From: giovaniceotto <ghceotto@gmail.com>
Date: Sun, 12 Sep 2021 13:06:12 -0300
Subject: [PATCH 12/14] MAINT: minor code refactoring in eng file export

---
 rocketpy/SolidMotor.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index f4d62268..004e3f7d 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -700,7 +700,7 @@ def exportEng(self, fileName, motorName):
         # Write first line
         file.write(
             motorName
-            + " {:3.1f} {:3.1f} 0 {:2.3} {:2.3} PJ \n".format(
+            + " {:3.1f} {:3.1f} 0 {:2.3} {:2.3} RocketPy \n".format(
                 2000 * self.grainOuterRadius,
                 1000
                 * self.grainNumber
@@ -711,9 +711,8 @@ def exportEng(self, fileName, motorName):
         )
 
         # Write thrust curve data points
-        for item in self.thrust.source[:-1, :][1:]:
-            time = item[0]
-            thrust = item[1]
+        for time, thrust in self.thrust.source[1:, :]:
+            # time, thrust = item
             file.write("{:.4f} {:.3f}\n".format(time, thrust))
 
         # Write last line

From 2dd6c39ca81a76a3d549812d42841d4c5a1a0dd7 Mon Sep 17 00:00:00 2001
From: giovaniceotto <ghceotto@gmail.com>
Date: Sun, 12 Sep 2021 13:12:58 -0300
Subject: [PATCH 13/14] MAINT: changed eng export manufacturer name to RocketPy

---
 rocketpy/SolidMotor.py   | 2 +-
 tests/test_solidmotor.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index 004e3f7d..c441bbe0 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -700,7 +700,7 @@ def exportEng(self, fileName, motorName):
         # Write first line
         file.write(
             motorName
-            + " {:3.1f} {:3.1f} 0 {:2.3} {:2.3} RocketPy \n".format(
+            + " {:3.1f} {:3.1f} 0 {:2.3} {:2.3} RocketPy\n".format(
                 2000 * self.grainOuterRadius,
                 1000
                 * self.grainNumber
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index a08ee4cf..9b9899d2 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -174,7 +174,7 @@ def tests_export_eng_asserts_exported_values_correct(solid_motor):
         "0",
         "{:2.3}".format(grain_mass),
         "{:2.3}".format(grain_mass),
-        "PJ",
+        "RocketPy",
         "\n",
     ]
 

From 8820fb4cece6e2f0e56682af184bbda3153c0ca1 Mon Sep 17 00:00:00 2001
From: giovaniceotto <ghceotto@gmail.com>
Date: Sun, 12 Sep 2021 13:28:07 -0300
Subject: [PATCH 14/14] BUG: fixed handling of whitespace in .eng description

---
 rocketpy/SolidMotor.py   | 4 ++--
 tests/test_solidmotor.py | 5 ++---
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/rocketpy/SolidMotor.py b/rocketpy/SolidMotor.py
index c441bbe0..ccb5961e 100644
--- a/rocketpy/SolidMotor.py
+++ b/rocketpy/SolidMotor.py
@@ -668,7 +668,7 @@ def importEng(self, fileName):
                 else:
                     if description == []:
                         # Extract description
-                        description = line.split(" ")
+                        description = line.strip().split(" ")
                     else:
                         # Extract thrust curve data points
                         time, thrust = re.findall(r"[-+]?\d*\.\d+|[-+]?\d+", line)
@@ -711,7 +711,7 @@ def exportEng(self, fileName, motorName):
         )
 
         # Write thrust curve data points
-        for time, thrust in self.thrust.source[1:, :]:
+        for time, thrust in self.thrust.source[1:-1, :]:
             # time, thrust = item
             file.write("{:.4f} {:.3f}\n".format(time, thrust))
 
diff --git a/tests/test_solidmotor.py b/tests/test_solidmotor.py
index 9b9899d2..f7ba6875 100644
--- a/tests/test_solidmotor.py
+++ b/tests/test_solidmotor.py
@@ -137,7 +137,7 @@ def tests_import_eng_asserts_read_values_correctly(solid_motor):
     )
 
     assert comments == [";this motor is COTS\n", ";3.9 burnTime\n"]
-    assert description == ["M1670-BS", "75", "757", "0", "3.101", "5.231", "CTI", "\n"]
+    assert description == ["M1670-BS", "75", "757", "0", "3.101", "5.231", "CTI"]
     assert dataPoints == [
         [0, 0],
         [0.055, 100.0],
@@ -174,8 +174,7 @@ def tests_export_eng_asserts_exported_values_correct(solid_motor):
         "0",
         "{:2.3}".format(grain_mass),
         "{:2.3}".format(grain_mass),
-        "RocketPy",
-        "\n",
+        "RocketPy"
     ]
 
     assert dataPoints == [